v2.4.0.6

Benefit Plans | 12 Months Ended
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Dec. 31, 2012
Benefit Plans | BENEFIT PLANS (a) Pension and Other Postretirement Benefits Plans - Alliant Energy, IPL and WPL provide retirement benefits to substantially all of their employees through various qualified and non-qualified non-contributory defined benefit pension plans, and/or through defined contribution plans (including 401(k) savings plans). Alliant Energy’s, IPL’s and WPL’s qualified and non-qualified non-contributory defined benefit pension plans are currently closed to new hires. Benefits of the non-contributory defined benefit pension plans are based on the plan participant’s years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant’s years of service, age, compensation and contributions. Alliant Energy, IPL and WPL also provide certain defined benefit postretirement health care and life benefits to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory. Assumptions - The assumptions for defined benefit pension and other postretirement benefits plans at the measurement date of December 31 were as follows (Not Applicable (N/A)):
Alliant Energy | Defined Benefit Pension Plans |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.11% |  | 4.86% |  | 5.56% |  | 3.82% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.86% |  | 5.56% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.50% |  | 7.00% |  | 6.90%
Rate of compensation increase | 3.50 | % | - | 4.50% |  | 3.50 | % | - | 4.50% |  | 3.50 | % | - | 4.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
IPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.20% |  | 4.95% |  | 5.70% |  | 3.76% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.95% |  | 5.70% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.40% |  | 7.30% |  | 7.10%
Rate of compensation increase | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
WPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.20% |  | 4.95% |  | 5.70% |  | 3.81% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.95% |  | 5.70% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.00% |  | 6.30% |  | 6.30%
Rate of compensation increase | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
Expected rate of return on plan assets - The expected rate of return on plan assets is determined by analysis of projected asset class returns based on the target asset class allocations. Alliant Energy, IPL and WPL use a forward-looking building blocks approach and also review historical returns, survey information and capital market information to support the expected rate of return on plan assets assumption. Refer to “Investment Policy and Strategy for Plan Assets” below for additional information related to Alliant Energy’s, IPL’s and WPL’s investment policy and strategy and mix of assets for the pension and other postretirement benefits plans. Medical cost trend on covered charges - The assumed medical trend rates are critical assumptions in determining the service and interest cost and accumulated postretirement benefit obligation related to postretirement benefits costs. A 1% change in the medical trend rates for 2012, holding all other assumptions constant, would have the following effects (in millions):
| Alliant Energy |  | IPL |  | WPL
| 1% Increase |  | 1% Decrease |  | 1% Increase |  | 1% Decrease |  | 1% Increase |  | 1% Decrease
Effect on total of service and interest cost components |  | $0.4 |  |  |  | ($0.4 | ) |  |  | $0.2 |  |  |  | ($0.2 | ) |  |  | $0.2 |  |  |  | ($0.2 | )
Effect on postretirement benefit obligation | 2.6 |  |  | (2.4 | ) |  | 1.2 |  |  | (1.1 | ) |  | 1.2 |  |  | (1.2 | )
Net Periodic Benefit Costs (Credits) - The components of net periodic benefit costs (credits) for Alliant Energy’s, IPL’s and WPL’s sponsored defined benefit pension and other postretirement benefits plans, and defined benefit pension plans amounts directly assigned to IPL and WPL, are included in the tables below (in millions). In the “IPL” and “WPL” tables below, the qualified defined benefit pension plans costs represent only those respective costs for IPL’s and WPL’s bargaining unit employees covered under the plans that are sponsored by IPL and WPL, respectively. Also in the “IPL” and “WPL” tables below, the other postretirement benefits plans costs (credits) represent costs (credits) for all IPL and WPL employees, respectively. The “Directly assigned defined benefit pension plans” tables below include amounts directly assigned to each of IPL and WPL related to IPL’s and WPL’s current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Alliant Energy | Defined Benefit Pension Plans |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $13.5 |  |  |  | $11.4 |  |  |  | $11.9 |  |  |  | $6.9 |  |  |  | $7.0 |  |  |  | $9.3 |
Interest cost | 51.6 |  |  | 52.0 |  |  | 52.3 |  |  | 10.2 |  |  | 12.3 |  |  | 14.9 |
Expected return on plan assets (b) | (68.8 | ) |  | (63.8 | ) |  | (62.1 | ) |  | (7.5 | ) |  | (7.9 | ) |  | (7.7 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Transition obligation | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |
Prior service cost (credit) | 0.3 |  |  | 0.7 |  |  | 0.9 |  |  | (12.0 | ) |  | (10.0 | ) |  | (2.4 | )
Actuarial loss | 33.3 |  |  | 21.1 |  |  | 23.8 |  |  | 6.3 |  |  | 5.3 |  |  | 7.4 |
Additional benefit costs (d) | 0.1 |  |  | 10.2 |  |  | — |  |  | — |  |  | — |  |  | — |
Settlement losses (e) | 5.4 |  |  | 1.1 |  |  | 1.4 |  |  | — |  |  | — |  |  | — |
|  | $35.4 |  |  |  | $32.7 |  |  |  | $28.2 |  |  |  | $3.9 |  |  |  | $6.7 |  |  |  | $21.6 |
IPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $7.5 |  |  |  | $6.1 |  |  |  | $6.2 |  |  |  | $3.0 |  |  |  | $2.6 |  |  |  | $3.4 |
Interest cost | 17.1 |  |  | 16.7 |  |  | 16.5 |  |  | 4.4 |  |  | 5.5 |  |  | 6.8 |
Expected return on plan assets (b) | (23.0 | ) |  | (20.0 | ) |  | (19.5 | ) |  | (5.1 | ) |  | (5.4 | ) |  | (5.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Transition obligation | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |
Prior service cost (credit) | 0.4 |  |  | 0.5 |  |  | 0.6 |  |  | (6.3 | ) |  | (5.0 | ) |  | (1.1 | )
Actuarial loss | 10.2 |  |  | 5.7 |  |  | 7.2 |  |  | 3.5 |  |  | 2.9 |  |  | 4.0 |
|  | $12.2 |  |  |  | $9.0 |  |  |  | $11.0 |  |  |  | ($0.5 | ) |  |  | $0.6 |  |  |  | $7.9 |
WPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $5.2 |  |  |  | $4.5 |  |  |  | $4.9 |  |  |  | $2.7 |  |  |  | $2.9 |  |  |  | $3.6 |
Interest cost | 16.4 |  |  | 16.1 |  |  | 15.7 |  |  | 4.1 |  |  | 4.9 |  |  | 5.5 |
Expected return on plan assets (b) | (22.3 | ) |  | (20.0 | ) |  | (19.1 | ) |  | (1.3 | ) |  | (1.3 | ) |  | (1.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Prior service cost (credit) | 0.5 |  |  | 0.5 |  |  | 0.5 |  |  | (3.9 | ) |  | (3.4 | ) |  | (0.7 | )
Actuarial loss | 12.1 |  |  | 7.1 |  |  | 8.5 |  |  | 2.3 |  |  | 2.1 |  |  | 2.5 |
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
|  | $12.0 |  |  |  | $8.2 |  |  |  | $10.5 |  |  |  | $3.9 |  |  |  | $5.2 |  |  |  | $9.6 |
Directly assigned defined benefit pension plans | IPL |  | WPL
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Interest cost |  | $7.0 |  |  |  | $7.3 |  |  |  | $7.8 |  |  |  | $5.2 |  |  |  | $5.5 |  |  |  | $5.6 |
Expected return on plan assets (b) | (9.6 | ) |  | (9.7 | ) |  | (9.7 | ) |  | (7.3 | ) |  | (7.3 | ) |  | (7.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Prior service credit | (0.2 | ) |  | (0.2 | ) |  | (0.3 | ) |  | (0.1 | ) |  | (0.2 | ) |  | (0.2 | )
Actuarial loss | 3.9 |  |  | 3.0 |  |  | 2.9 |  |  | 3.6 |  |  | 3.0 |  |  | 2.8 |
Additional benefit costs (d) | — |  |  | 2.8 |  |  | — |  |  | — |  |  | 0.7 |  |  | — |
|  | $1.1 |  |  |  | $3.2 |  |  |  | $0.7 |  |  |  | $1.4 |  |  |  | $1.7 |  |  |  | $0.9 |
(a) | In 2011, Alliant Energy, IPL and WPL amended their defined benefit postretirement health care plans resulting in a revision to the method and level of coverage provided for participants more than 65 years of age. This amendment was determined to be a significant event, which required Alliant Energy, IPL and WPL to remeasure their defined benefit postretirement health care plans in 2011. The amendment resulted in a decrease in Alliant Energy’s, IPL’s and WPL’s postretirement benefit obligations of $55 million, $30 million and $16 million, respectively, in 2011 with the impact of the remeasurement on net periodic benefit costs being recognized prospectively from the remeasurement date. The impact of the remeasurement decreased Alliant Energy’s, IPL’s and WPL’s net periodic benefit costs by $11.3 million, $7.2 million, and $3.8 million in 2011, respectively. The discount rate used for the remeasurement was 5.20%. All other assumptions used for the remeasurement were consistent with the measurement assumptions used at December 31, 2010.
(b) | The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.
(c) | Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan (Cash Balance Plan) where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits. Unrecognized prior service costs (credits) for the postretirement benefits plans are amortized over the average future service period to full eligibility of the participants of each plan.
(d) | Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. The agreement with the IRS required Alliant Energy to amend the Cash Balance Plan, which was completed in 2011 resulting in aggregate additional benefits of $10.2 million paid by Alliant Energy to certain former participants in the Cash Balance Plan in 2011. Alliant Energy recognized $10.2 million of additional benefits costs in 2011 related to these benefits. IPL recognized $6.3 million ($2.8 million directly assigned and $3.5 million allocated by Corporate Services) and WPL recognized $3.4 million ($0.7 million directly assigned and $2.7 million allocated by Corporate Services) of additional benefits costs in 2011 related to these benefits. Refer to Note 13(c) for additional information regarding the Cash Balance Plan.
(e) | Settlement losses related to payments made to retired executives of Alliant Energy.
Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs associated with Corporate Services employees. The following table includes the allocated qualified and non-qualified pension and other postretirement benefits costs associated with Corporate Services employees providing services to IPL and WPL (in millions):
| Pension Benefits Costs (a) |  | Other Postretirement Benefits Costs
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
IPL |  | $4.9 |  |  |  | $5.8 |  |  |  | $2.9 |  |  |  | $0.1 |  |  |  | $0.3 |  |  |  | $2.0 |
WPL | 3.6 |  |  | 4.2 |  |  | 1.9 |  |  | 0.1 |  |  | 0.2 |  |  | 1.3 |
(a) | Includes settlement losses related to payments made to retired executives of Alliant Energy in 2012. In 2011, additional qualified pension benefits costs resulting from the 2011 amendment to the Cash Balance Plan allocated to IPL and WPL by Corporate Services were $3.5 million and $2.7 million, respectively.
The estimated amortization from “Regulatory assets” and “Regulatory liabilities” on the Consolidated Balance Sheets and AOCL on Alliant Energy’s Consolidated Balance Sheet into net periodic benefit cost in 2013 is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
|  |  | Other |  | Qualified |  | Other |  | Qualified |  | Other
| Defined Benefit |  | Postretirement |  | Defined Benefit |  | Postretirement |  | Defined Benefit |  | Postretirement
| Pension Plans |  | Benefits Plans |  | Pension Plan |  | Benefits Plans |  | Pension Plan |  | Benefits Plans
Actuarial loss |  | $36.2 |  |  |  | $4.9 |  |  |  | $10.9 |  |  |  | $2.7 |  |  |  | $13.2 |  |  |  | $1.9 |
Prior service cost (credit) | 0.2 |  |  | (11.9 | ) |  | 0.4 |  |  | (6.3 | ) |  | 0.5 |  |  | (3.9 | )
|  | $36.4 |  |  |  | ($7.0 | ) |  |  | $11.3 |  |  |  | ($3.6 | ) |  |  | $13.7 |  |  |  | ($2.0 | )
Directly assigned defined benefit pension plans | IPL |  | WPL
Actuarial loss |  | $4.2 |  |  |  | $3.9 |
Prior service credit | (0.2 | ) |  | (0.2 | )
|  | $4.0 |  |  |  | $3.7 |
In addition to the estimated amortizations from “Regulatory assets” and “Regulatory liabilities” in the above tables for IPL and WPL, $1.3 million and $0.9 million, respectively, of amortizations are expected in 2013 from “Regulatory assets” and “Regulatory liabilities” associated with Corporate Services employees participating in other Alliant Energy sponsored plans allocated to IPL and WPL. Alliant Energy’s, IPL’s and WPL’s net periodic benefit costs are primarily included in “Utility - Other operation and maintenance” in the Consolidated Statements of Income. Benefit Plan Assets and Obligations - A reconciliation of the funded status of Alliant Energy’s qualified and non-qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on Alliant Energy’s Consolidated Balance Sheets at December 31 was as follows (in millions):
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $1,081.4 |  |  |  | $953.0 |  |  |  | $224.2 |  |  |  | $274.9 |
Service cost | 13.5 |  |  | 11.4 |  |  | 6.9 |  |  | 7.0 |
Interest cost | 51.6 |  |  | 52.0 |  |  | 10.2 |  |  | 12.3 |
Plan participants’ contributions | — |  |  | — |  |  | 2.7 |  |  | 6.4 |
Plan amendments (a) | — |  |  | 10.2 |  |  | — |  |  | (56.6 | )
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |
Actuarial (gain) loss | 135.4 |  |  | 126.2 |  |  | (1.6 | ) |  | (0.8 | )
Early Retiree Reinsurance Program (ERRP) proceeds | — |  |  | — |  |  | — |  |  | 0.6 |
Gross benefits paid | (74.5 | ) |  | (71.4 | ) |  | (19.2 | ) |  | (20.8 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 1.2 |
Net projected benefit obligation at December 31 | 1,207.5 |  |  | 1,081.4 |  |  | 223.2 |  |  | 224.2 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 897.4 |  |  | 823.0 |  |  | 120.4 |  |  | 122.7 |
Actual return on plan assets | 126.9 |  |  | 28.9 |  |  | 14.3 |  |  | 2.6 |
Employer contributions | 15.8 |  |  | 116.9 |  |  | 4.9 |  |  | 9.5 |
Plan participants’ contributions | — |  |  | — |  |  | 2.7 |  |  | 6.4 |
Gross benefits paid | (74.5 | ) |  | (71.4 | ) |  | (19.2 | ) |  | (20.8 | )
Fair value of plan assets at December 31 | 965.6 |  |  | 897.4 |  |  | 123.1 |  |  | 120.4 |
Under funded status at December 31 |  | ($241.9 | ) |  |  | ($184.0 | ) |  |  | ($100.1 | ) |  |  | ($103.8 | )
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Non-current assets |  | $— |  |  |  | $— |  |  |  | $3.5 |  |  |  | $1.3 |
Other current liabilities | (2.4 | ) |  | (4.6 | ) |  | (2.8 | ) |  | — |
Pension and other benefit obligations | (239.5 | ) |  | (179.4 | ) |  | (100.8 | ) |  | (105.1 | )
Net amount recognized at December 31 |  | ($241.9 | ) |  |  | ($184.0 | ) |  |  | ($100.1 | ) |  |  | ($103.8 | )
Amounts recognized in Regulatory Assets, Regulatory Liabilities and AOCL consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $533.4 |  |  |  | $494.8 |  |  |  | $62.1 |  |  |  | $76.7 |
Prior service credit | (7.2 | ) |  | (6.9 | ) |  | (40.5 | ) |  | (52.5 | )
|  | $526.2 |  |  |  | $487.9 |  |  |  | $21.6 |  |  |  | $24.2 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) and Alliant Energy’s Consolidated Statements of Common Equity for amounts recognized in “Regulatory assets” and “AOCL,” respectively, on Alliant Energy’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $2.7 million and $3.3 million, respectively, of regulatory liabilities were recognized related to Alliant Energy’s other postretirement benefits plans.
A reconciliation of the funded status of IPL’s sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on IPL’s Consolidated Balance Sheets, at December 31 was as follows (in millions):
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $344.5 |  |  |  | $293.8 |  |  |  | $97.5 |  |  |  | $128.5 |
Service cost | 7.5 |  |  | 6.1 |  |  | 3.0 |  |  | 2.6 |
Interest cost | 17.1 |  |  | 16.7 |  |  | 4.4 |  |  | 5.5 |
Plan participants’ contributions | — |  |  | — |  |  | 0.9 |  |  | 2.0 |
Plan amendments (a) | — |  |  | — |  |  | — |  |  | (30.1 | )
Actuarial (gain) loss | 38.2 |  |  | 45.2 |  |  | (1.4 | ) |  | (2.7 | )
ERRP proceeds | — |  |  | — |  |  | — |  |  | 0.2 |
Gross benefits paid | (18.9 | ) |  | (17.3 | ) |  | (8.4 | ) |  | (9.1 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 0.6 |
Net projected benefit obligation at December 31 | 388.4 |  |  | 344.5 |  |  | 96.0 |  |  | 97.5 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 298.7 |  |  | 256.9 |  |  | 74.7 |  |  | 77.5 |
Actual return on plan assets | 42.5 |  |  | 9.1 |  |  | 9.4 |  |  | 1.4 |
Employer contributions | — |  |  | 50.0 |  |  | 2.2 |  |  | 2.9 |
Plan participants’ contributions | — |  |  | — |  |  | 0.9 |  |  | 2.0 |
Gross benefits paid | (18.9 | ) |  | (17.3 | ) |  | (8.4 | ) |  | (9.1 | )
Fair value of plan assets at December 31 | 322.3 |  |  | 298.7 |  |  | 78.8 |  |  | 74.7 |
Under funded status at December 31 |  | ($66.1 | ) |  |  | ($45.8 | ) |  |  | ($17.2 | ) |  |  | ($22.8 | )
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Pension and other benefit obligations |  | ($66.1 | ) |  |  | ($45.8 | ) |  |  | ($17.2 | ) |  |  | ($22.8 | )
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $149.7 |  |  |  | $141.1 |  |  |  | $32.0 |  |  |  | $41.0 |
Prior service cost (credit) | 0.7 |  |  | 1.1 |  |  | (21.3 | ) |  | (27.6 | )
|  | $150.4 |  |  |  | $142.2 |  |  |  | $10.7 |  |  |  | $13.4 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on IPL’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $1.4 million and $2.8 million, respectively, of regulatory liabilities were recognized related to IPL’s other postretirement benefits plans.
A reconciliation of the funded status of WPL’s sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on WPL’s Consolidated Balance Sheets, at December 31 was as follows (in millions):
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $332.5 |  |  |  | $283.3 |  |  |  | $89.6 |  |  |  | $103.3 |
Service cost | 5.2 |  |  | 4.5 |  |  | 2.7 |  |  | 2.9 |
Interest cost | 16.4 |  |  | 16.1 |  |  | 4.1 |  |  | 4.9 |
Plan participants’ contributions | — |  |  | — |  |  | 1.2 |  |  | 3.3 |
Plan amendments (a) | — |  |  | — |  |  | — |  |  | (18.2 | )
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |
Actuarial loss | 43.4 |  |  | 43.3 |  |  | 0.3 |  |  | 2.3 |
ERRP proceeds | — |  |  | — |  |  | — |  |  | 0.2 |
Gross benefits paid | (17.4 | ) |  | (14.7 | ) |  | (8.8 | ) |  | (9.6 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 0.5 |
Net projected benefit obligation at December 31 | 380.2 |  |  | 332.5 |  |  | 89.1 |  |  | 89.6 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 289.6 |  |  | 255.2 |  |  | 25.1 |  |  | 25.0 |
Actual return on plan assets | 41.0 |  |  | 9.1 |  |  | 2.5 |  |  | 0.9 |
Employer contributions | — |  |  | 40.0 |  |  | 2.3 |  |  | 5.5 |
Plan participants’ contributions | — |  |  | — |  |  | 1.2 |  |  | 3.3 |
Gross benefits paid | (17.4 | ) |  | (14.7 | ) |  | (8.8 | ) |  | (9.6 | )
Fair value of plan assets at December 31 | 313.2 |  |  | 289.6 |  |  | 22.3 |  |  | 25.1 |
Under funded status at December 31 |  | ($67.0 | ) |  |  | ($42.9 | ) |  |  | ($66.8 | ) |  |  | ($64.5 | )
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Non-current assets |  | $— |  |  |  | $— |  |  |  | $3.5 |  |  |  | $1.3 |
Other current liabilities | — |  |  | — |  |  | (2.8 | ) |  | — |
Pension and other benefit obligations | (67.0 | ) |  | (42.9 | ) |  | (67.5 | ) |  | (65.8 | )
Net amount recognized at December 31 |  | ($67.0 | ) |  |  | ($42.9 | ) |  |  | ($66.8 | ) |  |  | ($64.5 | )
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $155.3 |  |  |  | $142.7 |  |  |  | $24.3 |  |  |  | $27.8 |
Prior service cost (credit) | 1.9 |  |  | 2.4 |  |  | (13.4 | ) |  | (17.3 | )
|  | $157.2 |  |  |  | $145.1 |  |  |  | $10.9 |  |  |  | $10.5 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on WPL’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $0.2 million and $0, respectively, of regulatory liabilities were recognized related to WPL’s other postretirement benefits plans.
Included in the following tables are accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and other postretirement benefits plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the December 31 measurement date (Not Applicable (N/A); in millions):
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $1,155.5 |  |  |  | $1,029.4 |  |  |  | $223.2 |  |  |  | $224.2 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 1,155.5 |  |  | 1,029.4 |  |  | 223.2 |  |  | 224.2 |
Fair value of plan assets | 965.6 |  |  | 897.4 |  |  | 123.1 |  |  | 120.4 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 1,207.5 |  |  | 1,081.4 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 965.6 |  |  | 897.4 |  |  | N/A |  |  | N/A |
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $359.6 |  |  |  | $314.6 |  |  |  | $96.0 |  |  |  | $97.5 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 359.6 |  |  | 314.6 |  |  | 96.0 |  |  | 97.5 |
Fair value of plan assets | 322.3 |  |  | 298.7 |  |  | 78.8 |  |  | 74.7 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 388.4 |  |  | 344.5 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 322.3 |  |  | 298.7 |  |  | N/A |  |  | N/A |
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $363.7 |  |  |  | $314.7 |  |  |  | $89.1 |  |  |  | $89.6 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 363.7 |  |  | 314.7 |  |  | 89.1 |  |  | 89.6 |
Fair value of plan assets | 313.2 |  |  | 289.6 |  |  | 22.3 |  |  | 25.1 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 380.2 |  |  | 332.5 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 313.2 |  |  | 289.6 |  |  | N/A |  |  | N/A |
The “Directly assigned defined benefit pension plans” table below includes amounts directly assigned to each of IPL and WPL related to their current and former non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. A reconciliation of the funded status of the directly assigned qualified and non-qualified defined benefit pension plans to the amounts recognized on IPL’s and WPL’s Consolidated Balance Sheets at December 31 was as follows (in millions):
Directly assigned defined benefit pension plans | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $155.4 |  |  |  | $144.4 |  |  |  | $115.2 |  |  |  | $107.4 |
Interest cost | 7.0 |  |  | 7.3 |  |  | 5.2 |  |  | 5.5 |
Plan amendments | — |  |  | 2.8 |  |  | — |  |  | 0.7 |
Actuarial loss | 17.9 |  |  | 13.2 |  |  | 14.5 |  |  | 10.3 |
Gross benefits paid | (9.5 | ) |  | (12.3 | ) |  | (8.4 | ) |  | (8.7 | )
Net projected benefit obligation at December 31 | 170.8 |  |  | 155.4 |  |  | 126.5 |  |  | 115.2 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 127.4 |  |  | 127.6 |  |  | 97.0 |  |  | 95.6 |
Actual return on plan assets | 17.9 |  |  | 4.2 |  |  | 13.5 |  |  | 3.2 |
Employer contributions | 0.7 |  |  | 7.9 |  |  | 0.1 |  |  | 6.9 |
Gross benefits paid | (9.5 | ) |  | (12.3 | ) |  | (8.4 | ) |  | (8.7 | )
Fair value of plan assets at December 31 | 136.5 |  |  | 127.4 |  |  | 102.2 |  |  | 97.0 |
Under funded status at December 31 |  | ($34.3 | ) |  |  | ($28.0 | ) |  |  | ($24.3 | ) |  |  | ($18.2 | )
Directly assigned defined benefit pension plans | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Other current liabilities |  | ($0.8 | ) |  |  | ($0.8 | ) |  |  | ($0.2 | ) |  |  | ($0.2 | )
Pension and other benefit obligations | (33.5 | ) |  | (27.2 | ) |  | (24.1 | ) |  | (18.0 | )
Net amount recognized at December 31 |  | ($34.3 | ) |  |  | ($28.0 | ) |  |  | ($24.3 | ) |  |  | ($18.2 | )
Amounts recognized in Regulatory Assets (a): |  |  |  |  |  |  |
Net actuarial loss |  | $81.9 |  |  |  | $76.2 |  |  |  | $78.4 |  |  |  | $73.7 |
Prior service credit | (3.2 | ) |  | (3.4 | ) |  | (2.3 | ) |  | (2.4 | )
|  | $78.7 |  |  |  | $72.8 |  |  |  | $76.1 |  |  |  | $71.3 |
Accumulated benefit obligations |  | $170.8 |  |  |  | $155.4 |  |  |  | $126.5 |  |  |  | $115.2 |
(a) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on IPL’s and WPL’s Consolidated Balance Sheets.
In addition to the amounts recognized in “Regulatory assets and regulatory liabilities” in the above tables for IPL and WPL, “Regulatory assets” and “Regulatory liabilities” were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at December 31 as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Regulatory assets |  | $38.1 |  |  |  | $33.7 |  |  |  | $25.5 |  |  |  | $22.3 |
Regulatory liabilities | 0.6 |  |  | 0.3 |  |  | 0.4 |  |  | 0.2 |
Estimated Future Employer Contributions and Benefit Payments - Alliant Energy, IPL and WPL estimate that funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans, and the directly assigned qualified and non-qualified defined benefit pension plans amounts, during 2013 will be as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Qualified defined benefit pension plans |  | $— |  |  |  | $— |  |  |  | $— |
Non-qualified defined benefit pension plans (a) | 2.4 |  |  | N/A |  |  | N/A |
Directly assigned defined benefit pension plans (b) | N/A |  |  | 0.8 |  |  | 0.2 |
Other postretirement benefits plans | 3.0 |  |  | — |  |  | 3.0 |
(a) | Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans.
(b) | Amounts directly assigned to IPL and WPL for non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Expected benefit payments, and the directly assigned qualified and non-qualified defined benefit pension benefits amounts, which reflect expected future service, as appropriate, are as follows (in millions):
Alliant Energy | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified and non-qualified defined benefit pension benefits |  | $61.9 |  |  |  | $64.7 |  |  |  | $68.5 |  |  |  | $66.6 |  |  |  | $69.2 |  |  |  | $374.1 |
Other postretirement benefits | 16.6 |  |  | 16.2 |  |  | 16.3 |  |  | 16.4 |  |  | 16.6 |  |  | 84.2 |
|  | $78.5 |  |  |  | $80.9 |  |  |  | $84.8 |  |  |  | $83.0 |  |  |  | $85.8 |  |  |  | $458.3 |
IPL | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified defined benefit pension benefits |  | $15.9 |  |  |  | $16.9 |  |  |  | $17.9 |  |  |  | $18.9 |  |  |  | $20.0 |  |  |  | $116.0 |
Directly assigned defined benefit pension benefits | 12.6 |  |  | 13.4 |  |  | 14.1 |  |  | 12.1 |  |  | 13.5 |  |  | 60.2 |
Other postretirement benefits | 8.0 |  |  | 7.3 |  |  | 7.2 |  |  | 7.1 |  |  | 7.2 |  |  | 35.9 |
|  | $36.5 |  |  |  | $37.6 |  |  |  | $39.2 |  |  |  | $38.1 |  |  |  | $40.7 |  |  |  | $212.1 |
WPL | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified defined benefit pension benefits |  | $14.4 |  |  |  | $15.2 |  |  |  | $16.1 |  |  |  | $17.0 |  |  |  | $18.0 |  |  |  | $108.7 |
Directly assigned defined benefit pension benefits | 10.5 |  |  | 10.2 |  |  | 11.4 |  |  | 9.8 |  |  | 9.5 |  |  | 43.0 |
Other postretirement benefits | 6.3 |  |  | 6.5 |  |  | 6.7 |  |  | 6.7 |  |  | 6.8 |  |  | 34.3 |
|  | $31.2 |  |  |  | $31.9 |  |  |  | $34.2 |  |  |  | $33.5 |  |  |  | $34.3 |  |  |  | $186.0 |
Investment Policy and Strategy for Plan Assets - Alliant Energy’s, IPL’s and WPL’s investment policies and their strategies employed with respect to assets of defined benefit pension and other postretirement benefits plans are to combine both preservation of principal and prudent and reasonable risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. It is recognized that risk and volatility are present with all types of investments. However, risk is mitigated at the total fund level through diversification by asset class including both U.S. and international equity exposure, the number of individual investments, and sector and industry limits. Defined Benefit Pension Plans Assets - For assets of defined benefit pension plans, the mix among asset classes is controlled by long-term asset allocation targets. Historical performance results and future expectations suggest that equity securities will provide higher total investment returns than debt securities over a long-term investment horizon. Consistent with the goals of meeting obligations to plan participants and minimizing benefit costs over the long-term, the defined benefit pension plans have a long-term investment posture more heavily weighted towards equity holdings. The asset allocation is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. Alliant Energy, IPL and WPL also use an overlay management service to help maintain target allocations and liquidity needs. The overlay manager is authorized to use derivative financial instruments to facilitate this service. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, margin trading, oil and gas limited partnerships and securities of the managers’ firms or affiliate firms. If the investment vehicle is a commingled account or mutual fund, it is not possible to place restrictions on any aspect of fund management. At December 31, 2012, the current target ranges and actual allocations for Alliant Energy’s, IPL’s and WPL’s defined benefit pension plan assets were as follows:
| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | — | % | - | 5% |  | 4%
Equity securities: |  |  |  |  |
U.S. large cap core | 10 | % | - | 20% |  | 13%
U.S. large cap value | 6 | % | - | 16% |  | 11%
U.S. large cap growth | 6 | % | - | 16% |  | 11%
U.S. small cap value | — | % | - | 6% |  | 3%
U.S. small cap growth | — | % | - | 6% |  | 3%
International - developed markets | 11 | % | - | 23% |  | 16%
International - emerging markets | — | % | - | 8% |  | 4%
Global asset allocation securities | 5 | % | - | 15% |  | 10%
Fixed income securities | 15 | % | - | 35% |  | 25%
Other Postretirement Benefits Plans Assets - Other postretirement benefits plans assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in Voluntary Employees’ Beneficiary Association (VEBA) trusts. The investment policy and strategy of the 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. For VEBA trusts with assets greater than $5 million, the mix among asset classes is controlled by long-term allocation targets. The asset allocation is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, margin trading, oil and gas limited partnerships and securities of the managers’ firms or affiliate firms. If the investment vehicle is a commingled account or mutual fund, it is not possible to place restrictions on any aspect of fund management. At December 31, 2012, the current target ranges and actual allocations for Alliant Energy’s, IPL’s and WPL’s VEBA trusts with assets greater than $5 million were as follows:
| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | — | % | - | 5% |  | 2%
Equity securities: |  |  |  |  |
Domestic | 25 | % | - | 45% |  | 34%
International | 10 | % | - | 20% |  | 15%
Global asset allocation securities | 20 | % | - | 40% |  | 29%
Fixed income securities | 10 | % | - | 30% |  | 20%
Securities Lending Program - Alliant Energy, IPL and WPL have a securities lending program with a third-party agent that allows the agent to lend certain securities from their defined benefit pension and other postretirement benefits plans to selected entities against receipt of collateral (in the form of cash, government and agency securities or letters of credit) as provided for and determined in accordance with its securities lending agency agreement. Initial collateral levels are no less than 100% of the market value of loans to non-affiliated borrowers of U.S. government securities; 102% of the market value of loans to affiliated borrowers of U.S. government securities; 102% of the market value of loans on U.S. corporate bonds and U.S. equity securities; 105% of the market value of loans on non-U.S. securities; and 102% of the market value of loans on all other securities. Refer to “Fair Value Measurements” below for details of fair value of invested collateral and amounts due to borrowers for the securities lending program. Fair Value Measurements - The following tables report a framework for measuring fair value. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows: Level 1 - Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. Alliant Energy’s, IPL’s and WPL’s investments in equity and fixed income securities held in registered investment companies and directly held equity securities are valued at the closing price reported in the active market in which the securities are traded. Level 2 - Pricing inputs are quoted prices for similar asset or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Alliant Energy’s, IPL’s and WPL’s investments in corporate bonds and government and agency obligations are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Alliant Energy’s, IPL’s and WPL’s investments in equity and fixed income securities in common/collective trusts are valued at the net asset value of shares held by the plans, which is based on the fair market value of the underlying investments in equity and fixed income securities of the common/collective trusts. Level 2 plan assets also consist of asset backed securities within their securities lending invested collateral. Level 3 - Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. Alliant Energy’s, IPL’s and WPL’s Level 3 plan assets include certain asset backed securities and corporate bonds within their securities lending invested collateral. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while Alliant Energy, IPL and WPL believe their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. At December 31, the fair values of Alliant Energy’s qualified and non-qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):
Alliant Energy | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $43.9 |  |  |  | $— |  |  |  | $43.9 |  |  |  | $— |  |  |  | $117.5 |  |  |  | $117.5 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 129.0 |  |  | 129.0 |  |  | — |  |  | — |  |  | 110.7 |  |  | 110.7 |  |  | — |  |  | — |
U.S. large cap value | 107.9 |  |  | — |  |  | 107.9 |  |  | — |  |  | 91.6 |  |  | — |  |  | 91.6 |  |  | — |
U.S. large cap growth | 105.8 |  |  | — |  |  | 105.8 |  |  | — |  |  | 91.5 |  |  | — |  |  | 91.5 |  |  | — |
U.S. small cap value | 30.4 |  |  | — |  |  | 30.4 |  |  | — |  |  | 25.7 |  |  | — |  |  | 25.7 |  |  | — |
U.S. small cap growth | 25.0 |  |  | 25.0 |  |  | — |  |  | — |  |  | 21.7 |  |  | 21.7 |  |  | — |  |  | — |
International - developed markets | 153.7 |  |  | 80.3 |  |  | 73.4 |  |  | — |  |  | 126.4 |  |  | 65.4 |  |  | 61.0 |  |  | — |
International - emerging markets | 38.5 |  |  | 38.5 |  |  | — |  |  | — |  |  | 30.4 |  |  | 30.4 |  |  | — |  |  | — |
Global asset allocation securities | 94.5 |  |  | 56.3 |  |  | 38.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 30.7 |  |  | — |  |  | 30.7 |  |  | — |  |  | 57.1 |  |  | — |  |  | 57.1 |  |  | — |
Government and agency obligations | 49.2 |  |  | — |  |  | 49.2 |  |  | — |  |  | 87.8 |  |  | — |  |  | 87.8 |  |  | — |
Fixed income funds | 162.6 |  |  | 0.2 |  |  | 162.4 |  |  | — |  |  | 146.7 |  |  | 0.2 |  |  | 146.5 |  |  | — |
Securities lending invested collateral | 4.4 |  |  | — |  |  | 2.9 |  |  | 1.5 |  |  | 9.3 |  |  | 4.7 |  |  | 2.8 |  |  | 1.8 |
| 975.6 |  |  |  | $329.3 |  |  |  | $644.8 |  |  |  | $1.5 |  |  | 916.4 |  |  |  | $350.6 |  |  |  | $564.0 |  |  |  | $1.8 |
Accrued investment income | 0.6 |  |  |  |  |  |  |  |  | 1.0 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (1.5 | ) |  |  |  |  |  |  |  | (4.7 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (9.1 | ) |  |  |  |  |  |  |  | (15.3 | ) |  |  |  |  |  |
Total pension plan assets |  | $965.6 |  |  |  |  |  |  |  |  |  | $897.4 |  |  |  |  |  |  |
At December 31, the fair values of IPL’s and WPL’s qualified and non-qualified defined benefit pension plan assets associated with IPL’s and WPL’s current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored plans that were directly assigned to IPL and WPL, along with the percentage these assets represent of the fair values by asset category and fair value hierarchy level shown in the above table were as follows (dollars in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Fair values of directly assigned amounts | $136.5 |  | $127.4 |  | $102.2 |  | $97.0
Percentage represented | 14.1% |  | 14.2% |  | 10.6% |  | 10.8%
At December 31, the fair values of IPL’s qualified defined benefit pension plan assets by asset category and fair value hierarchy level were as follows (in millions):
IPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $14.6 |  |  |  | $— |  |  |  | $14.6 |  |  |  | $— |  |  |  | $39.1 |  |  |  | $39.1 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 43.1 |  |  | 43.1 |  |  | — |  |  | — |  |  | 36.8 |  |  | 36.8 |  |  | — |  |  | — |
U.S. large cap value | 36.0 |  |  | — |  |  | 36.0 |  |  | — |  |  | 30.5 |  |  | — |  |  | 30.5 |  |  | — |
U.S. large cap growth | 35.3 |  |  | — |  |  | 35.3 |  |  | — |  |  | 30.5 |  |  | — |  |  | 30.5 |  |  | — |
U.S. small cap value | 10.2 |  |  | — |  |  | 10.2 |  |  | — |  |  | 8.6 |  |  | — |  |  | 8.6 |  |  | — |
U.S. small cap growth | 8.3 |  |  | 8.3 |  |  | — |  |  | — |  |  | 7.2 |  |  | 7.2 |  |  | — |  |  | — |
International - developed markets | 51.3 |  |  | 26.8 |  |  | 24.5 |  |  | — |  |  | 42.1 |  |  | 21.8 |  |  | 20.3 |  |  | — |
International - emerging markets | 12.9 |  |  | 12.9 |  |  | — |  |  | — |  |  | 10.1 |  |  | 10.1 |  |  | — |  |  | — |
Global asset allocation securities | 31.5 |  |  | 18.8 |  |  | 12.7 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 10.2 |  |  | — |  |  | 10.2 |  |  | — |  |  | 19.0 |  |  | — |  |  | 19.0 |  |  | — |
Government and agency obligations | 16.4 |  |  | — |  |  | 16.4 |  |  | — |  |  | 29.2 |  |  | — |  |  | 29.2 |  |  | — |
Fixed income funds | 54.3 |  |  | 0.1 |  |  | 54.2 |  |  | — |  |  | 48.8 |  |  | 0.1 |  |  | 48.7 |  |  | — |
Securities lending invested collateral | 1.5 |  |  | — |  |  | 1.0 |  |  | 0.5 |  |  | 3.1 |  |  | 1.6 |  |  | 0.9 |  |  | 0.6 |
| 325.6 |  |  |  | $110.0 |  |  |  | $215.1 |  |  |  | $0.5 |  |  | 305.0 |  |  |  | $116.7 |  |  |  | $187.7 |  |  |  | $0.6 |
Accrued investment income | 0.2 |  |  |  |  |  |  |  |  | 0.4 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (0.5 | ) |  |  |  |  |  |  |  | (1.6 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (3.0 | ) |  |  |  |  |  |  |  | (5.1 | ) |  |  |  |  |  |
Total pension plan assets |  | $322.3 |  |  |  |  |  |  |  |  |  | $298.7 |  |  |  |  |  |  |
At December 31, the fair values of WPL’s qualified defined benefit pension plan assets by asset category and fair value hierarchy level were as follows (in millions):
WPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $14.2 |  |  |  | $— |  |  |  | $14.2 |  |  |  | $— |  |  |  | $37.9 |  |  |  | $37.9 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 41.8 |  |  | 41.8 |  |  | — |  |  | — |  |  | 35.7 |  |  | 35.7 |  |  | — |  |  | — |
U.S. large cap value | 35.0 |  |  | — |  |  | 35.0 |  |  | — |  |  | 29.6 |  |  | — |  |  | 29.6 |  |  | — |
U.S. large cap growth | 34.3 |  |  | — |  |  | 34.3 |  |  | — |  |  | 29.5 |  |  | — |  |  | 29.5 |  |  | — |
U.S. small cap value | 9.9 |  |  | — |  |  | 9.9 |  |  | — |  |  | 8.3 |  |  | — |  |  | 8.3 |  |  | — |
U.S. small cap growth | 8.1 |  |  | 8.1 |  |  | — |  |  | — |  |  | 7.0 |  |  | 7.0 |  |  | — |  |  | — |
International - developed markets | 49.9 |  |  | 26.1 |  |  | 23.8 |  |  | — |  |  | 40.8 |  |  | 21.1 |  |  | 19.7 |  |  | — |
International - emerging markets | 12.5 |  |  | 12.5 |  |  | — |  |  | — |  |  | 9.8 |  |  | 9.8 |  |  | — |  |  | — |
Global asset allocation securities | 30.7 |  |  | 18.3 |  |  | 12.4 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 9.9 |  |  | — |  |  | 9.9 |  |  | — |  |  | 18.4 |  |  | — |  |  | 18.4 |  |  | — |
Government and agency obligations | 16.0 |  |  | — |  |  | 16.0 |  |  | — |  |  | 28.3 |  |  | — |  |  | 28.3 |  |  | — |
Fixed income funds | 52.8 |  |  | 0.1 |  |  | 52.7 |  |  | — |  |  | 47.4 |  |  | 0.1 |  |  | 47.3 |  |  | — |
Securities lending invested collateral | 1.4 |  |  | — |  |  | 0.9 |  |  | 0.5 |  |  | 3.0 |  |  | 1.5 |  |  | 0.9 |  |  | 0.6 |
| 316.5 |  |  |  | $106.9 |  |  |  | $209.1 |  |  |  | $0.5 |  |  | 295.7 |  |  |  | $113.1 |  |  |  | $182.0 |  |  |  | $0.6 |
Accrued investment income | 0.2 |  |  |  |  |  |  |  |  | 0.3 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (0.5 | ) |  |  |  |  |  |  |  | (1.5 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (3.0 | ) |  |  |  |  |  |  |  | (4.9 | ) |  |  |  |  |  |
Total pension plan assets |  | $313.2 |  |  |  |  |  |  |  |  |  | $289.6 |  |  |  |  |  |  |
At December 31, the fair values of other postretirement benefits plans assets by asset category and fair value hierarchy level were as follows (in millions):
Alliant Energy | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $8.4 |  |  |  | $— |  |  |  | $8.4 |  |  |  | $— |  |  |  | $14.0 |  |  |  | $14.0 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 32.9 |  |  | 32.9 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 2.8 |  |  | 2.8 |  |  | — |  |  | — |  |  | 37.1 |  |  | 37.1 |  |  | — |  |  | — |
U.S. large cap value | 2.4 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |
U.S. large cap growth | 2.3 |  |  | — |  |  | 2.3 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |
U.S. mid cap core | — |  |  | — |  |  | — |  |  | — |  |  | 17.8 |  |  | 17.8 |  |  | — |  |  | — |
U.S. small cap core | — |  |  | — |  |  | — |  |  | — |  |  | 4.7 |  |  | 4.7 |  |  | — |  |  | — |
U.S. small cap value | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.6 |  |  | — |  |  | 0.6 |  |  | — |
U.S. small cap growth | 0.6 |  |  | 0.6 |  |  | — |  |  | — |  |  | 0.5 |  |  | 0.5 |  |  | — |  |  | — |
International - blend | 14.3 |  |  | 14.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 3.4 |  |  | 1.8 |  |  | 1.6 |  |  | — |  |  | 3.3 |  |  | 1.7 |  |  | 1.6 |  |  | — |
International - emerging markets | 0.8 |  |  | 0.8 |  |  | — |  |  | — |  |  | 0.8 |  |  | 0.8 |  |  | — |  |  | — |
Global asset allocation securities | 30.4 |  |  | 29.6 |  |  | 0.8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 6.1 |  |  | — |  |  | 6.1 |  |  | — |
Government and agency obligations | 1.1 |  |  | — |  |  | 1.1 |  |  | — |  |  | 5.6 |  |  | — |  |  | 5.6 |  |  | — |
Fixed income funds | 22.4 |  |  | 18.8 |  |  | 3.6 |  |  | — |  |  | 25.4 |  |  | 21.6 |  |  | 3.8 |  |  | — |
Securities lending invested collateral | 0.1 |  |  | — |  |  | 0.1 |  |  | — |  |  | 0.4 |  |  | 0.2 |  |  | 0.1 |  |  | 0.1 |
| 123.3 |  |  |  | $101.6 |  |  |  | $21.7 |  |  |  | $— |  |  | 121.1 |  |  |  | $98.4 |  |  |  | $22.6 |  |  |  | $0.1 |
Accrued investment income | — |  |  |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | — |  |  |  |  |  |  |  |  | (0.2 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (0.2 | ) |  |  |  |  |  |  |  | (0.6 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $123.1 |  |  |  |  |  |  |  |  |  | $120.4 |  |  |  |  |  |  |
IPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $3.3 |  |  |  | $— |  |  |  | $3.3 |  |  |  | $— |  |  |  | $2.1 |  |  |  | $2.1 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 24.3 |  |  | 24.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 0.8 |  |  | 0.8 |  |  | — |  |  | — |  |  | 29.3 |  |  | 29.3 |  |  | — |  |  | — |
U.S. large cap value | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.8 |  |  | — |  |  | 0.8 |  |  | — |
U.S. large cap growth | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.8 |  |  | — |  |  | 0.8 |  |  | — |
U.S. mid cap core | — |  |  | — |  |  | — |  |  | — |  |  | 14.7 |  |  | 14.7 |  |  | — |  |  | — |
U.S. small cap value | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 0.2 |  |  | — |
U.S. small cap growth | 0.2 |  |  | 0.2 |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.2 |  |  | — |  |  | — |
International - blend | 10.6 |  |  | 10.6 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 1.0 |  |  | 0.5 |  |  | 0.5 |  |  | — |  |  | 1.2 |  |  | 0.6 |  |  | 0.6 |  |  | — |
International - emerging markets | 0.2 |  |  | 0.2 |  |  | — |  |  | — |  |  | 0.3 |  |  | 0.3 |  |  | — |  |  | — |
Global asset allocation securities | 21.5 |  |  | 21.3 |  |  | 0.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 4.6 |  |  | — |  |  | 4.6 |  |  | — |
Government and agency obligations | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 4.1 |  |  | — |  |  | 4.1 |  |  | — |
Fixed income funds | 14.9 |  |  | 13.9 |  |  | 1.0 |  |  | — |  |  | 16.5 |  |  | 15.1 |  |  | 1.4 |  |  | — |
Securities lending invested collateral | — |  |  | — |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.1 |  |  | 0.1 |  |  | — |
| 78.9 |  |  |  | $71.8 |  |  |  | $7.1 |  |  |  | $— |  |  | 75.0 |  |  |  | $62.4 |  |  |  | $12.6 |  |  |  | $— |
Accrued investment income | — |  |  |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |
Due to borrowers for securities lending program | (0.1 | ) |  |  |  |  |  |  |  | (0.4 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $78.8 |  |  |  |  |  |  |  |  |  | $74.7 |  |  |  |  |  |  |
WPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $3.9 |  |  |  | $— |  |  |  | $3.9 |  |  |  | $— |  |  |  | $10.5 |  |  |  | $10.5 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 3.1 |  |  | 3.1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 1.3 |  |  | 1.3 |  |  | — |  |  | — |  |  | 1.2 |  |  | 1.2 |  |  | — |  |  | — |
U.S. large cap value | 1.2 |  |  | — |  |  | 1.2 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
U.S. large cap growth | 1.1 |  |  | — |  |  | 1.1 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
U.S. small cap core | — |  |  | — |  |  | — |  |  | — |  |  | 4.7 |  |  | 4.7 |  |  | — |  |  | — |
U.S. small cap value | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 0.3 |  |  | — |
U.S. small cap growth | 0.3 |  |  | 0.3 |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.2 |  |  | — |  |  | — |
International - blend | 1.3 |  |  | 1.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 1.6 |  |  | 0.8 |  |  | 0.8 |  |  | — |  |  | 1.3 |  |  | 0.7 |  |  | 0.6 |  |  | — |
International - emerging markets | 0.4 |  |  | 0.4 |  |  | — |  |  | — |  |  | 0.3 |  |  | 0.3 |  |  | — |  |  | — |
Global asset allocation securities | 3.6 |  |  | 3.2 |  |  | 0.4 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 1.1 |  |  | — |  |  | 1.1 |  |  | — |
Government and agency obligations | 0.5 |  |  | — |  |  | 0.5 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
Fixed income funds | 3.5 |  |  | 1.8 |  |  | 1.7 |  |  | — |  |  | 2.6 |  |  | 1.0 |  |  | 1.6 |  |  | — |
Securities lending invested collateral | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |  |  | 0.1 |  |  | — |  |  | — |
| 22.4 |  |  |  | $12.2 |  |  |  | $10.2 |  |  |  | $— |  |  | 25.3 |  |  |  | $18.7 |  |  |  | $6.6 |  |  |  | $— |
Due to brokers, net (pending trades with brokers) | — |  |  |  |  |  |  |  |  | (0.1 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (0.1 | ) |  |  |  |  |  |  |  | (0.1 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $22.3 |  |  |  |  |  |  |  |  |  | $25.1 |  |  |  |  |  |  |
For the various defined benefit pension and other postretirement benefits plans, Alliant Energy common stock represented less than 1% of total plan assets at December 31, 2012 and 2011. Cash Balance Plan - Alliant Energy’s defined benefit pension plans include the Cash Balance Plan that provides benefits for certain non-bargaining unit employees. The Cash Balance Plan has been closed to new hires since 2005. Effective 2008, Alliant Energy amended the Cash Balance Plan by discontinuing additional contributions into employees’ Cash Balance Plan accounts and increased its level of contributions to its 401(k) Savings Plan. In 2009, Alliant Energy amended the Cash Balance Plan by changing participants’ future interest credit formula to use the annual change in the consumer price index. This amendment provides participants an interest crediting rate that is 3% more than the annual change in the consumer price index. Refer to Note 13(c) for discussion of a class-action lawsuit filed against the Cash Balance Plan in 2008 and an agreement Alliant Energy reached with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. 401(k) Savings Plans - A significant number of Alliant Energy, IPL and WPL employees participate in defined contribution retirement plans (401(k) savings plans). Alliant Energy common stock represented 12.5% and 14.6% of total assets held in 401(k) savings plans at December 31, 2012 and 2011, respectively. Costs related to the 401(k) savings plans, which are partially based on the participants’ level of contribution, were as follows (in millions):
| Alliant Energy |  | IPL (a) |  | WPL (a)
| 2012 |  | 2011 |  | 2010 |  | 2012 |  |  | 2011 |  |  | 2010 |  |  | 2012 |  | 2011 |  | 2010
401(k) costs |  | $18.5 |  |  |  | $18.4 |  |  |  | $18.5 |  |  |  | $9.6 |  |  |  | $9.2 |  |  |  | $8.8 |  |  |  | $8.1 |  |  |  | $8.4 |  |  |  | $8.9 |
(a) | IPL’s and WPL’s amounts include allocated costs associated with Corporate Services employees.
(b) Equity-based Compensation Plans - In 2010, Alliant Energy’s shareowners approved the Alliant Energy 2010 Omnibus Incentive Plan (OIP), which permits the grant of stock options, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards and performance-based cash awards to key employees. At December 31, 2012, performance shares and restricted stock were outstanding and 4.2 million shares of Alliant Energy’s common stock remained available for grants under the OIP. Upon shareowner approval of the OIP, the Alliant Energy 2002 Equity Incentive Plan (EIP) terminated resulting in no new awards authorized to be granted under the EIP. All awards previously granted under the EIP that are still outstanding remain valid and continue to be subject to all of the terms and conditions of the EIP. At December 31, 2012, non-qualified stock options, restricted stock and performance shares were outstanding under the EIP and another predecessor plan under which new awards can no longer be granted. Alliant Energy satisfies payouts related to equity awards under the OIP and EIP through the issuance of new shares of its common stock. Alliant Energy also has the Alliant Energy Director Long Term Incentive Plan (DLIP), which permits the grant of long-term performance-based awards, including performance units and restricted cash awards to certain key employees. At December 31, 2012, performance units and performance contingent cash awards were outstanding under the DLIP. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash. A summary of compensation expense (allocated to IPL and WPL) and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Compensation expense |  | $6.9 |  |  |  | $10.1 |  |  |  | $7.5 |  |  |  | $3.6 |  |  |  | $5.5 |  |  |  | $4.0 |  |  |  | $3.0 |  |  |  | $4.1 |  |  |  | $3.0 |
Income tax benefits | 2.8 |  |  | 4.0 |  |  | 3.0 |  |  | 1.5 |  |  | 2.2 |  |  | 1.6 |  |  | 1.2 |  |  | 1.7 |  |  | 1.2 |
As of December 31, 2012, total unrecognized compensation cost related to share-based compensation awards was $6.1 million, which is expected to be recognized over a weighted average period of between 1 and 2 years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is primarily recorded in “Utility - Other operation and maintenance” in the Consolidated Statements of Income. Performance Shares and Units - Payouts of performance shares and units to key employees are contingent upon achievement over 3-year periods of specified performance criteria, which currently include metrics of total shareowner return relative to investor-owned utility peer groups. Payouts of nonvested performance shares and units issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of these performance shares and units to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Payouts of nonvested performance shares and units issued prior to 2012 are prorated at retirement, death, disability or involuntary termination without cause based on time worked during the full or entire performance period and achievement of the performance criteria. Participants’ nonvested performance shares and units are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested performance shares and units do not have non-forfeitable rights to dividends when dividends are paid to common shareowners. Alliant Energy assumes it will make future payouts of its performance shares and units in cash; therefore, performance shares and units are accounted for as liability awards. Performance Shares - Performance shares can be paid out in shares of Alliant Energy’s common stock, cash or a combination of cash and stock and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance shares activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares (a) |  | Shares (a) |  | Shares (a)
Nonvested shares, January 1 | 236,979 |  |  | 234,518 |  |  | 256,579 |
Granted | 45,612 |  |  | 64,217 |  |  | 72,487 |
Vested (b) | (111,980 | ) |  | (57,838 | ) |  | — |
Forfeited (c) | (25,334 | ) |  | (3,918 | ) |  | (94,548 | )
Nonvested shares, December 31 | 145,277 |  |  | 236,979 |  |  | 234,518 |
(a) | Share amounts represent the target number of performance shares. Each performance share’s value is based on the price of one share of Alliant Energy’s common stock at the end of the performance period. The actual number of shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares.
(b) | In 2012, 111,980 performance shares granted in 2009 vested at 162.5% of the target, resulting in payouts valued at $8.0 million, which consisted of a combination of cash and common stock (6,399 shares). In 2011, 57,838 performance shares granted in 2008 vested at 75% of the target, resulting in payouts valued at $1.6 million, which consisted of a combination of cash and common stock (1,387 shares).
(c) | In 2010, 57,100 performance shares granted in 2007 were forfeited without payout because the specified performance criteria for such shares were not met. The remaining forfeitures during 2012, 2011 and 2010 were primarily caused by retirements and voluntary terminations of participants.
Performance Units - Performance units must be paid out in cash and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance unit activity was as follows:
| 2012 |  | 2011 |  | 2010
| Units (a) |  | Units (a) |  | Units (a)
Nonvested units, January 1 | 42,996 |  |  | 23,128 |  |  | — |
Granted | 24,686 |  |  | 23,975 |  |  | 23,795 |
Forfeited | (2,713 | ) |  | (4,107 | ) |  | (667 | )
Nonvested units, December 31 | 64,969 |  |  | 42,996 |  |  | 23,128 |
(a) | Unit amounts represent the target number of performance units. Each performance unit’s value is based on the average price of one share of Alliant Energy’s common stock on the grant date of the award. The actual payout for performance units is dependent upon actual performance and may range from zero to 200% of the target number of units.
Fair Value of Awards - Information related to fair values of nonvested performance shares and units at December 31, 2012, by year of grant, were as follows:
| Performance Shares |  | Performance Units
| 2012 Grant |  | 2011 Grant |  | 2010 Grant |  | 2012 Grant |  | 2011 Grant |  | 2010 Grant
Nonvested awards | 45,612 |  |  | 45,235 |  |  | 54,430 |  |  | 23,969 |  |  | 21,095 |  |  | 19,905 |
Alliant Energy common stock closing price on December 31, 2012 |  | $43.91 |  |  |  | $43.91 |  |  |  | $43.91 |  |  |  |  |  |  |
Alliant Energy common stock average price on grant date |  |  |  |  |  |  |  | $43.05 |  |  |  | $38.75 |  |  |  | $32.56 |
Estimated payout percentage based on performance criteria | 89 | % |  | 107 | % |  | 198 | % |  | 89 | % |  | 107 | % |  | 198 | %
Fair values of each nonvested award |  | $39.08 |  |  |  | $46.98 |  |  |  | $86.72 |  |  |  | $38.31 |  |  |  | $41.46 |  |  |  | $64.30 |
At December 31, 2012, fair values of nonvested performance shares and units were calculated using a Monte Carlo simulation to determine the anticipated total shareowner returns of Alliant Energy and its investor-owned utility peer groups. Expected volatility was based on historical volatilities using daily stock prices over the past three years. Expected dividend yields were calculated based on the most recent quarterly dividend rates announced prior to the measurement date and stock prices at the measurement date. The risk-free interest rate was based on the three-year U.S. Treasury rate in effect as of the measurement date. Restricted Stock - Restricted stock consists of time-based and performance-contingent restricted stock. Time-based Restricted Stock - The current restriction period for outstanding time-based restricted stock is up to three years. Nonvested shares of time-based restricted stock generally become vested upon retirement. Compensation costs related to awards granted to retirement-eligible employees are generally expensed on the date of grant. Participants’ nonvested time-based restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Participants’ nonvested time-based restricted stock issued prior to 2012 is fully vested in the event of retirement, death, disability or involuntary termination without cause. The fair value of time-based restricted stock is based on the average market price at the grant date. A summary of the time-based restricted stock activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value
Nonvested shares, January 1 | 35,800 |  |  |  | $30.87 |  |  | 70,033 |  |  |  | $32.27 |  |  | 125,349 |  |  |  | $32.47 |
Granted | — |  |  | — |  |  | 5,000 |  |  | 39.86 |  |  | — |  |  | — |
Vested | (32,466 | ) |  | 29.95 |  |  | (38,633 | ) |  | 34.60 |  |  | (54,016 | ) |  | 32.72 |
Forfeited | — |  |  | — |  |  | (600 | ) |  | 29.41 |  |  | (1,300 | ) |  | 32.78 |
Nonvested shares, December 31 | 3,334 |  |  | 39.86 |  |  | 35,800 |  |  | 30.87 |  |  | 70,033 |  |  | 32.27 |
Performance-contingent Restricted Stock - Vesting of performance-contingent restricted stock grants are based on the achievement of certain performance targets (currently specified earnings growth). The performance metric for the 2012, 2011 and 2010 grants is consolidated net income growth. If performance targets are not met within the performance period, which currently ranges from two to four years, these restricted stock grants are forfeited. Payouts of nonvested performance-contingent restricted stock issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of this performance-contingent restricted stock to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Nonvested shares of performance-contingent restricted stock issued prior to 2012 are prorated at retirement based on time worked during the full or entire performance period and vest only if and when the performance criteria are met. Participants’ nonvested performance-contingent restricted stock is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. The fair value of performance-contingent restricted stock is based on the average market price at the grant date. A summary of the performance-contingent restricted stock activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value
Nonvested shares, January 1 | 301,738 |  |  |  | $32.60 |  |  | 296,190 |  |  |  | $32.32 |  |  | 226,007 |  |  |  | $32.25 |
Granted | 45,612 |  |  | 43.05 |  |  | 64,217 |  |  | 38.75 |  |  | 72,487 |  |  | 32.56 |
Vested (a) | (65,172 | ) |  | 32.56 |  |  | (53,274 | ) |  | 37.93 |  |  | — |  |  | — |
Forfeited (b) | (70,527 | ) |  | 39.93 |  |  | (5,395 | ) |  | 38.00 |  |  | (2,304 | ) |  | 32.56 |
Nonvested shares, December 31 | 211,651 |  |  | 32.42 |  |  | 301,738 |  |  | 32.60 |  |  | 296,190 |  |  | 32.32 |
(a) | In 2012 and 2011, 65,172 and 53,274 performance-contingent restricted shares granted in 2010 and 2007, respectively, vested because the specified performance criteria for such shares were met.
(b) | In 2012, 65,516 performance-contingent restricted shares granted in 2008 were forfeited because the specified performance criteria for such shares were not met. The remaining forfeitures during 2012, 2011 and 2010 were primarily caused by retirements and terminations of participants.
Non-qualified Stock Options - Options were granted at the market price of the shares on the date of grant, vested over three years and expire no later than 10 years after the grant date. Alliant Energy has not granted any options since 2004. A summary of the stock option activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Exercise Price |  | Shares |  | Weighted Average Exercise Price |  | Shares |  | Weighted Average Exercise Price
Outstanding, January 1 | 63,889 |  |  |  | $24.21 |  |  | 163,680 |  |  |  | $24.51 |  |  | 384,331 |  |  |  | $27.02 |
Exercised | (38,711 | ) |  | 24.41 |  |  | (99,791 | ) |  | 24.71 |  |  | (191,433 | ) |  | 28.93 |
Expired | — |  |  | — |  |  | — |  |  | — |  |  | (29,218 | ) |  | 28.59 |
Outstanding and exercisable, December 31 | 25,178 |  |  | 23.89 |  |  | 63,889 |  |  | 24.21 |  |  | 163,680 |  |  | 24.51 |
The weighted average remaining contractual term for options outstanding and exercisable at December 31, 2012 was 1 year. The aggregate intrinsic value of options outstanding and exercisable at December 31, 2012 was $0.5 million. Other information related to stock option activity was as follows (in millions):
| 2012 |  | 2011 |  | 2010
Cash received from stock options exercised |  | $0.9 |  |  |  | $2.5 |  |  |  | $5.5 |
Aggregate intrinsic value of stock options exercised | 0.8 |  |  | 1.6 |  |  | 1.1 |
Income tax benefit from the exercise of stock options | 0.3 |  |  | 0.7 |  |  | 0.4 |
Performance Contingent Cash Awards - Performance contingent cash award payouts to key employees are based on the achievement of certain performance targets (currently specified consolidated net income growth). If performance targets are not met within the performance period, which currently ranges from two to four years, there are no payouts for these awards. Payouts of nonvested awards issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of these 2012 awards to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Nonvested awards issued prior to 2012 are prorated at retirement based on time worked during the full or entire performance period and achievement of the performance criteria. Participants’ nonvested awards are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Each performance contingent cash award’s value is based on the price of one share of Alliant Energy’s common stock at the end of the performance period. Alliant Energy accounts for performance contingent cash awards as liability awards because payouts will be made in the form of cash. A summary of the performance contingent cash awards activity was as follows:
| 2012 |  | 2011 |  | 2010
| Awards |  | Awards |  | Awards
Nonvested awards, January 1 | 46,676 |  |  | 23,428 |  |  | — |
Granted | 36,936 |  |  | 23,975 |  |  | 23,795 |
Vested (a) | (21,605 | ) |  | — |  |  | — |
Forfeited | (2,368 | ) |  | (727 | ) |  | (367 | )
Nonvested awards, December 31 | 59,639 |  |  | 46,676 |  |  | 23,428 |
(a) | In 2012, 21,605 performance contingent cash awards granted in 2010 vested, resulting in cash payouts valued at $0.9 million.
(c) Deferred Compensation Plan (DCP) - Alliant Energy maintains a DCP under which key employees may defer up to 100% of base salary and performance-based compensation and directors may elect to defer all or part of their retainer and committee fees. Key employees who have made the maximum allowed contribution to the Alliant Energy 401(k) Savings Plan may receive an additional credit to the DCP. Key employees and directors may elect to have their deferrals credited to a company stock account, an interest account or equity accounts based on certain benchmark funds. Company Stock Accounts - The DCP does not permit diversification of deferrals credited to the company stock account and all distributions from participants’ company stock accounts are made in the form of shares of Alliant Energy common stock. The deferred compensation obligations for participants’ company stock accounts are recorded in “Additional paid-in capital” and the shares of Alliant Energy common stock held in a rabbi trust to satisfy this obligation are recorded in “Shares in deferred compensation trust” on Alliant Energy’s Consolidated Balance Sheets. At December 31, the carrying value of the deferred compensation obligation for the company stock accounts and the shares in the deferred compensation trust based on the historical value of the shares of Alliant Energy common stock contributed to the rabbi trust, and the fair market value of the shares held in the rabbi trust were as follows (in millions):
| 2012 |  | 2011
Carrying value |  | $7.3 |  |  |  | $8.3 |
Fair market value | 9.5 |  |  | 11.6 |
Interest and Equity Accounts - Distributions from participants’ interest and equity accounts are in the form of cash payments. The deferred compensation obligations for participants’ interest and equity accounts are recorded in “Pension and other benefit obligations” on Alliant Energy’s and IPL’s Consolidated Balance Sheets. At December 31, the carrying value of Alliant Energy’s and IPL’s deferred compensation obligations for participants’ interest and equity accounts was as follows (in millions):
| Alliant Energy |  | IPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Carrying value | $16.3 |  | $20.5 |  | $5.0 |  | $5.0
IPL [Member] |
Benefit Plans | BENEFIT PLANS (a) Pension and Other Postretirement Benefits Plans - Alliant Energy, IPL and WPL provide retirement benefits to substantially all of their employees through various qualified and non-qualified non-contributory defined benefit pension plans, and/or through defined contribution plans (including 401(k) savings plans). Alliant Energy’s, IPL’s and WPL’s qualified and non-qualified non-contributory defined benefit pension plans are currently closed to new hires. Benefits of the non-contributory defined benefit pension plans are based on the plan participant’s years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant’s years of service, age, compensation and contributions. Alliant Energy, IPL and WPL also provide certain defined benefit postretirement health care and life benefits to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory. Assumptions - The assumptions for defined benefit pension and other postretirement benefits plans at the measurement date of December 31 were as follows (Not Applicable (N/A)):
Alliant Energy | Defined Benefit Pension Plans |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.11% |  | 4.86% |  | 5.56% |  | 3.82% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.86% |  | 5.56% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.50% |  | 7.00% |  | 6.90%
Rate of compensation increase | 3.50 | % | - | 4.50% |  | 3.50 | % | - | 4.50% |  | 3.50 | % | - | 4.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
IPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.20% |  | 4.95% |  | 5.70% |  | 3.76% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.95% |  | 5.70% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.40% |  | 7.30% |  | 7.10%
Rate of compensation increase | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
WPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.20% |  | 4.95% |  | 5.70% |  | 3.81% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.95% |  | 5.70% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.00% |  | 6.30% |  | 6.30%
Rate of compensation increase | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
Expected rate of return on plan assets - The expected rate of return on plan assets is determined by analysis of projected asset class returns based on the target asset class allocations. Alliant Energy, IPL and WPL use a forward-looking building blocks approach and also review historical returns, survey information and capital market information to support the expected rate of return on plan assets assumption. Refer to “Investment Policy and Strategy for Plan Assets” below for additional information related to Alliant Energy’s, IPL’s and WPL’s investment policy and strategy and mix of assets for the pension and other postretirement benefits plans. Medical cost trend on covered charges - The assumed medical trend rates are critical assumptions in determining the service and interest cost and accumulated postretirement benefit obligation related to postretirement benefits costs. A 1% change in the medical trend rates for 2012, holding all other assumptions constant, would have the following effects (in millions):
| Alliant Energy |  | IPL |  | WPL
| 1% Increase |  | 1% Decrease |  | 1% Increase |  | 1% Decrease |  | 1% Increase |  | 1% Decrease
Effect on total of service and interest cost components |  | $0.4 |  |  |  | ($0.4 | ) |  |  | $0.2 |  |  |  | ($0.2 | ) |  |  | $0.2 |  |  |  | ($0.2 | )
Effect on postretirement benefit obligation | 2.6 |  |  | (2.4 | ) |  | 1.2 |  |  | (1.1 | ) |  | 1.2 |  |  | (1.2 | )
Net Periodic Benefit Costs (Credits) - The components of net periodic benefit costs (credits) for Alliant Energy’s, IPL’s and WPL’s sponsored defined benefit pension and other postretirement benefits plans, and defined benefit pension plans amounts directly assigned to IPL and WPL, are included in the tables below (in millions). In the “IPL” and “WPL” tables below, the qualified defined benefit pension plans costs represent only those respective costs for IPL’s and WPL’s bargaining unit employees covered under the plans that are sponsored by IPL and WPL, respectively. Also in the “IPL” and “WPL” tables below, the other postretirement benefits plans costs (credits) represent costs (credits) for all IPL and WPL employees, respectively. The “Directly assigned defined benefit pension plans” tables below include amounts directly assigned to each of IPL and WPL related to IPL’s and WPL’s current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Alliant Energy | Defined Benefit Pension Plans |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $13.5 |  |  |  | $11.4 |  |  |  | $11.9 |  |  |  | $6.9 |  |  |  | $7.0 |  |  |  | $9.3 |
Interest cost | 51.6 |  |  | 52.0 |  |  | 52.3 |  |  | 10.2 |  |  | 12.3 |  |  | 14.9 |
Expected return on plan assets (b) | (68.8 | ) |  | (63.8 | ) |  | (62.1 | ) |  | (7.5 | ) |  | (7.9 | ) |  | (7.7 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Transition obligation | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |
Prior service cost (credit) | 0.3 |  |  | 0.7 |  |  | 0.9 |  |  | (12.0 | ) |  | (10.0 | ) |  | (2.4 | )
Actuarial loss | 33.3 |  |  | 21.1 |  |  | 23.8 |  |  | 6.3 |  |  | 5.3 |  |  | 7.4 |
Additional benefit costs (d) | 0.1 |  |  | 10.2 |  |  | — |  |  | — |  |  | — |  |  | — |
Settlement losses (e) | 5.4 |  |  | 1.1 |  |  | 1.4 |  |  | — |  |  | — |  |  | — |
|  | $35.4 |  |  |  | $32.7 |  |  |  | $28.2 |  |  |  | $3.9 |  |  |  | $6.7 |  |  |  | $21.6 |
IPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $7.5 |  |  |  | $6.1 |  |  |  | $6.2 |  |  |  | $3.0 |  |  |  | $2.6 |  |  |  | $3.4 |
Interest cost | 17.1 |  |  | 16.7 |  |  | 16.5 |  |  | 4.4 |  |  | 5.5 |  |  | 6.8 |
Expected return on plan assets (b) | (23.0 | ) |  | (20.0 | ) |  | (19.5 | ) |  | (5.1 | ) |  | (5.4 | ) |  | (5.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Transition obligation | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |
Prior service cost (credit) | 0.4 |  |  | 0.5 |  |  | 0.6 |  |  | (6.3 | ) |  | (5.0 | ) |  | (1.1 | )
Actuarial loss | 10.2 |  |  | 5.7 |  |  | 7.2 |  |  | 3.5 |  |  | 2.9 |  |  | 4.0 |
|  | $12.2 |  |  |  | $9.0 |  |  |  | $11.0 |  |  |  | ($0.5 | ) |  |  | $0.6 |  |  |  | $7.9 |
WPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $5.2 |  |  |  | $4.5 |  |  |  | $4.9 |  |  |  | $2.7 |  |  |  | $2.9 |  |  |  | $3.6 |
Interest cost | 16.4 |  |  | 16.1 |  |  | 15.7 |  |  | 4.1 |  |  | 4.9 |  |  | 5.5 |
Expected return on plan assets (b) | (22.3 | ) |  | (20.0 | ) |  | (19.1 | ) |  | (1.3 | ) |  | (1.3 | ) |  | (1.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Prior service cost (credit) | 0.5 |  |  | 0.5 |  |  | 0.5 |  |  | (3.9 | ) |  | (3.4 | ) |  | (0.7 | )
Actuarial loss | 12.1 |  |  | 7.1 |  |  | 8.5 |  |  | 2.3 |  |  | 2.1 |  |  | 2.5 |
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
|  | $12.0 |  |  |  | $8.2 |  |  |  | $10.5 |  |  |  | $3.9 |  |  |  | $5.2 |  |  |  | $9.6 |
Directly assigned defined benefit pension plans | IPL |  | WPL
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Interest cost |  | $7.0 |  |  |  | $7.3 |  |  |  | $7.8 |  |  |  | $5.2 |  |  |  | $5.5 |  |  |  | $5.6 |
Expected return on plan assets (b) | (9.6 | ) |  | (9.7 | ) |  | (9.7 | ) |  | (7.3 | ) |  | (7.3 | ) |  | (7.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Prior service credit | (0.2 | ) |  | (0.2 | ) |  | (0.3 | ) |  | (0.1 | ) |  | (0.2 | ) |  | (0.2 | )
Actuarial loss | 3.9 |  |  | 3.0 |  |  | 2.9 |  |  | 3.6 |  |  | 3.0 |  |  | 2.8 |
Additional benefit costs (d) | — |  |  | 2.8 |  |  | — |  |  | — |  |  | 0.7 |  |  | — |
|  | $1.1 |  |  |  | $3.2 |  |  |  | $0.7 |  |  |  | $1.4 |  |  |  | $1.7 |  |  |  | $0.9 |
(a) | In 2011, Alliant Energy, IPL and WPL amended their defined benefit postretirement health care plans resulting in a revision to the method and level of coverage provided for participants more than 65 years of age. This amendment was determined to be a significant event, which required Alliant Energy, IPL and WPL to remeasure their defined benefit postretirement health care plans in 2011. The amendment resulted in a decrease in Alliant Energy’s, IPL’s and WPL’s postretirement benefit obligations of $55 million, $30 million and $16 million, respectively, in 2011 with the impact of the remeasurement on net periodic benefit costs being recognized prospectively from the remeasurement date. The impact of the remeasurement decreased Alliant Energy’s, IPL’s and WPL’s net periodic benefit costs by $11.3 million, $7.2 million, and $3.8 million in 2011, respectively. The discount rate used for the remeasurement was 5.20%. All other assumptions used for the remeasurement were consistent with the measurement assumptions used at December 31, 2010.
(b) | The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.
(c) | Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan (Cash Balance Plan) where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits. Unrecognized prior service costs (credits) for the postretirement benefits plans are amortized over the average future service period to full eligibility of the participants of each plan.
(d) | Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. The agreement with the IRS required Alliant Energy to amend the Cash Balance Plan, which was completed in 2011 resulting in aggregate additional benefits of $10.2 million paid by Alliant Energy to certain former participants in the Cash Balance Plan in 2011. Alliant Energy recognized $10.2 million of additional benefits costs in 2011 related to these benefits. IPL recognized $6.3 million ($2.8 million directly assigned and $3.5 million allocated by Corporate Services) and WPL recognized $3.4 million ($0.7 million directly assigned and $2.7 million allocated by Corporate Services) of additional benefits costs in 2011 related to these benefits. Refer to Note 13(c) for additional information regarding the Cash Balance Plan.
(e) | Settlement losses related to payments made to retired executives of Alliant Energy.
Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs associated with Corporate Services employees. The following table includes the allocated qualified and non-qualified pension and other postretirement benefits costs associated with Corporate Services employees providing services to IPL and WPL (in millions):
| Pension Benefits Costs (a) |  | Other Postretirement Benefits Costs
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
IPL |  | $4.9 |  |  |  | $5.8 |  |  |  | $2.9 |  |  |  | $0.1 |  |  |  | $0.3 |  |  |  | $2.0 |
WPL | 3.6 |  |  | 4.2 |  |  | 1.9 |  |  | 0.1 |  |  | 0.2 |  |  | 1.3 |
(a) | Includes settlement losses related to payments made to retired executives of Alliant Energy in 2012. In 2011, additional qualified pension benefits costs resulting from the 2011 amendment to the Cash Balance Plan allocated to IPL and WPL by Corporate Services were $3.5 million and $2.7 million, respectively.
The estimated amortization from “Regulatory assets” and “Regulatory liabilities” on the Consolidated Balance Sheets and AOCL on Alliant Energy’s Consolidated Balance Sheet into net periodic benefit cost in 2013 is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
|  |  | Other |  | Qualified |  | Other |  | Qualified |  | Other
| Defined Benefit |  | Postretirement |  | Defined Benefit |  | Postretirement |  | Defined Benefit |  | Postretirement
| Pension Plans |  | Benefits Plans |  | Pension Plan |  | Benefits Plans |  | Pension Plan |  | Benefits Plans
Actuarial loss |  | $36.2 |  |  |  | $4.9 |  |  |  | $10.9 |  |  |  | $2.7 |  |  |  | $13.2 |  |  |  | $1.9 |
Prior service cost (credit) | 0.2 |  |  | (11.9 | ) |  | 0.4 |  |  | (6.3 | ) |  | 0.5 |  |  | (3.9 | )
|  | $36.4 |  |  |  | ($7.0 | ) |  |  | $11.3 |  |  |  | ($3.6 | ) |  |  | $13.7 |  |  |  | ($2.0 | )
Directly assigned defined benefit pension plans | IPL |  | WPL
Actuarial loss |  | $4.2 |  |  |  | $3.9 |
Prior service credit | (0.2 | ) |  | (0.2 | )
|  | $4.0 |  |  |  | $3.7 |
In addition to the estimated amortizations from “Regulatory assets” and “Regulatory liabilities” in the above tables for IPL and WPL, $1.3 million and $0.9 million, respectively, of amortizations are expected in 2013 from “Regulatory assets” and “Regulatory liabilities” associated with Corporate Services employees participating in other Alliant Energy sponsored plans allocated to IPL and WPL. Alliant Energy’s, IPL’s and WPL’s net periodic benefit costs are primarily included in “Utility - Other operation and maintenance” in the Consolidated Statements of Income. Benefit Plan Assets and Obligations - A reconciliation of the funded status of Alliant Energy’s qualified and non-qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on Alliant Energy’s Consolidated Balance Sheets at December 31 was as follows (in millions):
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $1,081.4 |  |  |  | $953.0 |  |  |  | $224.2 |  |  |  | $274.9 |
Service cost | 13.5 |  |  | 11.4 |  |  | 6.9 |  |  | 7.0 |
Interest cost | 51.6 |  |  | 52.0 |  |  | 10.2 |  |  | 12.3 |
Plan participants’ contributions | — |  |  | — |  |  | 2.7 |  |  | 6.4 |
Plan amendments (a) | — |  |  | 10.2 |  |  | — |  |  | (56.6 | )
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |
Actuarial (gain) loss | 135.4 |  |  | 126.2 |  |  | (1.6 | ) |  | (0.8 | )
Early Retiree Reinsurance Program (ERRP) proceeds | — |  |  | — |  |  | — |  |  | 0.6 |
Gross benefits paid | (74.5 | ) |  | (71.4 | ) |  | (19.2 | ) |  | (20.8 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 1.2 |
Net projected benefit obligation at December 31 | 1,207.5 |  |  | 1,081.4 |  |  | 223.2 |  |  | 224.2 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 897.4 |  |  | 823.0 |  |  | 120.4 |  |  | 122.7 |
Actual return on plan assets | 126.9 |  |  | 28.9 |  |  | 14.3 |  |  | 2.6 |
Employer contributions | 15.8 |  |  | 116.9 |  |  | 4.9 |  |  | 9.5 |
Plan participants’ contributions | — |  |  | — |  |  | 2.7 |  |  | 6.4 |
Gross benefits paid | (74.5 | ) |  | (71.4 | ) |  | (19.2 | ) |  | (20.8 | )
Fair value of plan assets at December 31 | 965.6 |  |  | 897.4 |  |  | 123.1 |  |  | 120.4 |
Under funded status at December 31 |  | ($241.9 | ) |  |  | ($184.0 | ) |  |  | ($100.1 | ) |  |  | ($103.8 | )
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Non-current assets |  | $— |  |  |  | $— |  |  |  | $3.5 |  |  |  | $1.3 |
Other current liabilities | (2.4 | ) |  | (4.6 | ) |  | (2.8 | ) |  | — |
Pension and other benefit obligations | (239.5 | ) |  | (179.4 | ) |  | (100.8 | ) |  | (105.1 | )
Net amount recognized at December 31 |  | ($241.9 | ) |  |  | ($184.0 | ) |  |  | ($100.1 | ) |  |  | ($103.8 | )
Amounts recognized in Regulatory Assets, Regulatory Liabilities and AOCL consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $533.4 |  |  |  | $494.8 |  |  |  | $62.1 |  |  |  | $76.7 |
Prior service credit | (7.2 | ) |  | (6.9 | ) |  | (40.5 | ) |  | (52.5 | )
|  | $526.2 |  |  |  | $487.9 |  |  |  | $21.6 |  |  |  | $24.2 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) and Alliant Energy’s Consolidated Statements of Common Equity for amounts recognized in “Regulatory assets” and “AOCL,” respectively, on Alliant Energy’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $2.7 million and $3.3 million, respectively, of regulatory liabilities were recognized related to Alliant Energy’s other postretirement benefits plans.
A reconciliation of the funded status of IPL’s sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on IPL’s Consolidated Balance Sheets, at December 31 was as follows (in millions):
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $344.5 |  |  |  | $293.8 |  |  |  | $97.5 |  |  |  | $128.5 |
Service cost | 7.5 |  |  | 6.1 |  |  | 3.0 |  |  | 2.6 |
Interest cost | 17.1 |  |  | 16.7 |  |  | 4.4 |  |  | 5.5 |
Plan participants’ contributions | — |  |  | — |  |  | 0.9 |  |  | 2.0 |
Plan amendments (a) | — |  |  | — |  |  | — |  |  | (30.1 | )
Actuarial (gain) loss | 38.2 |  |  | 45.2 |  |  | (1.4 | ) |  | (2.7 | )
ERRP proceeds | — |  |  | — |  |  | — |  |  | 0.2 |
Gross benefits paid | (18.9 | ) |  | (17.3 | ) |  | (8.4 | ) |  | (9.1 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 0.6 |
Net projected benefit obligation at December 31 | 388.4 |  |  | 344.5 |  |  | 96.0 |  |  | 97.5 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 298.7 |  |  | 256.9 |  |  | 74.7 |  |  | 77.5 |
Actual return on plan assets | 42.5 |  |  | 9.1 |  |  | 9.4 |  |  | 1.4 |
Employer contributions | — |  |  | 50.0 |  |  | 2.2 |  |  | 2.9 |
Plan participants’ contributions | — |  |  | — |  |  | 0.9 |  |  | 2.0 |
Gross benefits paid | (18.9 | ) |  | (17.3 | ) |  | (8.4 | ) |  | (9.1 | )
Fair value of plan assets at December 31 | 322.3 |  |  | 298.7 |  |  | 78.8 |  |  | 74.7 |
Under funded status at December 31 |  | ($66.1 | ) |  |  | ($45.8 | ) |  |  | ($17.2 | ) |  |  | ($22.8 | )
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Pension and other benefit obligations |  | ($66.1 | ) |  |  | ($45.8 | ) |  |  | ($17.2 | ) |  |  | ($22.8 | )
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $149.7 |  |  |  | $141.1 |  |  |  | $32.0 |  |  |  | $41.0 |
Prior service cost (credit) | 0.7 |  |  | 1.1 |  |  | (21.3 | ) |  | (27.6 | )
|  | $150.4 |  |  |  | $142.2 |  |  |  | $10.7 |  |  |  | $13.4 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on IPL’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $1.4 million and $2.8 million, respectively, of regulatory liabilities were recognized related to IPL’s other postretirement benefits plans.
A reconciliation of the funded status of WPL’s sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on WPL’s Consolidated Balance Sheets, at December 31 was as follows (in millions):
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $332.5 |  |  |  | $283.3 |  |  |  | $89.6 |  |  |  | $103.3 |
Service cost | 5.2 |  |  | 4.5 |  |  | 2.7 |  |  | 2.9 |
Interest cost | 16.4 |  |  | 16.1 |  |  | 4.1 |  |  | 4.9 |
Plan participants’ contributions | — |  |  | — |  |  | 1.2 |  |  | 3.3 |
Plan amendments (a) | — |  |  | — |  |  | — |  |  | (18.2 | )
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |
Actuarial loss | 43.4 |  |  | 43.3 |  |  | 0.3 |  |  | 2.3 |
ERRP proceeds | — |  |  | — |  |  | — |  |  | 0.2 |
Gross benefits paid | (17.4 | ) |  | (14.7 | ) |  | (8.8 | ) |  | (9.6 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 0.5 |
Net projected benefit obligation at December 31 | 380.2 |  |  | 332.5 |  |  | 89.1 |  |  | 89.6 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 289.6 |  |  | 255.2 |  |  | 25.1 |  |  | 25.0 |
Actual return on plan assets | 41.0 |  |  | 9.1 |  |  | 2.5 |  |  | 0.9 |
Employer contributions | — |  |  | 40.0 |  |  | 2.3 |  |  | 5.5 |
Plan participants’ contributions | — |  |  | — |  |  | 1.2 |  |  | 3.3 |
Gross benefits paid | (17.4 | ) |  | (14.7 | ) |  | (8.8 | ) |  | (9.6 | )
Fair value of plan assets at December 31 | 313.2 |  |  | 289.6 |  |  | 22.3 |  |  | 25.1 |
Under funded status at December 31 |  | ($67.0 | ) |  |  | ($42.9 | ) |  |  | ($66.8 | ) |  |  | ($64.5 | )
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Non-current assets |  | $— |  |  |  | $— |  |  |  | $3.5 |  |  |  | $1.3 |
Other current liabilities | — |  |  | — |  |  | (2.8 | ) |  | — |
Pension and other benefit obligations | (67.0 | ) |  | (42.9 | ) |  | (67.5 | ) |  | (65.8 | )
Net amount recognized at December 31 |  | ($67.0 | ) |  |  | ($42.9 | ) |  |  | ($66.8 | ) |  |  | ($64.5 | )
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $155.3 |  |  |  | $142.7 |  |  |  | $24.3 |  |  |  | $27.8 |
Prior service cost (credit) | 1.9 |  |  | 2.4 |  |  | (13.4 | ) |  | (17.3 | )
|  | $157.2 |  |  |  | $145.1 |  |  |  | $10.9 |  |  |  | $10.5 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on WPL’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $0.2 million and $0, respectively, of regulatory liabilities were recognized related to WPL’s other postretirement benefits plans.
Included in the following tables are accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and other postretirement benefits plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the December 31 measurement date (Not Applicable (N/A); in millions):
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $1,155.5 |  |  |  | $1,029.4 |  |  |  | $223.2 |  |  |  | $224.2 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 1,155.5 |  |  | 1,029.4 |  |  | 223.2 |  |  | 224.2 |
Fair value of plan assets | 965.6 |  |  | 897.4 |  |  | 123.1 |  |  | 120.4 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 1,207.5 |  |  | 1,081.4 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 965.6 |  |  | 897.4 |  |  | N/A |  |  | N/A |
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $359.6 |  |  |  | $314.6 |  |  |  | $96.0 |  |  |  | $97.5 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 359.6 |  |  | 314.6 |  |  | 96.0 |  |  | 97.5 |
Fair value of plan assets | 322.3 |  |  | 298.7 |  |  | 78.8 |  |  | 74.7 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 388.4 |  |  | 344.5 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 322.3 |  |  | 298.7 |  |  | N/A |  |  | N/A |
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $363.7 |  |  |  | $314.7 |  |  |  | $89.1 |  |  |  | $89.6 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 363.7 |  |  | 314.7 |  |  | 89.1 |  |  | 89.6 |
Fair value of plan assets | 313.2 |  |  | 289.6 |  |  | 22.3 |  |  | 25.1 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 380.2 |  |  | 332.5 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 313.2 |  |  | 289.6 |  |  | N/A |  |  | N/A |
The “Directly assigned defined benefit pension plans” table below includes amounts directly assigned to each of IPL and WPL related to their current and former non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. A reconciliation of the funded status of the directly assigned qualified and non-qualified defined benefit pension plans to the amounts recognized on IPL’s and WPL’s Consolidated Balance Sheets at December 31 was as follows (in millions):
Directly assigned defined benefit pension plans | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $155.4 |  |  |  | $144.4 |  |  |  | $115.2 |  |  |  | $107.4 |
Interest cost | 7.0 |  |  | 7.3 |  |  | 5.2 |  |  | 5.5 |
Plan amendments | — |  |  | 2.8 |  |  | — |  |  | 0.7 |
Actuarial loss | 17.9 |  |  | 13.2 |  |  | 14.5 |  |  | 10.3 |
Gross benefits paid | (9.5 | ) |  | (12.3 | ) |  | (8.4 | ) |  | (8.7 | )
Net projected benefit obligation at December 31 | 170.8 |  |  | 155.4 |  |  | 126.5 |  |  | 115.2 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 127.4 |  |  | 127.6 |  |  | 97.0 |  |  | 95.6 |
Actual return on plan assets | 17.9 |  |  | 4.2 |  |  | 13.5 |  |  | 3.2 |
Employer contributions | 0.7 |  |  | 7.9 |  |  | 0.1 |  |  | 6.9 |
Gross benefits paid | (9.5 | ) |  | (12.3 | ) |  | (8.4 | ) |  | (8.7 | )
Fair value of plan assets at December 31 | 136.5 |  |  | 127.4 |  |  | 102.2 |  |  | 97.0 |
Under funded status at December 31 |  | ($34.3 | ) |  |  | ($28.0 | ) |  |  | ($24.3 | ) |  |  | ($18.2 | )
Directly assigned defined benefit pension plans | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Other current liabilities |  | ($0.8 | ) |  |  | ($0.8 | ) |  |  | ($0.2 | ) |  |  | ($0.2 | )
Pension and other benefit obligations | (33.5 | ) |  | (27.2 | ) |  | (24.1 | ) |  | (18.0 | )
Net amount recognized at December 31 |  | ($34.3 | ) |  |  | ($28.0 | ) |  |  | ($24.3 | ) |  |  | ($18.2 | )
Amounts recognized in Regulatory Assets (a): |  |  |  |  |  |  |
Net actuarial loss |  | $81.9 |  |  |  | $76.2 |  |  |  | $78.4 |  |  |  | $73.7 |
Prior service credit | (3.2 | ) |  | (3.4 | ) |  | (2.3 | ) |  | (2.4 | )
|  | $78.7 |  |  |  | $72.8 |  |  |  | $76.1 |  |  |  | $71.3 |
Accumulated benefit obligations |  | $170.8 |  |  |  | $155.4 |  |  |  | $126.5 |  |  |  | $115.2 |
(a) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on IPL’s and WPL’s Consolidated Balance Sheets.
In addition to the amounts recognized in “Regulatory assets and regulatory liabilities” in the above tables for IPL and WPL, “Regulatory assets” and “Regulatory liabilities” were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at December 31 as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Regulatory assets |  | $38.1 |  |  |  | $33.7 |  |  |  | $25.5 |  |  |  | $22.3 |
Regulatory liabilities | 0.6 |  |  | 0.3 |  |  | 0.4 |  |  | 0.2 |
Estimated Future Employer Contributions and Benefit Payments - Alliant Energy, IPL and WPL estimate that funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans, and the directly assigned qualified and non-qualified defined benefit pension plans amounts, during 2013 will be as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Qualified defined benefit pension plans |  | $— |  |  |  | $— |  |  |  | $— |
Non-qualified defined benefit pension plans (a) | 2.4 |  |  | N/A |  |  | N/A |
Directly assigned defined benefit pension plans (b) | N/A |  |  | 0.8 |  |  | 0.2 |
Other postretirement benefits plans | 3.0 |  |  | — |  |  | 3.0 |
(a) | Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans.
(b) | Amounts directly assigned to IPL and WPL for non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Expected benefit payments, and the directly assigned qualified and non-qualified defined benefit pension benefits amounts, which reflect expected future service, as appropriate, are as follows (in millions):
Alliant Energy | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified and non-qualified defined benefit pension benefits |  | $61.9 |  |  |  | $64.7 |  |  |  | $68.5 |  |  |  | $66.6 |  |  |  | $69.2 |  |  |  | $374.1 |
Other postretirement benefits | 16.6 |  |  | 16.2 |  |  | 16.3 |  |  | 16.4 |  |  | 16.6 |  |  | 84.2 |
|  | $78.5 |  |  |  | $80.9 |  |  |  | $84.8 |  |  |  | $83.0 |  |  |  | $85.8 |  |  |  | $458.3 |
IPL | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified defined benefit pension benefits |  | $15.9 |  |  |  | $16.9 |  |  |  | $17.9 |  |  |  | $18.9 |  |  |  | $20.0 |  |  |  | $116.0 |
Directly assigned defined benefit pension benefits | 12.6 |  |  | 13.4 |  |  | 14.1 |  |  | 12.1 |  |  | 13.5 |  |  | 60.2 |
Other postretirement benefits | 8.0 |  |  | 7.3 |  |  | 7.2 |  |  | 7.1 |  |  | 7.2 |  |  | 35.9 |
|  | $36.5 |  |  |  | $37.6 |  |  |  | $39.2 |  |  |  | $38.1 |  |  |  | $40.7 |  |  |  | $212.1 |
WPL | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified defined benefit pension benefits |  | $14.4 |  |  |  | $15.2 |  |  |  | $16.1 |  |  |  | $17.0 |  |  |  | $18.0 |  |  |  | $108.7 |
Directly assigned defined benefit pension benefits | 10.5 |  |  | 10.2 |  |  | 11.4 |  |  | 9.8 |  |  | 9.5 |  |  | 43.0 |
Other postretirement benefits | 6.3 |  |  | 6.5 |  |  | 6.7 |  |  | 6.7 |  |  | 6.8 |  |  | 34.3 |
|  | $31.2 |  |  |  | $31.9 |  |  |  | $34.2 |  |  |  | $33.5 |  |  |  | $34.3 |  |  |  | $186.0 |
Investment Policy and Strategy for Plan Assets - Alliant Energy’s, IPL’s and WPL’s investment policies and their strategies employed with respect to assets of defined benefit pension and other postretirement benefits plans are to combine both preservation of principal and prudent and reasonable risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. It is recognized that risk and volatility are present with all types of investments. However, risk is mitigated at the total fund level through diversification by asset class including both U.S. and international equity exposure, the number of individual investments, and sector and industry limits. Defined Benefit Pension Plans Assets - For assets of defined benefit pension plans, the mix among asset classes is controlled by long-term asset allocation targets. Historical performance results and future expectations suggest that equity securities will provide higher total investment returns than debt securities over a long-term investment horizon. Consistent with the goals of meeting obligations to plan participants and minimizing benefit costs over the long-term, the defined benefit pension plans have a long-term investment posture more heavily weighted towards equity holdings. The asset allocation is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. Alliant Energy, IPL and WPL also use an overlay management service to help maintain target allocations and liquidity needs. The overlay manager is authorized to use derivative financial instruments to facilitate this service. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, margin trading, oil and gas limited partnerships and securities of the managers’ firms or affiliate firms. If the investment vehicle is a commingled account or mutual fund, it is not possible to place restrictions on any aspect of fund management. At December 31, 2012, the current target ranges and actual allocations for Alliant Energy’s, IPL’s and WPL’s defined benefit pension plan assets were as follows:
| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | — | % | - | 5% |  | 4%
Equity securities: |  |  |  |  |
U.S. large cap core | 10 | % | - | 20% |  | 13%
U.S. large cap value | 6 | % | - | 16% |  | 11%
U.S. large cap growth | 6 | % | - | 16% |  | 11%
U.S. small cap value | — | % | - | 6% |  | 3%
U.S. small cap growth | — | % | - | 6% |  | 3%
International - developed markets | 11 | % | - | 23% |  | 16%
International - emerging markets | — | % | - | 8% |  | 4%
Global asset allocation securities | 5 | % | - | 15% |  | 10%
Fixed income securities | 15 | % | - | 35% |  | 25%
Other Postretirement Benefits Plans Assets - Other postretirement benefits plans assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in Voluntary Employees’ Beneficiary Association (VEBA) trusts. The investment policy and strategy of the 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. For VEBA trusts with assets greater than $5 million, the mix among asset classes is controlled by long-term allocation targets. The asset allocation is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, margin trading, oil and gas limited partnerships and securities of the managers’ firms or affiliate firms. If the investment vehicle is a commingled account or mutual fund, it is not possible to place restrictions on any aspect of fund management. At December 31, 2012, the current target ranges and actual allocations for Alliant Energy’s, IPL’s and WPL’s VEBA trusts with assets greater than $5 million were as follows:
| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | — | % | - | 5% |  | 2%
Equity securities: |  |  |  |  |
Domestic | 25 | % | - | 45% |  | 34%
International | 10 | % | - | 20% |  | 15%
Global asset allocation securities | 20 | % | - | 40% |  | 29%
Fixed income securities | 10 | % | - | 30% |  | 20%
Securities Lending Program - Alliant Energy, IPL and WPL have a securities lending program with a third-party agent that allows the agent to lend certain securities from their defined benefit pension and other postretirement benefits plans to selected entities against receipt of collateral (in the form of cash, government and agency securities or letters of credit) as provided for and determined in accordance with its securities lending agency agreement. Initial collateral levels are no less than 100% of the market value of loans to non-affiliated borrowers of U.S. government securities; 102% of the market value of loans to affiliated borrowers of U.S. government securities; 102% of the market value of loans on U.S. corporate bonds and U.S. equity securities; 105% of the market value of loans on non-U.S. securities; and 102% of the market value of loans on all other securities. Refer to “Fair Value Measurements” below for details of fair value of invested collateral and amounts due to borrowers for the securities lending program. Fair Value Measurements - The following tables report a framework for measuring fair value. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows: Level 1 - Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. Alliant Energy’s, IPL’s and WPL’s investments in equity and fixed income securities held in registered investment companies and directly held equity securities are valued at the closing price reported in the active market in which the securities are traded. Level 2 - Pricing inputs are quoted prices for similar asset or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Alliant Energy’s, IPL’s and WPL’s investments in corporate bonds and government and agency obligations are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Alliant Energy’s, IPL’s and WPL’s investments in equity and fixed income securities in common/collective trusts are valued at the net asset value of shares held by the plans, which is based on the fair market value of the underlying investments in equity and fixed income securities of the common/collective trusts. Level 2 plan assets also consist of asset backed securities within their securities lending invested collateral. Level 3 - Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. Alliant Energy’s, IPL’s and WPL’s Level 3 plan assets include certain asset backed securities and corporate bonds within their securities lending invested collateral. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while Alliant Energy, IPL and WPL believe their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. At December 31, the fair values of Alliant Energy’s qualified and non-qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):
Alliant Energy | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $43.9 |  |  |  | $— |  |  |  | $43.9 |  |  |  | $— |  |  |  | $117.5 |  |  |  | $117.5 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 129.0 |  |  | 129.0 |  |  | — |  |  | — |  |  | 110.7 |  |  | 110.7 |  |  | — |  |  | — |
U.S. large cap value | 107.9 |  |  | — |  |  | 107.9 |  |  | — |  |  | 91.6 |  |  | — |  |  | 91.6 |  |  | — |
U.S. large cap growth | 105.8 |  |  | — |  |  | 105.8 |  |  | — |  |  | 91.5 |  |  | — |  |  | 91.5 |  |  | — |
U.S. small cap value | 30.4 |  |  | — |  |  | 30.4 |  |  | — |  |  | 25.7 |  |  | — |  |  | 25.7 |  |  | — |
U.S. small cap growth | 25.0 |  |  | 25.0 |  |  | — |  |  | — |  |  | 21.7 |  |  | 21.7 |  |  | — |  |  | — |
International - developed markets | 153.7 |  |  | 80.3 |  |  | 73.4 |  |  | — |  |  | 126.4 |  |  | 65.4 |  |  | 61.0 |  |  | — |
International - emerging markets | 38.5 |  |  | 38.5 |  |  | — |  |  | — |  |  | 30.4 |  |  | 30.4 |  |  | — |  |  | — |
Global asset allocation securities | 94.5 |  |  | 56.3 |  |  | 38.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 30.7 |  |  | — |  |  | 30.7 |  |  | — |  |  | 57.1 |  |  | — |  |  | 57.1 |  |  | — |
Government and agency obligations | 49.2 |  |  | — |  |  | 49.2 |  |  | — |  |  | 87.8 |  |  | — |  |  | 87.8 |  |  | — |
Fixed income funds | 162.6 |  |  | 0.2 |  |  | 162.4 |  |  | — |  |  | 146.7 |  |  | 0.2 |  |  | 146.5 |  |  | — |
Securities lending invested collateral | 4.4 |  |  | — |  |  | 2.9 |  |  | 1.5 |  |  | 9.3 |  |  | 4.7 |  |  | 2.8 |  |  | 1.8 |
| 975.6 |  |  |  | $329.3 |  |  |  | $644.8 |  |  |  | $1.5 |  |  | 916.4 |  |  |  | $350.6 |  |  |  | $564.0 |  |  |  | $1.8 |
Accrued investment income | 0.6 |  |  |  |  |  |  |  |  | 1.0 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (1.5 | ) |  |  |  |  |  |  |  | (4.7 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (9.1 | ) |  |  |  |  |  |  |  | (15.3 | ) |  |  |  |  |  |
Total pension plan assets |  | $965.6 |  |  |  |  |  |  |  |  |  | $897.4 |  |  |  |  |  |  |
At December 31, the fair values of IPL’s and WPL’s qualified and non-qualified defined benefit pension plan assets associated with IPL’s and WPL’s current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored plans that were directly assigned to IPL and WPL, along with the percentage these assets represent of the fair values by asset category and fair value hierarchy level shown in the above table were as follows (dollars in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Fair values of directly assigned amounts | $136.5 |  | $127.4 |  | $102.2 |  | $97.0
Percentage represented | 14.1% |  | 14.2% |  | 10.6% |  | 10.8%
At December 31, the fair values of IPL’s qualified defined benefit pension plan assets by asset category and fair value hierarchy level were as follows (in millions):
IPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $14.6 |  |  |  | $— |  |  |  | $14.6 |  |  |  | $— |  |  |  | $39.1 |  |  |  | $39.1 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 43.1 |  |  | 43.1 |  |  | — |  |  | — |  |  | 36.8 |  |  | 36.8 |  |  | — |  |  | — |
U.S. large cap value | 36.0 |  |  | — |  |  | 36.0 |  |  | — |  |  | 30.5 |  |  | — |  |  | 30.5 |  |  | — |
U.S. large cap growth | 35.3 |  |  | — |  |  | 35.3 |  |  | — |  |  | 30.5 |  |  | — |  |  | 30.5 |  |  | — |
U.S. small cap value | 10.2 |  |  | — |  |  | 10.2 |  |  | — |  |  | 8.6 |  |  | — |  |  | 8.6 |  |  | — |
U.S. small cap growth | 8.3 |  |  | 8.3 |  |  | — |  |  | — |  |  | 7.2 |  |  | 7.2 |  |  | — |  |  | — |
International - developed markets | 51.3 |  |  | 26.8 |  |  | 24.5 |  |  | — |  |  | 42.1 |  |  | 21.8 |  |  | 20.3 |  |  | — |
International - emerging markets | 12.9 |  |  | 12.9 |  |  | — |  |  | — |  |  | 10.1 |  |  | 10.1 |  |  | — |  |  | — |
Global asset allocation securities | 31.5 |  |  | 18.8 |  |  | 12.7 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 10.2 |  |  | — |  |  | 10.2 |  |  | — |  |  | 19.0 |  |  | — |  |  | 19.0 |  |  | — |
Government and agency obligations | 16.4 |  |  | — |  |  | 16.4 |  |  | — |  |  | 29.2 |  |  | — |  |  | 29.2 |  |  | — |
Fixed income funds | 54.3 |  |  | 0.1 |  |  | 54.2 |  |  | — |  |  | 48.8 |  |  | 0.1 |  |  | 48.7 |  |  | — |
Securities lending invested collateral | 1.5 |  |  | — |  |  | 1.0 |  |  | 0.5 |  |  | 3.1 |  |  | 1.6 |  |  | 0.9 |  |  | 0.6 |
| 325.6 |  |  |  | $110.0 |  |  |  | $215.1 |  |  |  | $0.5 |  |  | 305.0 |  |  |  | $116.7 |  |  |  | $187.7 |  |  |  | $0.6 |
Accrued investment income | 0.2 |  |  |  |  |  |  |  |  | 0.4 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (0.5 | ) |  |  |  |  |  |  |  | (1.6 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (3.0 | ) |  |  |  |  |  |  |  | (5.1 | ) |  |  |  |  |  |
Total pension plan assets |  | $322.3 |  |  |  |  |  |  |  |  |  | $298.7 |  |  |  |  |  |  |
At December 31, the fair values of WPL’s qualified defined benefit pension plan assets by asset category and fair value hierarchy level were as follows (in millions):
WPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $14.2 |  |  |  | $— |  |  |  | $14.2 |  |  |  | $— |  |  |  | $37.9 |  |  |  | $37.9 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 41.8 |  |  | 41.8 |  |  | — |  |  | — |  |  | 35.7 |  |  | 35.7 |  |  | — |  |  | — |
U.S. large cap value | 35.0 |  |  | — |  |  | 35.0 |  |  | — |  |  | 29.6 |  |  | — |  |  | 29.6 |  |  | — |
U.S. large cap growth | 34.3 |  |  | — |  |  | 34.3 |  |  | — |  |  | 29.5 |  |  | — |  |  | 29.5 |  |  | — |
U.S. small cap value | 9.9 |  |  | — |  |  | 9.9 |  |  | — |  |  | 8.3 |  |  | — |  |  | 8.3 |  |  | — |
U.S. small cap growth | 8.1 |  |  | 8.1 |  |  | — |  |  | — |  |  | 7.0 |  |  | 7.0 |  |  | — |  |  | — |
International - developed markets | 49.9 |  |  | 26.1 |  |  | 23.8 |  |  | — |  |  | 40.8 |  |  | 21.1 |  |  | 19.7 |  |  | — |
International - emerging markets | 12.5 |  |  | 12.5 |  |  | — |  |  | — |  |  | 9.8 |  |  | 9.8 |  |  | — |  |  | — |
Global asset allocation securities | 30.7 |  |  | 18.3 |  |  | 12.4 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 9.9 |  |  | — |  |  | 9.9 |  |  | — |  |  | 18.4 |  |  | — |  |  | 18.4 |  |  | — |
Government and agency obligations | 16.0 |  |  | — |  |  | 16.0 |  |  | — |  |  | 28.3 |  |  | — |  |  | 28.3 |  |  | — |
Fixed income funds | 52.8 |  |  | 0.1 |  |  | 52.7 |  |  | — |  |  | 47.4 |  |  | 0.1 |  |  | 47.3 |  |  | — |
Securities lending invested collateral | 1.4 |  |  | — |  |  | 0.9 |  |  | 0.5 |  |  | 3.0 |  |  | 1.5 |  |  | 0.9 |  |  | 0.6 |
| 316.5 |  |  |  | $106.9 |  |  |  | $209.1 |  |  |  | $0.5 |  |  | 295.7 |  |  |  | $113.1 |  |  |  | $182.0 |  |  |  | $0.6 |
Accrued investment income | 0.2 |  |  |  |  |  |  |  |  | 0.3 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (0.5 | ) |  |  |  |  |  |  |  | (1.5 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (3.0 | ) |  |  |  |  |  |  |  | (4.9 | ) |  |  |  |  |  |
Total pension plan assets |  | $313.2 |  |  |  |  |  |  |  |  |  | $289.6 |  |  |  |  |  |  |
At December 31, the fair values of other postretirement benefits plans assets by asset category and fair value hierarchy level were as follows (in millions):
Alliant Energy | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $8.4 |  |  |  | $— |  |  |  | $8.4 |  |  |  | $— |  |  |  | $14.0 |  |  |  | $14.0 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 32.9 |  |  | 32.9 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 2.8 |  |  | 2.8 |  |  | — |  |  | — |  |  | 37.1 |  |  | 37.1 |  |  | — |  |  | — |
U.S. large cap value | 2.4 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |
U.S. large cap growth | 2.3 |  |  | — |  |  | 2.3 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |
U.S. mid cap core | — |  |  | — |  |  | — |  |  | — |  |  | 17.8 |  |  | 17.8 |  |  | — |  |  | — |
U.S. small cap core | — |  |  | — |  |  | — |  |  | — |  |  | 4.7 |  |  | 4.7 |  |  | — |  |  | — |
U.S. small cap value | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.6 |  |  | — |  |  | 0.6 |  |  | — |
U.S. small cap growth | 0.6 |  |  | 0.6 |  |  | — |  |  | — |  |  | 0.5 |  |  | 0.5 |  |  | — |  |  | — |
International - blend | 14.3 |  |  | 14.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 3.4 |  |  | 1.8 |  |  | 1.6 |  |  | — |  |  | 3.3 |  |  | 1.7 |  |  | 1.6 |  |  | — |
International - emerging markets | 0.8 |  |  | 0.8 |  |  | — |  |  | — |  |  | 0.8 |  |  | 0.8 |  |  | — |  |  | — |
Global asset allocation securities | 30.4 |  |  | 29.6 |  |  | 0.8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 6.1 |  |  | — |  |  | 6.1 |  |  | — |
Government and agency obligations | 1.1 |  |  | — |  |  | 1.1 |  |  | — |  |  | 5.6 |  |  | — |  |  | 5.6 |  |  | — |
Fixed income funds | 22.4 |  |  | 18.8 |  |  | 3.6 |  |  | — |  |  | 25.4 |  |  | 21.6 |  |  | 3.8 |  |  | — |
Securities lending invested collateral | 0.1 |  |  | — |  |  | 0.1 |  |  | — |  |  | 0.4 |  |  | 0.2 |  |  | 0.1 |  |  | 0.1 |
| 123.3 |  |  |  | $101.6 |  |  |  | $21.7 |  |  |  | $— |  |  | 121.1 |  |  |  | $98.4 |  |  |  | $22.6 |  |  |  | $0.1 |
Accrued investment income | — |  |  |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | — |  |  |  |  |  |  |  |  | (0.2 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (0.2 | ) |  |  |  |  |  |  |  | (0.6 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $123.1 |  |  |  |  |  |  |  |  |  | $120.4 |  |  |  |  |  |  |
IPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $3.3 |  |  |  | $— |  |  |  | $3.3 |  |  |  | $— |  |  |  | $2.1 |  |  |  | $2.1 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 24.3 |  |  | 24.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 0.8 |  |  | 0.8 |  |  | — |  |  | — |  |  | 29.3 |  |  | 29.3 |  |  | — |  |  | — |
U.S. large cap value | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.8 |  |  | — |  |  | 0.8 |  |  | — |
U.S. large cap growth | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.8 |  |  | — |  |  | 0.8 |  |  | — |
U.S. mid cap core | — |  |  | — |  |  | — |  |  | — |  |  | 14.7 |  |  | 14.7 |  |  | — |  |  | — |
U.S. small cap value | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 0.2 |  |  | — |
U.S. small cap growth | 0.2 |  |  | 0.2 |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.2 |  |  | — |  |  | — |
International - blend | 10.6 |  |  | 10.6 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 1.0 |  |  | 0.5 |  |  | 0.5 |  |  | — |  |  | 1.2 |  |  | 0.6 |  |  | 0.6 |  |  | — |
International - emerging markets | 0.2 |  |  | 0.2 |  |  | — |  |  | — |  |  | 0.3 |  |  | 0.3 |  |  | — |  |  | — |
Global asset allocation securities | 21.5 |  |  | 21.3 |  |  | 0.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 4.6 |  |  | — |  |  | 4.6 |  |  | — |
Government and agency obligations | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 4.1 |  |  | — |  |  | 4.1 |  |  | — |
Fixed income funds | 14.9 |  |  | 13.9 |  |  | 1.0 |  |  | — |  |  | 16.5 |  |  | 15.1 |  |  | 1.4 |  |  | — |
Securities lending invested collateral | — |  |  | — |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.1 |  |  | 0.1 |  |  | — |
| 78.9 |  |  |  | $71.8 |  |  |  | $7.1 |  |  |  | $— |  |  | 75.0 |  |  |  | $62.4 |  |  |  | $12.6 |  |  |  | $— |
Accrued investment income | — |  |  |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |
Due to borrowers for securities lending program | (0.1 | ) |  |  |  |  |  |  |  | (0.4 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $78.8 |  |  |  |  |  |  |  |  |  | $74.7 |  |  |  |  |  |  |
WPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $3.9 |  |  |  | $— |  |  |  | $3.9 |  |  |  | $— |  |  |  | $10.5 |  |  |  | $10.5 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 3.1 |  |  | 3.1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 1.3 |  |  | 1.3 |  |  | — |  |  | — |  |  | 1.2 |  |  | 1.2 |  |  | — |  |  | — |
U.S. large cap value | 1.2 |  |  | — |  |  | 1.2 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
U.S. large cap growth | 1.1 |  |  | — |  |  | 1.1 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
U.S. small cap core | — |  |  | — |  |  | — |  |  | — |  |  | 4.7 |  |  | 4.7 |  |  | — |  |  | — |
U.S. small cap value | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 0.3 |  |  | — |
U.S. small cap growth | 0.3 |  |  | 0.3 |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.2 |  |  | — |  |  | — |
International - blend | 1.3 |  |  | 1.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 1.6 |  |  | 0.8 |  |  | 0.8 |  |  | — |  |  | 1.3 |  |  | 0.7 |  |  | 0.6 |  |  | — |
International - emerging markets | 0.4 |  |  | 0.4 |  |  | — |  |  | — |  |  | 0.3 |  |  | 0.3 |  |  | — |  |  | — |
Global asset allocation securities | 3.6 |  |  | 3.2 |  |  | 0.4 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 1.1 |  |  | — |  |  | 1.1 |  |  | — |
Government and agency obligations | 0.5 |  |  | — |  |  | 0.5 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
Fixed income funds | 3.5 |  |  | 1.8 |  |  | 1.7 |  |  | — |  |  | 2.6 |  |  | 1.0 |  |  | 1.6 |  |  | — |
Securities lending invested collateral | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |  |  | 0.1 |  |  | — |  |  | — |
| 22.4 |  |  |  | $12.2 |  |  |  | $10.2 |  |  |  | $— |  |  | 25.3 |  |  |  | $18.7 |  |  |  | $6.6 |  |  |  | $— |
Due to brokers, net (pending trades with brokers) | — |  |  |  |  |  |  |  |  | (0.1 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (0.1 | ) |  |  |  |  |  |  |  | (0.1 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $22.3 |  |  |  |  |  |  |  |  |  | $25.1 |  |  |  |  |  |  |
For the various defined benefit pension and other postretirement benefits plans, Alliant Energy common stock represented less than 1% of total plan assets at December 31, 2012 and 2011. Cash Balance Plan - Alliant Energy’s defined benefit pension plans include the Cash Balance Plan that provides benefits for certain non-bargaining unit employees. The Cash Balance Plan has been closed to new hires since 2005. Effective 2008, Alliant Energy amended the Cash Balance Plan by discontinuing additional contributions into employees’ Cash Balance Plan accounts and increased its level of contributions to its 401(k) Savings Plan. In 2009, Alliant Energy amended the Cash Balance Plan by changing participants’ future interest credit formula to use the annual change in the consumer price index. This amendment provides participants an interest crediting rate that is 3% more than the annual change in the consumer price index. Refer to Note 13(c) for discussion of a class-action lawsuit filed against the Cash Balance Plan in 2008 and an agreement Alliant Energy reached with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. 401(k) Savings Plans - A significant number of Alliant Energy, IPL and WPL employees participate in defined contribution retirement plans (401(k) savings plans). Alliant Energy common stock represented 12.5% and 14.6% of total assets held in 401(k) savings plans at December 31, 2012 and 2011, respectively. Costs related to the 401(k) savings plans, which are partially based on the participants’ level of contribution, were as follows (in millions):
| Alliant Energy |  | IPL (a) |  | WPL (a)
| 2012 |  | 2011 |  | 2010 |  | 2012 |  |  | 2011 |  |  | 2010 |  |  | 2012 |  | 2011 |  | 2010
401(k) costs |  | $18.5 |  |  |  | $18.4 |  |  |  | $18.5 |  |  |  | $9.6 |  |  |  | $9.2 |  |  |  | $8.8 |  |  |  | $8.1 |  |  |  | $8.4 |  |  |  | $8.9 |
(a) | IPL’s and WPL’s amounts include allocated costs associated with Corporate Services employees.
(b) Equity-based Compensation Plans - In 2010, Alliant Energy’s shareowners approved the Alliant Energy 2010 Omnibus Incentive Plan (OIP), which permits the grant of stock options, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards and performance-based cash awards to key employees. At December 31, 2012, performance shares and restricted stock were outstanding and 4.2 million shares of Alliant Energy’s common stock remained available for grants under the OIP. Upon shareowner approval of the OIP, the Alliant Energy 2002 Equity Incentive Plan (EIP) terminated resulting in no new awards authorized to be granted under the EIP. All awards previously granted under the EIP that are still outstanding remain valid and continue to be subject to all of the terms and conditions of the EIP. At December 31, 2012, non-qualified stock options, restricted stock and performance shares were outstanding under the EIP and another predecessor plan under which new awards can no longer be granted. Alliant Energy satisfies payouts related to equity awards under the OIP and EIP through the issuance of new shares of its common stock. Alliant Energy also has the Alliant Energy Director Long Term Incentive Plan (DLIP), which permits the grant of long-term performance-based awards, including performance units and restricted cash awards to certain key employees. At December 31, 2012, performance units and performance contingent cash awards were outstanding under the DLIP. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash. A summary of compensation expense (allocated to IPL and WPL) and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Compensation expense |  | $6.9 |  |  |  | $10.1 |  |  |  | $7.5 |  |  |  | $3.6 |  |  |  | $5.5 |  |  |  | $4.0 |  |  |  | $3.0 |  |  |  | $4.1 |  |  |  | $3.0 |
Income tax benefits | 2.8 |  |  | 4.0 |  |  | 3.0 |  |  | 1.5 |  |  | 2.2 |  |  | 1.6 |  |  | 1.2 |  |  | 1.7 |  |  | 1.2 |
As of December 31, 2012, total unrecognized compensation cost related to share-based compensation awards was $6.1 million, which is expected to be recognized over a weighted average period of between 1 and 2 years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is primarily recorded in “Utility - Other operation and maintenance” in the Consolidated Statements of Income. Performance Shares and Units - Payouts of performance shares and units to key employees are contingent upon achievement over 3-year periods of specified performance criteria, which currently include metrics of total shareowner return relative to investor-owned utility peer groups. Payouts of nonvested performance shares and units issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of these performance shares and units to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Payouts of nonvested performance shares and units issued prior to 2012 are prorated at retirement, death, disability or involuntary termination without cause based on time worked during the full or entire performance period and achievement of the performance criteria. Participants’ nonvested performance shares and units are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested performance shares and units do not have non-forfeitable rights to dividends when dividends are paid to common shareowners. Alliant Energy assumes it will make future payouts of its performance shares and units in cash; therefore, performance shares and units are accounted for as liability awards. Performance Shares - Performance shares can be paid out in shares of Alliant Energy’s common stock, cash or a combination of cash and stock and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance shares activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares (a) |  | Shares (a) |  | Shares (a)
Nonvested shares, January 1 | 236,979 |  |  | 234,518 |  |  | 256,579 |
Granted | 45,612 |  |  | 64,217 |  |  | 72,487 |
Vested (b) | (111,980 | ) |  | (57,838 | ) |  | — |
Forfeited (c) | (25,334 | ) |  | (3,918 | ) |  | (94,548 | )
Nonvested shares, December 31 | 145,277 |  |  | 236,979 |  |  | 234,518 |
(a) | Share amounts represent the target number of performance shares. Each performance share’s value is based on the price of one share of Alliant Energy’s common stock at the end of the performance period. The actual number of shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares.
(b) | In 2012, 111,980 performance shares granted in 2009 vested at 162.5% of the target, resulting in payouts valued at $8.0 million, which consisted of a combination of cash and common stock (6,399 shares). In 2011, 57,838 performance shares granted in 2008 vested at 75% of the target, resulting in payouts valued at $1.6 million, which consisted of a combination of cash and common stock (1,387 shares).
(c) | In 2010, 57,100 performance shares granted in 2007 were forfeited without payout because the specified performance criteria for such shares were not met. The remaining forfeitures during 2012, 2011 and 2010 were primarily caused by retirements and voluntary terminations of participants.
Performance Units - Performance units must be paid out in cash and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance unit activity was as follows:
| 2012 |  | 2011 |  | 2010
| Units (a) |  | Units (a) |  | Units (a)
Nonvested units, January 1 | 42,996 |  |  | 23,128 |  |  | — |
Granted | 24,686 |  |  | 23,975 |  |  | 23,795 |
Forfeited | (2,713 | ) |  | (4,107 | ) |  | (667 | )
Nonvested units, December 31 | 64,969 |  |  | 42,996 |  |  | 23,128 |
(a) | Unit amounts represent the target number of performance units. Each performance unit’s value is based on the average price of one share of Alliant Energy’s common stock on the grant date of the award. The actual payout for performance units is dependent upon actual performance and may range from zero to 200% of the target number of units.
Fair Value of Awards - Information related to fair values of nonvested performance shares and units at December 31, 2012, by year of grant, were as follows:
| Performance Shares |  | Performance Units
| 2012 Grant |  | 2011 Grant |  | 2010 Grant |  | 2012 Grant |  | 2011 Grant |  | 2010 Grant
Nonvested awards | 45,612 |  |  | 45,235 |  |  | 54,430 |  |  | 23,969 |  |  | 21,095 |  |  | 19,905 |
Alliant Energy common stock closing price on December 31, 2012 |  | $43.91 |  |  |  | $43.91 |  |  |  | $43.91 |  |  |  |  |  |  |
Alliant Energy common stock average price on grant date |  |  |  |  |  |  |  | $43.05 |  |  |  | $38.75 |  |  |  | $32.56 |
Estimated payout percentage based on performance criteria | 89 | % |  | 107 | % |  | 198 | % |  | 89 | % |  | 107 | % |  | 198 | %
Fair values of each nonvested award |  | $39.08 |  |  |  | $46.98 |  |  |  | $86.72 |  |  |  | $38.31 |  |  |  | $41.46 |  |  |  | $64.30 |
At December 31, 2012, fair values of nonvested performance shares and units were calculated using a Monte Carlo simulation to determine the anticipated total shareowner returns of Alliant Energy and its investor-owned utility peer groups. Expected volatility was based on historical volatilities using daily stock prices over the past three years. Expected dividend yields were calculated based on the most recent quarterly dividend rates announced prior to the measurement date and stock prices at the measurement date. The risk-free interest rate was based on the three-year U.S. Treasury rate in effect as of the measurement date. Restricted Stock - Restricted stock consists of time-based and performance-contingent restricted stock. Time-based Restricted Stock - The current restriction period for outstanding time-based restricted stock is up to three years. Nonvested shares of time-based restricted stock generally become vested upon retirement. Compensation costs related to awards granted to retirement-eligible employees are generally expensed on the date of grant. Participants’ nonvested time-based restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Participants’ nonvested time-based restricted stock issued prior to 2012 is fully vested in the event of retirement, death, disability or involuntary termination without cause. The fair value of time-based restricted stock is based on the average market price at the grant date. A summary of the time-based restricted stock activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value
Nonvested shares, January 1 | 35,800 |  |  |  | $30.87 |  |  | 70,033 |  |  |  | $32.27 |  |  | 125,349 |  |  |  | $32.47 |
Granted | — |  |  | — |  |  | 5,000 |  |  | 39.86 |  |  | — |  |  | — |
Vested | (32,466 | ) |  | 29.95 |  |  | (38,633 | ) |  | 34.60 |  |  | (54,016 | ) |  | 32.72 |
Forfeited | — |  |  | — |  |  | (600 | ) |  | 29.41 |  |  | (1,300 | ) |  | 32.78 |
Nonvested shares, December 31 | 3,334 |  |  | 39.86 |  |  | 35,800 |  |  | 30.87 |  |  | 70,033 |  |  | 32.27 |
Performance-contingent Restricted Stock - Vesting of performance-contingent restricted stock grants are based on the achievement of certain performance targets (currently specified earnings growth). The performance metric for the 2012, 2011 and 2010 grants is consolidated net income growth. If performance targets are not met within the performance period, which currently ranges from two to four years, these restricted stock grants are forfeited. Payouts of nonvested performance-contingent restricted stock issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of this performance-contingent restricted stock to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Nonvested shares of performance-contingent restricted stock issued prior to 2012 are prorated at retirement based on time worked during the full or entire performance period and vest only if and when the performance criteria are met. Participants’ nonvested performance-contingent restricted stock is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. The fair value of performance-contingent restricted stock is based on the average market price at the grant date. A summary of the performance-contingent restricted stock activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value
Nonvested shares, January 1 | 301,738 |  |  |  | $32.60 |  |  | 296,190 |  |  |  | $32.32 |  |  | 226,007 |  |  |  | $32.25 |
Granted | 45,612 |  |  | 43.05 |  |  | 64,217 |  |  | 38.75 |  |  | 72,487 |  |  | 32.56 |
Vested (a) | (65,172 | ) |  | 32.56 |  |  | (53,274 | ) |  | 37.93 |  |  | — |  |  | — |
Forfeited (b) | (70,527 | ) |  | 39.93 |  |  | (5,395 | ) |  | 38.00 |  |  | (2,304 | ) |  | 32.56 |
Nonvested shares, December 31 | 211,651 |  |  | 32.42 |  |  | 301,738 |  |  | 32.60 |  |  | 296,190 |  |  | 32.32 |
(a) | In 2012 and 2011, 65,172 and 53,274 performance-contingent restricted shares granted in 2010 and 2007, respectively, vested because the specified performance criteria for such shares were met.
(b) | In 2012, 65,516 performance-contingent restricted shares granted in 2008 were forfeited because the specified performance criteria for such shares were not met. The remaining forfeitures during 2012, 2011 and 2010 were primarily caused by retirements and terminations of participants.
Non-qualified Stock Options - Options were granted at the market price of the shares on the date of grant, vested over three years and expire no later than 10 years after the grant date. Alliant Energy has not granted any options since 2004. A summary of the stock option activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Exercise Price |  | Shares |  | Weighted Average Exercise Price |  | Shares |  | Weighted Average Exercise Price
Outstanding, January 1 | 63,889 |  |  |  | $24.21 |  |  | 163,680 |  |  |  | $24.51 |  |  | 384,331 |  |  |  | $27.02 |
Exercised | (38,711 | ) |  | 24.41 |  |  | (99,791 | ) |  | 24.71 |  |  | (191,433 | ) |  | 28.93 |
Expired | — |  |  | — |  |  | — |  |  | — |  |  | (29,218 | ) |  | 28.59 |
Outstanding and exercisable, December 31 | 25,178 |  |  | 23.89 |  |  | 63,889 |  |  | 24.21 |  |  | 163,680 |  |  | 24.51 |
The weighted average remaining contractual term for options outstanding and exercisable at December 31, 2012 was 1 year. The aggregate intrinsic value of options outstanding and exercisable at December 31, 2012 was $0.5 million. Other information related to stock option activity was as follows (in millions):
| 2012 |  | 2011 |  | 2010
Cash received from stock options exercised |  | $0.9 |  |  |  | $2.5 |  |  |  | $5.5 |
Aggregate intrinsic value of stock options exercised | 0.8 |  |  | 1.6 |  |  | 1.1 |
Income tax benefit from the exercise of stock options | 0.3 |  |  | 0.7 |  |  | 0.4 |
Performance Contingent Cash Awards - Performance contingent cash award payouts to key employees are based on the achievement of certain performance targets (currently specified consolidated net income growth). If performance targets are not met within the performance period, which currently ranges from two to four years, there are no payouts for these awards. Payouts of nonvested awards issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of these 2012 awards to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Nonvested awards issued prior to 2012 are prorated at retirement based on time worked during the full or entire performance period and achievement of the performance criteria. Participants’ nonvested awards are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Each performance contingent cash award’s value is based on the price of one share of Alliant Energy’s common stock at the end of the performance period. Alliant Energy accounts for performance contingent cash awards as liability awards because payouts will be made in the form of cash. A summary of the performance contingent cash awards activity was as follows:
| 2012 |  | 2011 |  | 2010
| Awards |  | Awards |  | Awards
Nonvested awards, January 1 | 46,676 |  |  | 23,428 |  |  | — |
Granted | 36,936 |  |  | 23,975 |  |  | 23,795 |
Vested (a) | (21,605 | ) |  | — |  |  | — |
Forfeited | (2,368 | ) |  | (727 | ) |  | (367 | )
Nonvested awards, December 31 | 59,639 |  |  | 46,676 |  |  | 23,428 |
(a) | In 2012, 21,605 performance contingent cash awards granted in 2010 vested, resulting in cash payouts valued at $0.9 million.
(c) Deferred Compensation Plan (DCP) - Alliant Energy maintains a DCP under which key employees may defer up to 100% of base salary and performance-based compensation and directors may elect to defer all or part of their retainer and committee fees. Key employees who have made the maximum allowed contribution to the Alliant Energy 401(k) Savings Plan may receive an additional credit to the DCP. Key employees and directors may elect to have their deferrals credited to a company stock account, an interest account or equity accounts based on certain benchmark funds. Company Stock Accounts - The DCP does not permit diversification of deferrals credited to the company stock account and all distributions from participants’ company stock accounts are made in the form of shares of Alliant Energy common stock. The deferred compensation obligations for participants’ company stock accounts are recorded in “Additional paid-in capital” and the shares of Alliant Energy common stock held in a rabbi trust to satisfy this obligation are recorded in “Shares in deferred compensation trust” on Alliant Energy’s Consolidated Balance Sheets. At December 31, the carrying value of the deferred compensation obligation for the company stock accounts and the shares in the deferred compensation trust based on the historical value of the shares of Alliant Energy common stock contributed to the rabbi trust, and the fair market value of the shares held in the rabbi trust were as follows (in millions):
| 2012 |  | 2011
Carrying value |  | $7.3 |  |  |  | $8.3 |
Fair market value | 9.5 |  |  | 11.6 |
Interest and Equity Accounts - Distributions from participants’ interest and equity accounts are in the form of cash payments. The deferred compensation obligations for participants’ interest and equity accounts are recorded in “Pension and other benefit obligations” on Alliant Energy’s and IPL’s Consolidated Balance Sheets. At December 31, the carrying value of Alliant Energy’s and IPL’s deferred compensation obligations for participants’ interest and equity accounts was as follows (in millions):
| Alliant Energy |  | IPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Carrying value | $16.3 |  | $20.5 |  | $5.0 |  | $5.0
WPL [Member] |
Benefit Plans | BENEFIT PLANS (a) Pension and Other Postretirement Benefits Plans - Alliant Energy, IPL and WPL provide retirement benefits to substantially all of their employees through various qualified and non-qualified non-contributory defined benefit pension plans, and/or through defined contribution plans (including 401(k) savings plans). Alliant Energy’s, IPL’s and WPL’s qualified and non-qualified non-contributory defined benefit pension plans are currently closed to new hires. Benefits of the non-contributory defined benefit pension plans are based on the plan participant’s years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant’s years of service, age, compensation and contributions. Alliant Energy, IPL and WPL also provide certain defined benefit postretirement health care and life benefits to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory. Assumptions - The assumptions for defined benefit pension and other postretirement benefits plans at the measurement date of December 31 were as follows (Not Applicable (N/A)):
Alliant Energy | Defined Benefit Pension Plans |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.11% |  | 4.86% |  | 5.56% |  | 3.82% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.86% |  | 5.56% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.50% |  | 7.00% |  | 6.90%
Rate of compensation increase | 3.50 | % | - | 4.50% |  | 3.50 | % | - | 4.50% |  | 3.50 | % | - | 4.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
IPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.20% |  | 4.95% |  | 5.70% |  | 3.76% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.95% |  | 5.70% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.40% |  | 7.30% |  | 7.10%
Rate of compensation increase | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
WPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Discount rate for benefit obligations | 4.20% |  | 4.95% |  | 5.70% |  | 3.81% |  | 4.60% |  | 5.25%
Discount rate for net periodic cost | 4.95% |  | 5.70% |  | 5.80% |  | 4.60% |  | 5.25% |  | 5.55%
Expected rate of return on plan assets | 7.90% |  | 7.90% |  | 8.00% |  | 7.00% |  | 6.30% |  | 6.30%
Rate of compensation increase | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50% |  | 3.50%
Medical cost trend on covered charges: |  |  |  |  |  |  |  |  |  |  |
Initial trend rate (end of year) | N/A |  | N/A |  | N/A |  | 7.50% |  | 8.00% |  | 7.00%
Ultimate trend rate | N/A |  | N/A |  | N/A |  | 5.00% |  | 5.00% |  | 5.00%
Expected rate of return on plan assets - The expected rate of return on plan assets is determined by analysis of projected asset class returns based on the target asset class allocations. Alliant Energy, IPL and WPL use a forward-looking building blocks approach and also review historical returns, survey information and capital market information to support the expected rate of return on plan assets assumption. Refer to “Investment Policy and Strategy for Plan Assets” below for additional information related to Alliant Energy’s, IPL’s and WPL’s investment policy and strategy and mix of assets for the pension and other postretirement benefits plans. Medical cost trend on covered charges - The assumed medical trend rates are critical assumptions in determining the service and interest cost and accumulated postretirement benefit obligation related to postretirement benefits costs. A 1% change in the medical trend rates for 2012, holding all other assumptions constant, would have the following effects (in millions):
| Alliant Energy |  | IPL |  | WPL
| 1% Increase |  | 1% Decrease |  | 1% Increase |  | 1% Decrease |  | 1% Increase |  | 1% Decrease
Effect on total of service and interest cost components |  | $0.4 |  |  |  | ($0.4 | ) |  |  | $0.2 |  |  |  | ($0.2 | ) |  |  | $0.2 |  |  |  | ($0.2 | )
Effect on postretirement benefit obligation | 2.6 |  |  | (2.4 | ) |  | 1.2 |  |  | (1.1 | ) |  | 1.2 |  |  | (1.2 | )
Net Periodic Benefit Costs (Credits) - The components of net periodic benefit costs (credits) for Alliant Energy’s, IPL’s and WPL’s sponsored defined benefit pension and other postretirement benefits plans, and defined benefit pension plans amounts directly assigned to IPL and WPL, are included in the tables below (in millions). In the “IPL” and “WPL” tables below, the qualified defined benefit pension plans costs represent only those respective costs for IPL’s and WPL’s bargaining unit employees covered under the plans that are sponsored by IPL and WPL, respectively. Also in the “IPL” and “WPL” tables below, the other postretirement benefits plans costs (credits) represent costs (credits) for all IPL and WPL employees, respectively. The “Directly assigned defined benefit pension plans” tables below include amounts directly assigned to each of IPL and WPL related to IPL’s and WPL’s current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Alliant Energy | Defined Benefit Pension Plans |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $13.5 |  |  |  | $11.4 |  |  |  | $11.9 |  |  |  | $6.9 |  |  |  | $7.0 |  |  |  | $9.3 |
Interest cost | 51.6 |  |  | 52.0 |  |  | 52.3 |  |  | 10.2 |  |  | 12.3 |  |  | 14.9 |
Expected return on plan assets (b) | (68.8 | ) |  | (63.8 | ) |  | (62.1 | ) |  | (7.5 | ) |  | (7.9 | ) |  | (7.7 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Transition obligation | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |
Prior service cost (credit) | 0.3 |  |  | 0.7 |  |  | 0.9 |  |  | (12.0 | ) |  | (10.0 | ) |  | (2.4 | )
Actuarial loss | 33.3 |  |  | 21.1 |  |  | 23.8 |  |  | 6.3 |  |  | 5.3 |  |  | 7.4 |
Additional benefit costs (d) | 0.1 |  |  | 10.2 |  |  | — |  |  | — |  |  | — |  |  | — |
Settlement losses (e) | 5.4 |  |  | 1.1 |  |  | 1.4 |  |  | — |  |  | — |  |  | — |
|  | $35.4 |  |  |  | $32.7 |  |  |  | $28.2 |  |  |  | $3.9 |  |  |  | $6.7 |  |  |  | $21.6 |
IPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $7.5 |  |  |  | $6.1 |  |  |  | $6.2 |  |  |  | $3.0 |  |  |  | $2.6 |  |  |  | $3.4 |
Interest cost | 17.1 |  |  | 16.7 |  |  | 16.5 |  |  | 4.4 |  |  | 5.5 |  |  | 6.8 |
Expected return on plan assets (b) | (23.0 | ) |  | (20.0 | ) |  | (19.5 | ) |  | (5.1 | ) |  | (5.4 | ) |  | (5.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Transition obligation | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |
Prior service cost (credit) | 0.4 |  |  | 0.5 |  |  | 0.6 |  |  | (6.3 | ) |  | (5.0 | ) |  | (1.1 | )
Actuarial loss | 10.2 |  |  | 5.7 |  |  | 7.2 |  |  | 3.5 |  |  | 2.9 |  |  | 4.0 |
|  | $12.2 |  |  |  | $9.0 |  |  |  | $11.0 |  |  |  | ($0.5 | ) |  |  | $0.6 |  |  |  | $7.9 |
WPL | Qualified Defined Benefit Pension Plan |  | Other Postretirement Benefits Plans (a)
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Service cost |  | $5.2 |  |  |  | $4.5 |  |  |  | $4.9 |  |  |  | $2.7 |  |  |  | $2.9 |  |  |  | $3.6 |
Interest cost | 16.4 |  |  | 16.1 |  |  | 15.7 |  |  | 4.1 |  |  | 4.9 |  |  | 5.5 |
Expected return on plan assets (b) | (22.3 | ) |  | (20.0 | ) |  | (19.1 | ) |  | (1.3 | ) |  | (1.3 | ) |  | (1.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Prior service cost (credit) | 0.5 |  |  | 0.5 |  |  | 0.5 |  |  | (3.9 | ) |  | (3.4 | ) |  | (0.7 | )
Actuarial loss | 12.1 |  |  | 7.1 |  |  | 8.5 |  |  | 2.3 |  |  | 2.1 |  |  | 2.5 |
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
|  | $12.0 |  |  |  | $8.2 |  |  |  | $10.5 |  |  |  | $3.9 |  |  |  | $5.2 |  |  |  | $9.6 |
Directly assigned defined benefit pension plans | IPL |  | WPL
2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Interest cost |  | $7.0 |  |  |  | $7.3 |  |  |  | $7.8 |  |  |  | $5.2 |  |  |  | $5.5 |  |  |  | $5.6 |
Expected return on plan assets (b) | (9.6 | ) |  | (9.7 | ) |  | (9.7 | ) |  | (7.3 | ) |  | (7.3 | ) |  | (7.3 | )
Amortization of (c): |  |  |  |  |  |  |  |  |  |  |
Prior service credit | (0.2 | ) |  | (0.2 | ) |  | (0.3 | ) |  | (0.1 | ) |  | (0.2 | ) |  | (0.2 | )
Actuarial loss | 3.9 |  |  | 3.0 |  |  | 2.9 |  |  | 3.6 |  |  | 3.0 |  |  | 2.8 |
Additional benefit costs (d) | — |  |  | 2.8 |  |  | — |  |  | — |  |  | 0.7 |  |  | — |
|  | $1.1 |  |  |  | $3.2 |  |  |  | $0.7 |  |  |  | $1.4 |  |  |  | $1.7 |  |  |  | $0.9 |
(a) | In 2011, Alliant Energy, IPL and WPL amended their defined benefit postretirement health care plans resulting in a revision to the method and level of coverage provided for participants more than 65 years of age. This amendment was determined to be a significant event, which required Alliant Energy, IPL and WPL to remeasure their defined benefit postretirement health care plans in 2011. The amendment resulted in a decrease in Alliant Energy’s, IPL’s and WPL’s postretirement benefit obligations of $55 million, $30 million and $16 million, respectively, in 2011 with the impact of the remeasurement on net periodic benefit costs being recognized prospectively from the remeasurement date. The impact of the remeasurement decreased Alliant Energy’s, IPL’s and WPL’s net periodic benefit costs by $11.3 million, $7.2 million, and $3.8 million in 2011, respectively. The discount rate used for the remeasurement was 5.20%. All other assumptions used for the remeasurement were consistent with the measurement assumptions used at December 31, 2010.
(b) | The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.
(c) | Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan (Cash Balance Plan) where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits. Unrecognized prior service costs (credits) for the postretirement benefits plans are amortized over the average future service period to full eligibility of the participants of each plan.
(d) | Alliant Energy reached an agreement with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. The agreement with the IRS required Alliant Energy to amend the Cash Balance Plan, which was completed in 2011 resulting in aggregate additional benefits of $10.2 million paid by Alliant Energy to certain former participants in the Cash Balance Plan in 2011. Alliant Energy recognized $10.2 million of additional benefits costs in 2011 related to these benefits. IPL recognized $6.3 million ($2.8 million directly assigned and $3.5 million allocated by Corporate Services) and WPL recognized $3.4 million ($0.7 million directly assigned and $2.7 million allocated by Corporate Services) of additional benefits costs in 2011 related to these benefits. Refer to Note 13(c) for additional information regarding the Cash Balance Plan.
(e) | Settlement losses related to payments made to retired executives of Alliant Energy.
Corporate Services provides services to IPL and WPL, and as a result, IPL and WPL are allocated pension and other postretirement benefits costs associated with Corporate Services employees. The following table includes the allocated qualified and non-qualified pension and other postretirement benefits costs associated with Corporate Services employees providing services to IPL and WPL (in millions):
| Pension Benefits Costs (a) |  | Other Postretirement Benefits Costs
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
IPL |  | $4.9 |  |  |  | $5.8 |  |  |  | $2.9 |  |  |  | $0.1 |  |  |  | $0.3 |  |  |  | $2.0 |
WPL | 3.6 |  |  | 4.2 |  |  | 1.9 |  |  | 0.1 |  |  | 0.2 |  |  | 1.3 |
(a) | Includes settlement losses related to payments made to retired executives of Alliant Energy in 2012. In 2011, additional qualified pension benefits costs resulting from the 2011 amendment to the Cash Balance Plan allocated to IPL and WPL by Corporate Services were $3.5 million and $2.7 million, respectively.
The estimated amortization from “Regulatory assets” and “Regulatory liabilities” on the Consolidated Balance Sheets and AOCL on Alliant Energy’s Consolidated Balance Sheet into net periodic benefit cost in 2013 is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
|  |  | Other |  | Qualified |  | Other |  | Qualified |  | Other
| Defined Benefit |  | Postretirement |  | Defined Benefit |  | Postretirement |  | Defined Benefit |  | Postretirement
| Pension Plans |  | Benefits Plans |  | Pension Plan |  | Benefits Plans |  | Pension Plan |  | Benefits Plans
Actuarial loss |  | $36.2 |  |  |  | $4.9 |  |  |  | $10.9 |  |  |  | $2.7 |  |  |  | $13.2 |  |  |  | $1.9 |
Prior service cost (credit) | 0.2 |  |  | (11.9 | ) |  | 0.4 |  |  | (6.3 | ) |  | 0.5 |  |  | (3.9 | )
|  | $36.4 |  |  |  | ($7.0 | ) |  |  | $11.3 |  |  |  | ($3.6 | ) |  |  | $13.7 |  |  |  | ($2.0 | )
Directly assigned defined benefit pension plans | IPL |  | WPL
Actuarial loss |  | $4.2 |  |  |  | $3.9 |
Prior service credit | (0.2 | ) |  | (0.2 | )
|  | $4.0 |  |  |  | $3.7 |
In addition to the estimated amortizations from “Regulatory assets” and “Regulatory liabilities” in the above tables for IPL and WPL, $1.3 million and $0.9 million, respectively, of amortizations are expected in 2013 from “Regulatory assets” and “Regulatory liabilities” associated with Corporate Services employees participating in other Alliant Energy sponsored plans allocated to IPL and WPL. Alliant Energy’s, IPL’s and WPL’s net periodic benefit costs are primarily included in “Utility - Other operation and maintenance” in the Consolidated Statements of Income. Benefit Plan Assets and Obligations - A reconciliation of the funded status of Alliant Energy’s qualified and non-qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on Alliant Energy’s Consolidated Balance Sheets at December 31 was as follows (in millions):
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $1,081.4 |  |  |  | $953.0 |  |  |  | $224.2 |  |  |  | $274.9 |
Service cost | 13.5 |  |  | 11.4 |  |  | 6.9 |  |  | 7.0 |
Interest cost | 51.6 |  |  | 52.0 |  |  | 10.2 |  |  | 12.3 |
Plan participants’ contributions | — |  |  | — |  |  | 2.7 |  |  | 6.4 |
Plan amendments (a) | — |  |  | 10.2 |  |  | — |  |  | (56.6 | )
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |
Actuarial (gain) loss | 135.4 |  |  | 126.2 |  |  | (1.6 | ) |  | (0.8 | )
Early Retiree Reinsurance Program (ERRP) proceeds | — |  |  | — |  |  | — |  |  | 0.6 |
Gross benefits paid | (74.5 | ) |  | (71.4 | ) |  | (19.2 | ) |  | (20.8 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 1.2 |
Net projected benefit obligation at December 31 | 1,207.5 |  |  | 1,081.4 |  |  | 223.2 |  |  | 224.2 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 897.4 |  |  | 823.0 |  |  | 120.4 |  |  | 122.7 |
Actual return on plan assets | 126.9 |  |  | 28.9 |  |  | 14.3 |  |  | 2.6 |
Employer contributions | 15.8 |  |  | 116.9 |  |  | 4.9 |  |  | 9.5 |
Plan participants’ contributions | — |  |  | — |  |  | 2.7 |  |  | 6.4 |
Gross benefits paid | (74.5 | ) |  | (71.4 | ) |  | (19.2 | ) |  | (20.8 | )
Fair value of plan assets at December 31 | 965.6 |  |  | 897.4 |  |  | 123.1 |  |  | 120.4 |
Under funded status at December 31 |  | ($241.9 | ) |  |  | ($184.0 | ) |  |  | ($100.1 | ) |  |  | ($103.8 | )
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Non-current assets |  | $— |  |  |  | $— |  |  |  | $3.5 |  |  |  | $1.3 |
Other current liabilities | (2.4 | ) |  | (4.6 | ) |  | (2.8 | ) |  | — |
Pension and other benefit obligations | (239.5 | ) |  | (179.4 | ) |  | (100.8 | ) |  | (105.1 | )
Net amount recognized at December 31 |  | ($241.9 | ) |  |  | ($184.0 | ) |  |  | ($100.1 | ) |  |  | ($103.8 | )
Amounts recognized in Regulatory Assets, Regulatory Liabilities and AOCL consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $533.4 |  |  |  | $494.8 |  |  |  | $62.1 |  |  |  | $76.7 |
Prior service credit | (7.2 | ) |  | (6.9 | ) |  | (40.5 | ) |  | (52.5 | )
|  | $526.2 |  |  |  | $487.9 |  |  |  | $21.6 |  |  |  | $24.2 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) and Alliant Energy’s Consolidated Statements of Common Equity for amounts recognized in “Regulatory assets” and “AOCL,” respectively, on Alliant Energy’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $2.7 million and $3.3 million, respectively, of regulatory liabilities were recognized related to Alliant Energy’s other postretirement benefits plans.
A reconciliation of the funded status of IPL’s sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on IPL’s Consolidated Balance Sheets, at December 31 was as follows (in millions):
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $344.5 |  |  |  | $293.8 |  |  |  | $97.5 |  |  |  | $128.5 |
Service cost | 7.5 |  |  | 6.1 |  |  | 3.0 |  |  | 2.6 |
Interest cost | 17.1 |  |  | 16.7 |  |  | 4.4 |  |  | 5.5 |
Plan participants’ contributions | — |  |  | — |  |  | 0.9 |  |  | 2.0 |
Plan amendments (a) | — |  |  | — |  |  | — |  |  | (30.1 | )
Actuarial (gain) loss | 38.2 |  |  | 45.2 |  |  | (1.4 | ) |  | (2.7 | )
ERRP proceeds | — |  |  | — |  |  | — |  |  | 0.2 |
Gross benefits paid | (18.9 | ) |  | (17.3 | ) |  | (8.4 | ) |  | (9.1 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 0.6 |
Net projected benefit obligation at December 31 | 388.4 |  |  | 344.5 |  |  | 96.0 |  |  | 97.5 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 298.7 |  |  | 256.9 |  |  | 74.7 |  |  | 77.5 |
Actual return on plan assets | 42.5 |  |  | 9.1 |  |  | 9.4 |  |  | 1.4 |
Employer contributions | — |  |  | 50.0 |  |  | 2.2 |  |  | 2.9 |
Plan participants’ contributions | — |  |  | — |  |  | 0.9 |  |  | 2.0 |
Gross benefits paid | (18.9 | ) |  | (17.3 | ) |  | (8.4 | ) |  | (9.1 | )
Fair value of plan assets at December 31 | 322.3 |  |  | 298.7 |  |  | 78.8 |  |  | 74.7 |
Under funded status at December 31 |  | ($66.1 | ) |  |  | ($45.8 | ) |  |  | ($17.2 | ) |  |  | ($22.8 | )
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Pension and other benefit obligations |  | ($66.1 | ) |  |  | ($45.8 | ) |  |  | ($17.2 | ) |  |  | ($22.8 | )
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $149.7 |  |  |  | $141.1 |  |  |  | $32.0 |  |  |  | $41.0 |
Prior service cost (credit) | 0.7 |  |  | 1.1 |  |  | (21.3 | ) |  | (27.6 | )
|  | $150.4 |  |  |  | $142.2 |  |  |  | $10.7 |  |  |  | $13.4 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on IPL’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $1.4 million and $2.8 million, respectively, of regulatory liabilities were recognized related to IPL’s other postretirement benefits plans.
A reconciliation of the funded status of WPL’s sponsored qualified defined benefit pension and other postretirement benefits plans to the amounts recognized on WPL’s Consolidated Balance Sheets, at December 31 was as follows (in millions):
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $332.5 |  |  |  | $283.3 |  |  |  | $89.6 |  |  |  | $103.3 |
Service cost | 5.2 |  |  | 4.5 |  |  | 2.7 |  |  | 2.9 |
Interest cost | 16.4 |  |  | 16.1 |  |  | 4.1 |  |  | 4.9 |
Plan participants’ contributions | — |  |  | — |  |  | 1.2 |  |  | 3.3 |
Plan amendments (a) | — |  |  | — |  |  | — |  |  | (18.2 | )
Additional benefit costs | 0.1 |  |  | — |  |  | — |  |  | — |
Actuarial loss | 43.4 |  |  | 43.3 |  |  | 0.3 |  |  | 2.3 |
ERRP proceeds | — |  |  | — |  |  | — |  |  | 0.2 |
Gross benefits paid | (17.4 | ) |  | (14.7 | ) |  | (8.8 | ) |  | (9.6 | )
Federal subsidy on other postretirement benefits paid | — |  |  | — |  |  | — |  |  | 0.5 |
Net projected benefit obligation at December 31 | 380.2 |  |  | 332.5 |  |  | 89.1 |  |  | 89.6 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 289.6 |  |  | 255.2 |  |  | 25.1 |  |  | 25.0 |
Actual return on plan assets | 41.0 |  |  | 9.1 |  |  | 2.5 |  |  | 0.9 |
Employer contributions | — |  |  | 40.0 |  |  | 2.3 |  |  | 5.5 |
Plan participants’ contributions | — |  |  | — |  |  | 1.2 |  |  | 3.3 |
Gross benefits paid | (17.4 | ) |  | (14.7 | ) |  | (8.8 | ) |  | (9.6 | )
Fair value of plan assets at December 31 | 313.2 |  |  | 289.6 |  |  | 22.3 |  |  | 25.1 |
Under funded status at December 31 |  | ($67.0 | ) |  |  | ($42.9 | ) |  |  | ($66.8 | ) |  |  | ($64.5 | )
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Non-current assets |  | $— |  |  |  | $— |  |  |  | $3.5 |  |  |  | $1.3 |
Other current liabilities | — |  |  | — |  |  | (2.8 | ) |  | — |
Pension and other benefit obligations | (67.0 | ) |  | (42.9 | ) |  | (67.5 | ) |  | (65.8 | )
Net amount recognized at December 31 |  | ($67.0 | ) |  |  | ($42.9 | ) |  |  | ($66.8 | ) |  |  | ($64.5 | )
Amounts recognized in Regulatory Assets and Regulatory Liabilities consist of (b): |  |  |  |  |  |  |
Net actuarial loss |  | $155.3 |  |  |  | $142.7 |  |  |  | $24.3 |  |  |  | $27.8 |
Prior service cost (credit) | 1.9 |  |  | 2.4 |  |  | (13.4 | ) |  | (17.3 | )
|  | $157.2 |  |  |  | $145.1 |  |  |  | $10.9 |  |  |  | $10.5 |
(a) | Refer to “Net Periodic Benefit Costs” above for additional information regarding plan amendments to the defined benefit pension and other postretirement benefits plans in 2011.
(b) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on WPL’s Consolidated Balance Sheets. At December 31, 2012 and 2011, $0.2 million and $0, respectively, of regulatory liabilities were recognized related to WPL’s other postretirement benefits plans.
Included in the following tables are accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and other postretirement benefits plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the December 31 measurement date (Not Applicable (N/A); in millions):
Alliant Energy | Defined Benefit |  | Other Postretirement
| Pension Plans |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $1,155.5 |  |  |  | $1,029.4 |  |  |  | $223.2 |  |  |  | $224.2 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 1,155.5 |  |  | 1,029.4 |  |  | 223.2 |  |  | 224.2 |
Fair value of plan assets | 965.6 |  |  | 897.4 |  |  | 123.1 |  |  | 120.4 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 1,207.5 |  |  | 1,081.4 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 965.6 |  |  | 897.4 |  |  | N/A |  |  | N/A |
IPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $359.6 |  |  |  | $314.6 |  |  |  | $96.0 |  |  |  | $97.5 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 359.6 |  |  | 314.6 |  |  | 96.0 |  |  | 97.5 |
Fair value of plan assets | 322.3 |  |  | 298.7 |  |  | 78.8 |  |  | 74.7 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 388.4 |  |  | 344.5 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 322.3 |  |  | 298.7 |  |  | N/A |  |  | N/A |
WPL | Qualified Defined Benefit |  | Other Postretirement
| Pension Plan |  | Benefits Plans
| 2012 |  | 2011 |  | 2012 |  | 2011
Accumulated benefit obligations |  | $363.7 |  |  |  | $314.7 |  |  |  | $89.1 |  |  |  | $89.6 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 363.7 |  |  | 314.7 |  |  | 89.1 |  |  | 89.6 |
Fair value of plan assets | 313.2 |  |  | 289.6 |  |  | 22.3 |  |  | 25.1 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 380.2 |  |  | 332.5 |  |  | N/A |  |  | N/A |
Fair value of plan assets | 313.2 |  |  | 289.6 |  |  | N/A |  |  | N/A |
The “Directly assigned defined benefit pension plans” table below includes amounts directly assigned to each of IPL and WPL related to their current and former non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans. A reconciliation of the funded status of the directly assigned qualified and non-qualified defined benefit pension plans to the amounts recognized on IPL’s and WPL’s Consolidated Balance Sheets at December 31 was as follows (in millions):
Directly assigned defined benefit pension plans | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Change in projected benefit obligation: |  |  |  |  |  |  |
Net projected benefit obligation at January 1 |  | $155.4 |  |  |  | $144.4 |  |  |  | $115.2 |  |  |  | $107.4 |
Interest cost | 7.0 |  |  | 7.3 |  |  | 5.2 |  |  | 5.5 |
Plan amendments | — |  |  | 2.8 |  |  | — |  |  | 0.7 |
Actuarial loss | 17.9 |  |  | 13.2 |  |  | 14.5 |  |  | 10.3 |
Gross benefits paid | (9.5 | ) |  | (12.3 | ) |  | (8.4 | ) |  | (8.7 | )
Net projected benefit obligation at December 31 | 170.8 |  |  | 155.4 |  |  | 126.5 |  |  | 115.2 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 127.4 |  |  | 127.6 |  |  | 97.0 |  |  | 95.6 |
Actual return on plan assets | 17.9 |  |  | 4.2 |  |  | 13.5 |  |  | 3.2 |
Employer contributions | 0.7 |  |  | 7.9 |  |  | 0.1 |  |  | 6.9 |
Gross benefits paid | (9.5 | ) |  | (12.3 | ) |  | (8.4 | ) |  | (8.7 | )
Fair value of plan assets at December 31 | 136.5 |  |  | 127.4 |  |  | 102.2 |  |  | 97.0 |
Under funded status at December 31 |  | ($34.3 | ) |  |  | ($28.0 | ) |  |  | ($24.3 | ) |  |  | ($18.2 | )
Directly assigned defined benefit pension plans | IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Amounts recognized on the Consolidated Balance Sheets consist of: |  |  |  |  |  |  |
Other current liabilities |  | ($0.8 | ) |  |  | ($0.8 | ) |  |  | ($0.2 | ) |  |  | ($0.2 | )
Pension and other benefit obligations | (33.5 | ) |  | (27.2 | ) |  | (24.1 | ) |  | (18.0 | )
Net amount recognized at December 31 |  | ($34.3 | ) |  |  | ($28.0 | ) |  |  | ($24.3 | ) |  |  | ($18.2 | )
Amounts recognized in Regulatory Assets (a): |  |  |  |  |  |  |
Net actuarial loss |  | $81.9 |  |  |  | $76.2 |  |  |  | $78.4 |  |  |  | $73.7 |
Prior service credit | (3.2 | ) |  | (3.4 | ) |  | (2.3 | ) |  | (2.4 | )
|  | $78.7 |  |  |  | $72.8 |  |  |  | $76.1 |  |  |  | $71.3 |
Accumulated benefit obligations |  | $170.8 |  |  |  | $155.4 |  |  |  | $126.5 |  |  |  | $115.2 |
(a) | Refer to Note 1(b) for amounts recognized in “Regulatory assets” on IPL’s and WPL’s Consolidated Balance Sheets.
In addition to the amounts recognized in “Regulatory assets and regulatory liabilities” in the above tables for IPL and WPL, “Regulatory assets” and “Regulatory liabilities” were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at December 31 as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Regulatory assets |  | $38.1 |  |  |  | $33.7 |  |  |  | $25.5 |  |  |  | $22.3 |
Regulatory liabilities | 0.6 |  |  | 0.3 |  |  | 0.4 |  |  | 0.2 |
Estimated Future Employer Contributions and Benefit Payments - Alliant Energy, IPL and WPL estimate that funding for the qualified defined benefit pension, non-qualified defined benefit pension and other postretirement benefits plans, and the directly assigned qualified and non-qualified defined benefit pension plans amounts, during 2013 will be as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Qualified defined benefit pension plans |  | $— |  |  |  | $— |  |  |  | $— |
Non-qualified defined benefit pension plans (a) | 2.4 |  |  | N/A |  |  | N/A |
Directly assigned defined benefit pension plans (b) | N/A |  |  | 0.8 |  |  | 0.2 |
Other postretirement benefits plans | 3.0 |  |  | — |  |  | 3.0 |
(a) | Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans.
(b) | Amounts directly assigned to IPL and WPL for non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Expected benefit payments, and the directly assigned qualified and non-qualified defined benefit pension benefits amounts, which reflect expected future service, as appropriate, are as follows (in millions):
Alliant Energy | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified and non-qualified defined benefit pension benefits |  | $61.9 |  |  |  | $64.7 |  |  |  | $68.5 |  |  |  | $66.6 |  |  |  | $69.2 |  |  |  | $374.1 |
Other postretirement benefits | 16.6 |  |  | 16.2 |  |  | 16.3 |  |  | 16.4 |  |  | 16.6 |  |  | 84.2 |
|  | $78.5 |  |  |  | $80.9 |  |  |  | $84.8 |  |  |  | $83.0 |  |  |  | $85.8 |  |  |  | $458.3 |
IPL | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified defined benefit pension benefits |  | $15.9 |  |  |  | $16.9 |  |  |  | $17.9 |  |  |  | $18.9 |  |  |  | $20.0 |  |  |  | $116.0 |
Directly assigned defined benefit pension benefits | 12.6 |  |  | 13.4 |  |  | 14.1 |  |  | 12.1 |  |  | 13.5 |  |  | 60.2 |
Other postretirement benefits | 8.0 |  |  | 7.3 |  |  | 7.2 |  |  | 7.1 |  |  | 7.2 |  |  | 35.9 |
|  | $36.5 |  |  |  | $37.6 |  |  |  | $39.2 |  |  |  | $38.1 |  |  |  | $40.7 |  |  |  | $212.1 |
WPL | 2013 |  | 2014 |  | 2015 |  | 2016 |  | 2017 |  | 2018 - 2022
Qualified defined benefit pension benefits |  | $14.4 |  |  |  | $15.2 |  |  |  | $16.1 |  |  |  | $17.0 |  |  |  | $18.0 |  |  |  | $108.7 |
Directly assigned defined benefit pension benefits | 10.5 |  |  | 10.2 |  |  | 11.4 |  |  | 9.8 |  |  | 9.5 |  |  | 43.0 |
Other postretirement benefits | 6.3 |  |  | 6.5 |  |  | 6.7 |  |  | 6.7 |  |  | 6.8 |  |  | 34.3 |
|  | $31.2 |  |  |  | $31.9 |  |  |  | $34.2 |  |  |  | $33.5 |  |  |  | $34.3 |  |  |  | $186.0 |
Investment Policy and Strategy for Plan Assets - Alliant Energy’s, IPL’s and WPL’s investment policies and their strategies employed with respect to assets of defined benefit pension and other postretirement benefits plans are to combine both preservation of principal and prudent and reasonable risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. It is recognized that risk and volatility are present with all types of investments. However, risk is mitigated at the total fund level through diversification by asset class including both U.S. and international equity exposure, the number of individual investments, and sector and industry limits. Defined Benefit Pension Plans Assets - For assets of defined benefit pension plans, the mix among asset classes is controlled by long-term asset allocation targets. Historical performance results and future expectations suggest that equity securities will provide higher total investment returns than debt securities over a long-term investment horizon. Consistent with the goals of meeting obligations to plan participants and minimizing benefit costs over the long-term, the defined benefit pension plans have a long-term investment posture more heavily weighted towards equity holdings. The asset allocation is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. Alliant Energy, IPL and WPL also use an overlay management service to help maintain target allocations and liquidity needs. The overlay manager is authorized to use derivative financial instruments to facilitate this service. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, margin trading, oil and gas limited partnerships and securities of the managers’ firms or affiliate firms. If the investment vehicle is a commingled account or mutual fund, it is not possible to place restrictions on any aspect of fund management. At December 31, 2012, the current target ranges and actual allocations for Alliant Energy’s, IPL’s and WPL’s defined benefit pension plan assets were as follows:
| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | — | % | - | 5% |  | 4%
Equity securities: |  |  |  |  |
U.S. large cap core | 10 | % | - | 20% |  | 13%
U.S. large cap value | 6 | % | - | 16% |  | 11%
U.S. large cap growth | 6 | % | - | 16% |  | 11%
U.S. small cap value | — | % | - | 6% |  | 3%
U.S. small cap growth | — | % | - | 6% |  | 3%
International - developed markets | 11 | % | - | 23% |  | 16%
International - emerging markets | — | % | - | 8% |  | 4%
Global asset allocation securities | 5 | % | - | 15% |  | 10%
Fixed income securities | 15 | % | - | 35% |  | 25%
Other Postretirement Benefits Plans Assets - Other postretirement benefits plans assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in Voluntary Employees’ Beneficiary Association (VEBA) trusts. The investment policy and strategy of the 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. For VEBA trusts with assets greater than $5 million, the mix among asset classes is controlled by long-term allocation targets. The asset allocation is monitored regularly and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. Prohibited investment vehicles include, but may not be limited to, direct ownership of real estate, margin trading, oil and gas limited partnerships and securities of the managers’ firms or affiliate firms. If the investment vehicle is a commingled account or mutual fund, it is not possible to place restrictions on any aspect of fund management. At December 31, 2012, the current target ranges and actual allocations for Alliant Energy’s, IPL’s and WPL’s VEBA trusts with assets greater than $5 million were as follows:
| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | — | % | - | 5% |  | 2%
Equity securities: |  |  |  |  |
Domestic | 25 | % | - | 45% |  | 34%
International | 10 | % | - | 20% |  | 15%
Global asset allocation securities | 20 | % | - | 40% |  | 29%
Fixed income securities | 10 | % | - | 30% |  | 20%
Securities Lending Program - Alliant Energy, IPL and WPL have a securities lending program with a third-party agent that allows the agent to lend certain securities from their defined benefit pension and other postretirement benefits plans to selected entities against receipt of collateral (in the form of cash, government and agency securities or letters of credit) as provided for and determined in accordance with its securities lending agency agreement. Initial collateral levels are no less than 100% of the market value of loans to non-affiliated borrowers of U.S. government securities; 102% of the market value of loans to affiliated borrowers of U.S. government securities; 102% of the market value of loans on U.S. corporate bonds and U.S. equity securities; 105% of the market value of loans on non-U.S. securities; and 102% of the market value of loans on all other securities. Refer to “Fair Value Measurements” below for details of fair value of invested collateral and amounts due to borrowers for the securities lending program. Fair Value Measurements - The following tables report a framework for measuring fair value. The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value. The three levels of the fair value hierarchy and examples of each are as follows: Level 1 - Pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. Alliant Energy’s, IPL’s and WPL’s investments in equity and fixed income securities held in registered investment companies and directly held equity securities are valued at the closing price reported in the active market in which the securities are traded. Level 2 - Pricing inputs are quoted prices for similar asset or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Alliant Energy’s, IPL’s and WPL’s investments in corporate bonds and government and agency obligations are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Alliant Energy’s, IPL’s and WPL’s investments in equity and fixed income securities in common/collective trusts are valued at the net asset value of shares held by the plans, which is based on the fair market value of the underlying investments in equity and fixed income securities of the common/collective trusts. Level 2 plan assets also consist of asset backed securities within their securities lending invested collateral. Level 3 - Pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. Alliant Energy’s, IPL’s and WPL’s Level 3 plan assets include certain asset backed securities and corporate bonds within their securities lending invested collateral. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while Alliant Energy, IPL and WPL believe their valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date. At December 31, the fair values of Alliant Energy’s qualified and non-qualified defined benefit pension plans assets by asset category and fair value hierarchy level were as follows (in millions):
Alliant Energy | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $43.9 |  |  |  | $— |  |  |  | $43.9 |  |  |  | $— |  |  |  | $117.5 |  |  |  | $117.5 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 129.0 |  |  | 129.0 |  |  | — |  |  | — |  |  | 110.7 |  |  | 110.7 |  |  | — |  |  | — |
U.S. large cap value | 107.9 |  |  | — |  |  | 107.9 |  |  | — |  |  | 91.6 |  |  | — |  |  | 91.6 |  |  | — |
U.S. large cap growth | 105.8 |  |  | — |  |  | 105.8 |  |  | — |  |  | 91.5 |  |  | — |  |  | 91.5 |  |  | — |
U.S. small cap value | 30.4 |  |  | — |  |  | 30.4 |  |  | — |  |  | 25.7 |  |  | — |  |  | 25.7 |  |  | — |
U.S. small cap growth | 25.0 |  |  | 25.0 |  |  | — |  |  | — |  |  | 21.7 |  |  | 21.7 |  |  | — |  |  | — |
International - developed markets | 153.7 |  |  | 80.3 |  |  | 73.4 |  |  | — |  |  | 126.4 |  |  | 65.4 |  |  | 61.0 |  |  | — |
International - emerging markets | 38.5 |  |  | 38.5 |  |  | — |  |  | — |  |  | 30.4 |  |  | 30.4 |  |  | — |  |  | — |
Global asset allocation securities | 94.5 |  |  | 56.3 |  |  | 38.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 30.7 |  |  | — |  |  | 30.7 |  |  | — |  |  | 57.1 |  |  | — |  |  | 57.1 |  |  | — |
Government and agency obligations | 49.2 |  |  | — |  |  | 49.2 |  |  | — |  |  | 87.8 |  |  | — |  |  | 87.8 |  |  | — |
Fixed income funds | 162.6 |  |  | 0.2 |  |  | 162.4 |  |  | — |  |  | 146.7 |  |  | 0.2 |  |  | 146.5 |  |  | — |
Securities lending invested collateral | 4.4 |  |  | — |  |  | 2.9 |  |  | 1.5 |  |  | 9.3 |  |  | 4.7 |  |  | 2.8 |  |  | 1.8 |
| 975.6 |  |  |  | $329.3 |  |  |  | $644.8 |  |  |  | $1.5 |  |  | 916.4 |  |  |  | $350.6 |  |  |  | $564.0 |  |  |  | $1.8 |
Accrued investment income | 0.6 |  |  |  |  |  |  |  |  | 1.0 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (1.5 | ) |  |  |  |  |  |  |  | (4.7 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (9.1 | ) |  |  |  |  |  |  |  | (15.3 | ) |  |  |  |  |  |
Total pension plan assets |  | $965.6 |  |  |  |  |  |  |  |  |  | $897.4 |  |  |  |  |  |  |
At December 31, the fair values of IPL’s and WPL’s qualified and non-qualified defined benefit pension plan assets associated with IPL’s and WPL’s current and former non-bargaining employees who are participants in Alliant Energy and Corporate Services sponsored plans that were directly assigned to IPL and WPL, along with the percentage these assets represent of the fair values by asset category and fair value hierarchy level shown in the above table were as follows (dollars in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2012 |  | 2011
Fair values of directly assigned amounts | $136.5 |  | $127.4 |  | $102.2 |  | $97.0
Percentage represented | 14.1% |  | 14.2% |  | 10.6% |  | 10.8%
At December 31, the fair values of IPL’s qualified defined benefit pension plan assets by asset category and fair value hierarchy level were as follows (in millions):
IPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $14.6 |  |  |  | $— |  |  |  | $14.6 |  |  |  | $— |  |  |  | $39.1 |  |  |  | $39.1 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 43.1 |  |  | 43.1 |  |  | — |  |  | — |  |  | 36.8 |  |  | 36.8 |  |  | — |  |  | — |
U.S. large cap value | 36.0 |  |  | — |  |  | 36.0 |  |  | — |  |  | 30.5 |  |  | — |  |  | 30.5 |  |  | — |
U.S. large cap growth | 35.3 |  |  | — |  |  | 35.3 |  |  | — |  |  | 30.5 |  |  | — |  |  | 30.5 |  |  | — |
U.S. small cap value | 10.2 |  |  | — |  |  | 10.2 |  |  | — |  |  | 8.6 |  |  | — |  |  | 8.6 |  |  | — |
U.S. small cap growth | 8.3 |  |  | 8.3 |  |  | — |  |  | — |  |  | 7.2 |  |  | 7.2 |  |  | — |  |  | — |
International - developed markets | 51.3 |  |  | 26.8 |  |  | 24.5 |  |  | — |  |  | 42.1 |  |  | 21.8 |  |  | 20.3 |  |  | — |
International - emerging markets | 12.9 |  |  | 12.9 |  |  | — |  |  | — |  |  | 10.1 |  |  | 10.1 |  |  | — |  |  | — |
Global asset allocation securities | 31.5 |  |  | 18.8 |  |  | 12.7 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 10.2 |  |  | — |  |  | 10.2 |  |  | — |  |  | 19.0 |  |  | — |  |  | 19.0 |  |  | — |
Government and agency obligations | 16.4 |  |  | — |  |  | 16.4 |  |  | — |  |  | 29.2 |  |  | — |  |  | 29.2 |  |  | — |
Fixed income funds | 54.3 |  |  | 0.1 |  |  | 54.2 |  |  | — |  |  | 48.8 |  |  | 0.1 |  |  | 48.7 |  |  | — |
Securities lending invested collateral | 1.5 |  |  | — |  |  | 1.0 |  |  | 0.5 |  |  | 3.1 |  |  | 1.6 |  |  | 0.9 |  |  | 0.6 |
| 325.6 |  |  |  | $110.0 |  |  |  | $215.1 |  |  |  | $0.5 |  |  | 305.0 |  |  |  | $116.7 |  |  |  | $187.7 |  |  |  | $0.6 |
Accrued investment income | 0.2 |  |  |  |  |  |  |  |  | 0.4 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (0.5 | ) |  |  |  |  |  |  |  | (1.6 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (3.0 | ) |  |  |  |  |  |  |  | (5.1 | ) |  |  |  |  |  |
Total pension plan assets |  | $322.3 |  |  |  |  |  |  |  |  |  | $298.7 |  |  |  |  |  |  |
At December 31, the fair values of WPL’s qualified defined benefit pension plan assets by asset category and fair value hierarchy level were as follows (in millions):
WPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $14.2 |  |  |  | $— |  |  |  | $14.2 |  |  |  | $— |  |  |  | $37.9 |  |  |  | $37.9 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. large cap core | 41.8 |  |  | 41.8 |  |  | — |  |  | — |  |  | 35.7 |  |  | 35.7 |  |  | — |  |  | — |
U.S. large cap value | 35.0 |  |  | — |  |  | 35.0 |  |  | — |  |  | 29.6 |  |  | — |  |  | 29.6 |  |  | — |
U.S. large cap growth | 34.3 |  |  | — |  |  | 34.3 |  |  | — |  |  | 29.5 |  |  | — |  |  | 29.5 |  |  | — |
U.S. small cap value | 9.9 |  |  | — |  |  | 9.9 |  |  | — |  |  | 8.3 |  |  | — |  |  | 8.3 |  |  | — |
U.S. small cap growth | 8.1 |  |  | 8.1 |  |  | — |  |  | — |  |  | 7.0 |  |  | 7.0 |  |  | — |  |  | — |
International - developed markets | 49.9 |  |  | 26.1 |  |  | 23.8 |  |  | — |  |  | 40.8 |  |  | 21.1 |  |  | 19.7 |  |  | — |
International - emerging markets | 12.5 |  |  | 12.5 |  |  | — |  |  | — |  |  | 9.8 |  |  | 9.8 |  |  | — |  |  | — |
Global asset allocation securities | 30.7 |  |  | 18.3 |  |  | 12.4 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 9.9 |  |  | — |  |  | 9.9 |  |  | — |  |  | 18.4 |  |  | — |  |  | 18.4 |  |  | — |
Government and agency obligations | 16.0 |  |  | — |  |  | 16.0 |  |  | — |  |  | 28.3 |  |  | — |  |  | 28.3 |  |  | — |
Fixed income funds | 52.8 |  |  | 0.1 |  |  | 52.7 |  |  | — |  |  | 47.4 |  |  | 0.1 |  |  | 47.3 |  |  | — |
Securities lending invested collateral | 1.4 |  |  | — |  |  | 0.9 |  |  | 0.5 |  |  | 3.0 |  |  | 1.5 |  |  | 0.9 |  |  | 0.6 |
| 316.5 |  |  |  | $106.9 |  |  |  | $209.1 |  |  |  | $0.5 |  |  | 295.7 |  |  |  | $113.1 |  |  |  | $182.0 |  |  |  | $0.6 |
Accrued investment income | 0.2 |  |  |  |  |  |  |  |  | 0.3 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (0.5 | ) |  |  |  |  |  |  |  | (1.5 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (3.0 | ) |  |  |  |  |  |  |  | (4.9 | ) |  |  |  |  |  |
Total pension plan assets |  | $313.2 |  |  |  |  |  |  |  |  |  | $289.6 |  |  |  |  |  |  |
At December 31, the fair values of other postretirement benefits plans assets by asset category and fair value hierarchy level were as follows (in millions):
Alliant Energy | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $8.4 |  |  |  | $— |  |  |  | $8.4 |  |  |  | $— |  |  |  | $14.0 |  |  |  | $14.0 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 32.9 |  |  | 32.9 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 2.8 |  |  | 2.8 |  |  | — |  |  | — |  |  | 37.1 |  |  | 37.1 |  |  | — |  |  | — |
U.S. large cap value | 2.4 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |
U.S. large cap growth | 2.3 |  |  | — |  |  | 2.3 |  |  | — |  |  | 2.4 |  |  | — |  |  | 2.4 |  |  | — |
U.S. mid cap core | — |  |  | — |  |  | — |  |  | — |  |  | 17.8 |  |  | 17.8 |  |  | — |  |  | — |
U.S. small cap core | — |  |  | — |  |  | — |  |  | — |  |  | 4.7 |  |  | 4.7 |  |  | — |  |  | — |
U.S. small cap value | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.6 |  |  | — |  |  | 0.6 |  |  | — |
U.S. small cap growth | 0.6 |  |  | 0.6 |  |  | — |  |  | — |  |  | 0.5 |  |  | 0.5 |  |  | — |  |  | — |
International - blend | 14.3 |  |  | 14.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 3.4 |  |  | 1.8 |  |  | 1.6 |  |  | — |  |  | 3.3 |  |  | 1.7 |  |  | 1.6 |  |  | — |
International - emerging markets | 0.8 |  |  | 0.8 |  |  | — |  |  | — |  |  | 0.8 |  |  | 0.8 |  |  | — |  |  | — |
Global asset allocation securities | 30.4 |  |  | 29.6 |  |  | 0.8 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 6.1 |  |  | — |  |  | 6.1 |  |  | — |
Government and agency obligations | 1.1 |  |  | — |  |  | 1.1 |  |  | — |  |  | 5.6 |  |  | — |  |  | 5.6 |  |  | — |
Fixed income funds | 22.4 |  |  | 18.8 |  |  | 3.6 |  |  | — |  |  | 25.4 |  |  | 21.6 |  |  | 3.8 |  |  | — |
Securities lending invested collateral | 0.1 |  |  | — |  |  | 0.1 |  |  | — |  |  | 0.4 |  |  | 0.2 |  |  | 0.1 |  |  | 0.1 |
| 123.3 |  |  |  | $101.6 |  |  |  | $21.7 |  |  |  | $— |  |  | 121.1 |  |  |  | $98.4 |  |  |  | $22.6 |  |  |  | $0.1 |
Accrued investment income | — |  |  |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | — |  |  |  |  |  |  |  |  | (0.2 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (0.2 | ) |  |  |  |  |  |  |  | (0.6 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $123.1 |  |  |  |  |  |  |  |  |  | $120.4 |  |  |  |  |  |  |
IPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $3.3 |  |  |  | $— |  |  |  | $3.3 |  |  |  | $— |  |  |  | $2.1 |  |  |  | $2.1 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 24.3 |  |  | 24.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 0.8 |  |  | 0.8 |  |  | — |  |  | — |  |  | 29.3 |  |  | 29.3 |  |  | — |  |  | — |
U.S. large cap value | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.8 |  |  | — |  |  | 0.8 |  |  | — |
U.S. large cap growth | 0.7 |  |  | — |  |  | 0.7 |  |  | — |  |  | 0.8 |  |  | — |  |  | 0.8 |  |  | — |
U.S. mid cap core | — |  |  | — |  |  | — |  |  | — |  |  | 14.7 |  |  | 14.7 |  |  | — |  |  | — |
U.S. small cap value | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 0.2 |  |  | — |
U.S. small cap growth | 0.2 |  |  | 0.2 |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.2 |  |  | — |  |  | — |
International - blend | 10.6 |  |  | 10.6 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 1.0 |  |  | 0.5 |  |  | 0.5 |  |  | — |  |  | 1.2 |  |  | 0.6 |  |  | 0.6 |  |  | — |
International - emerging markets | 0.2 |  |  | 0.2 |  |  | — |  |  | — |  |  | 0.3 |  |  | 0.3 |  |  | — |  |  | — |
Global asset allocation securities | 21.5 |  |  | 21.3 |  |  | 0.2 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.2 |  |  | — |  |  | 0.2 |  |  | — |  |  | 4.6 |  |  | — |  |  | 4.6 |  |  | — |
Government and agency obligations | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 4.1 |  |  | — |  |  | 4.1 |  |  | — |
Fixed income funds | 14.9 |  |  | 13.9 |  |  | 1.0 |  |  | — |  |  | 16.5 |  |  | 15.1 |  |  | 1.4 |  |  | — |
Securities lending invested collateral | — |  |  | — |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.1 |  |  | 0.1 |  |  | — |
| 78.9 |  |  |  | $71.8 |  |  |  | $7.1 |  |  |  | $— |  |  | 75.0 |  |  |  | $62.4 |  |  |  | $12.6 |  |  |  | $— |
Accrued investment income | — |  |  |  |  |  |  |  |  | 0.1 |  |  |  |  |  |  |
Due to borrowers for securities lending program | (0.1 | ) |  |  |  |  |  |  |  | (0.4 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $78.8 |  |  |  |  |  |  |  |  |  | $74.7 |  |  |  |  |  |  |
WPL | 2012 |  | 2011
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
| Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents |  | $3.9 |  |  |  | $— |  |  |  | $3.9 |  |  |  | $— |  |  |  | $10.5 |  |  |  | $10.5 |  |  |  | $— |  |  |  | $— |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. blend | 3.1 |  |  | 3.1 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
U.S. large cap core | 1.3 |  |  | 1.3 |  |  | — |  |  | — |  |  | 1.2 |  |  | 1.2 |  |  | — |  |  | — |
U.S. large cap value | 1.2 |  |  | — |  |  | 1.2 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
U.S. large cap growth | 1.1 |  |  | — |  |  | 1.1 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
U.S. small cap core | — |  |  | — |  |  | — |  |  | — |  |  | 4.7 |  |  | 4.7 |  |  | — |  |  | — |
U.S. small cap value | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 0.3 |  |  | — |
U.S. small cap growth | 0.3 |  |  | 0.3 |  |  | — |  |  | — |  |  | 0.2 |  |  | 0.2 |  |  | — |  |  | — |
International - blend | 1.3 |  |  | 1.3 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
International - developed markets | 1.6 |  |  | 0.8 |  |  | 0.8 |  |  | — |  |  | 1.3 |  |  | 0.7 |  |  | 0.6 |  |  | — |
International - emerging markets | 0.4 |  |  | 0.4 |  |  | — |  |  | — |  |  | 0.3 |  |  | 0.3 |  |  | — |  |  | — |
Global asset allocation securities | 3.6 |  |  | 3.2 |  |  | 0.4 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | 0.3 |  |  | — |  |  | 0.3 |  |  | — |  |  | 1.1 |  |  | — |  |  | 1.1 |  |  | — |
Government and agency obligations | 0.5 |  |  | — |  |  | 0.5 |  |  | — |  |  | 1.0 |  |  | — |  |  | 1.0 |  |  | — |
Fixed income funds | 3.5 |  |  | 1.8 |  |  | 1.7 |  |  | — |  |  | 2.6 |  |  | 1.0 |  |  | 1.6 |  |  | — |
Securities lending invested collateral | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |  |  | 0.1 |  |  | — |  |  | — |
| 22.4 |  |  |  | $12.2 |  |  |  | $10.2 |  |  |  | $— |  |  | 25.3 |  |  |  | $18.7 |  |  |  | $6.6 |  |  |  | $— |
Due to brokers, net (pending trades with brokers) | — |  |  |  |  |  |  |  |  | (0.1 | ) |  |  |  |  |  |
Due to borrowers for securities lending program | (0.1 | ) |  |  |  |  |  |  |  | (0.1 | ) |  |  |  |  |  |
Total other postretirement benefits plan assets |  | $22.3 |  |  |  |  |  |  |  |  |  | $25.1 |  |  |  |  |  |  |
For the various defined benefit pension and other postretirement benefits plans, Alliant Energy common stock represented less than 1% of total plan assets at December 31, 2012 and 2011. Cash Balance Plan - Alliant Energy’s defined benefit pension plans include the Cash Balance Plan that provides benefits for certain non-bargaining unit employees. The Cash Balance Plan has been closed to new hires since 2005. Effective 2008, Alliant Energy amended the Cash Balance Plan by discontinuing additional contributions into employees’ Cash Balance Plan accounts and increased its level of contributions to its 401(k) Savings Plan. In 2009, Alliant Energy amended the Cash Balance Plan by changing participants’ future interest credit formula to use the annual change in the consumer price index. This amendment provides participants an interest crediting rate that is 3% more than the annual change in the consumer price index. Refer to Note 13(c) for discussion of a class-action lawsuit filed against the Cash Balance Plan in 2008 and an agreement Alliant Energy reached with the IRS, which resulted in a favorable determination letter for the Cash Balance Plan in 2011. 401(k) Savings Plans - A significant number of Alliant Energy, IPL and WPL employees participate in defined contribution retirement plans (401(k) savings plans). Alliant Energy common stock represented 12.5% and 14.6% of total assets held in 401(k) savings plans at December 31, 2012 and 2011, respectively. Costs related to the 401(k) savings plans, which are partially based on the participants’ level of contribution, were as follows (in millions):
| Alliant Energy |  | IPL (a) |  | WPL (a)
| 2012 |  | 2011 |  | 2010 |  | 2012 |  |  | 2011 |  |  | 2010 |  |  | 2012 |  | 2011 |  | 2010
401(k) costs |  | $18.5 |  |  |  | $18.4 |  |  |  | $18.5 |  |  |  | $9.6 |  |  |  | $9.2 |  |  |  | $8.8 |  |  |  | $8.1 |  |  |  | $8.4 |  |  |  | $8.9 |
(a) | IPL’s and WPL’s amounts include allocated costs associated with Corporate Services employees.
(b) Equity-based Compensation Plans - In 2010, Alliant Energy’s shareowners approved the Alliant Energy 2010 Omnibus Incentive Plan (OIP), which permits the grant of stock options, restricted stock, restricted stock units, performance shares, performance units, and other stock-based awards and performance-based cash awards to key employees. At December 31, 2012, performance shares and restricted stock were outstanding and 4.2 million shares of Alliant Energy’s common stock remained available for grants under the OIP. Upon shareowner approval of the OIP, the Alliant Energy 2002 Equity Incentive Plan (EIP) terminated resulting in no new awards authorized to be granted under the EIP. All awards previously granted under the EIP that are still outstanding remain valid and continue to be subject to all of the terms and conditions of the EIP. At December 31, 2012, non-qualified stock options, restricted stock and performance shares were outstanding under the EIP and another predecessor plan under which new awards can no longer be granted. Alliant Energy satisfies payouts related to equity awards under the OIP and EIP through the issuance of new shares of its common stock. Alliant Energy also has the Alliant Energy Director Long Term Incentive Plan (DLIP), which permits the grant of long-term performance-based awards, including performance units and restricted cash awards to certain key employees. At December 31, 2012, performance units and performance contingent cash awards were outstanding under the DLIP. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash. A summary of compensation expense (allocated to IPL and WPL) and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Compensation expense |  | $6.9 |  |  |  | $10.1 |  |  |  | $7.5 |  |  |  | $3.6 |  |  |  | $5.5 |  |  |  | $4.0 |  |  |  | $3.0 |  |  |  | $4.1 |  |  |  | $3.0 |
Income tax benefits | 2.8 |  |  | 4.0 |  |  | 3.0 |  |  | 1.5 |  |  | 2.2 |  |  | 1.6 |  |  | 1.2 |  |  | 1.7 |  |  | 1.2 |
As of December 31, 2012, total unrecognized compensation cost related to share-based compensation awards was $6.1 million, which is expected to be recognized over a weighted average period of between 1 and 2 years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is primarily recorded in “Utility - Other operation and maintenance” in the Consolidated Statements of Income. Performance Shares and Units - Payouts of performance shares and units to key employees are contingent upon achievement over 3-year periods of specified performance criteria, which currently include metrics of total shareowner return relative to investor-owned utility peer groups. Payouts of nonvested performance shares and units issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of these performance shares and units to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Payouts of nonvested performance shares and units issued prior to 2012 are prorated at retirement, death, disability or involuntary termination without cause based on time worked during the full or entire performance period and achievement of the performance criteria. Participants’ nonvested performance shares and units are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Nonvested performance shares and units do not have non-forfeitable rights to dividends when dividends are paid to common shareowners. Alliant Energy assumes it will make future payouts of its performance shares and units in cash; therefore, performance shares and units are accounted for as liability awards. Performance Shares - Performance shares can be paid out in shares of Alliant Energy’s common stock, cash or a combination of cash and stock and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance shares activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares (a) |  | Shares (a) |  | Shares (a)
Nonvested shares, January 1 | 236,979 |  |  | 234,518 |  |  | 256,579 |
Granted | 45,612 |  |  | 64,217 |  |  | 72,487 |
Vested (b) | (111,980 | ) |  | (57,838 | ) |  | — |
Forfeited (c) | (25,334 | ) |  | (3,918 | ) |  | (94,548 | )
Nonvested shares, December 31 | 145,277 |  |  | 236,979 |  |  | 234,518 |
(a) | Share amounts represent the target number of performance shares. Each performance share’s value is based on the price of one share of Alliant Energy’s common stock at the end of the performance period. The actual number of shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares.
(b) | In 2012, 111,980 performance shares granted in 2009 vested at 162.5% of the target, resulting in payouts valued at $8.0 million, which consisted of a combination of cash and common stock (6,399 shares). In 2011, 57,838 performance shares granted in 2008 vested at 75% of the target, resulting in payouts valued at $1.6 million, which consisted of a combination of cash and common stock (1,387 shares).
(c) | In 2010, 57,100 performance shares granted in 2007 were forfeited without payout because the specified performance criteria for such shares were not met. The remaining forfeitures during 2012, 2011 and 2010 were primarily caused by retirements and voluntary terminations of participants.
Performance Units - Performance units must be paid out in cash and are adjusted by a performance multiplier, which ranges from zero to 200% based on the performance criteria. A summary of the performance unit activity was as follows:
| 2012 |  | 2011 |  | 2010
| Units (a) |  | Units (a) |  | Units (a)
Nonvested units, January 1 | 42,996 |  |  | 23,128 |  |  | — |
Granted | 24,686 |  |  | 23,975 |  |  | 23,795 |
Forfeited | (2,713 | ) |  | (4,107 | ) |  | (667 | )
Nonvested units, December 31 | 64,969 |  |  | 42,996 |  |  | 23,128 |
(a) | Unit amounts represent the target number of performance units. Each performance unit’s value is based on the average price of one share of Alliant Energy’s common stock on the grant date of the award. The actual payout for performance units is dependent upon actual performance and may range from zero to 200% of the target number of units.
Fair Value of Awards - Information related to fair values of nonvested performance shares and units at December 31, 2012, by year of grant, were as follows:
| Performance Shares |  | Performance Units
| 2012 Grant |  | 2011 Grant |  | 2010 Grant |  | 2012 Grant |  | 2011 Grant |  | 2010 Grant
Nonvested awards | 45,612 |  |  | 45,235 |  |  | 54,430 |  |  | 23,969 |  |  | 21,095 |  |  | 19,905 |
Alliant Energy common stock closing price on December 31, 2012 |  | $43.91 |  |  |  | $43.91 |  |  |  | $43.91 |  |  |  |  |  |  |
Alliant Energy common stock average price on grant date |  |  |  |  |  |  |  | $43.05 |  |  |  | $38.75 |  |  |  | $32.56 |
Estimated payout percentage based on performance criteria | 89 | % |  | 107 | % |  | 198 | % |  | 89 | % |  | 107 | % |  | 198 | %
Fair values of each nonvested award |  | $39.08 |  |  |  | $46.98 |  |  |  | $86.72 |  |  |  | $38.31 |  |  |  | $41.46 |  |  |  | $64.30 |
At December 31, 2012, fair values of nonvested performance shares and units were calculated using a Monte Carlo simulation to determine the anticipated total shareowner returns of Alliant Energy and its investor-owned utility peer groups. Expected volatility was based on historical volatilities using daily stock prices over the past three years. Expected dividend yields were calculated based on the most recent quarterly dividend rates announced prior to the measurement date and stock prices at the measurement date. The risk-free interest rate was based on the three-year U.S. Treasury rate in effect as of the measurement date. Restricted Stock - Restricted stock consists of time-based and performance-contingent restricted stock. Time-based Restricted Stock - The current restriction period for outstanding time-based restricted stock is up to three years. Nonvested shares of time-based restricted stock generally become vested upon retirement. Compensation costs related to awards granted to retirement-eligible employees are generally expensed on the date of grant. Participants’ nonvested time-based restricted stock issued prior to 2012 is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Participants’ nonvested time-based restricted stock issued prior to 2012 is fully vested in the event of retirement, death, disability or involuntary termination without cause. The fair value of time-based restricted stock is based on the average market price at the grant date. A summary of the time-based restricted stock activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value
Nonvested shares, January 1 | 35,800 |  |  |  | $30.87 |  |  | 70,033 |  |  |  | $32.27 |  |  | 125,349 |  |  |  | $32.47 |
Granted | — |  |  | — |  |  | 5,000 |  |  | 39.86 |  |  | — |  |  | — |
Vested | (32,466 | ) |  | 29.95 |  |  | (38,633 | ) |  | 34.60 |  |  | (54,016 | ) |  | 32.72 |
Forfeited | — |  |  | — |  |  | (600 | ) |  | 29.41 |  |  | (1,300 | ) |  | 32.78 |
Nonvested shares, December 31 | 3,334 |  |  | 39.86 |  |  | 35,800 |  |  | 30.87 |  |  | 70,033 |  |  | 32.27 |
Performance-contingent Restricted Stock - Vesting of performance-contingent restricted stock grants are based on the achievement of certain performance targets (currently specified earnings growth). The performance metric for the 2012, 2011 and 2010 grants is consolidated net income growth. If performance targets are not met within the performance period, which currently ranges from two to four years, these restricted stock grants are forfeited. Payouts of nonvested performance-contingent restricted stock issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of this performance-contingent restricted stock to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Nonvested shares of performance-contingent restricted stock issued prior to 2012 are prorated at retirement based on time worked during the full or entire performance period and vest only if and when the performance criteria are met. Participants’ nonvested performance-contingent restricted stock is forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. The fair value of performance-contingent restricted stock is based on the average market price at the grant date. A summary of the performance-contingent restricted stock activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value |  | Shares |  | Weighted Average Fair Value
Nonvested shares, January 1 | 301,738 |  |  |  | $32.60 |  |  | 296,190 |  |  |  | $32.32 |  |  | 226,007 |  |  |  | $32.25 |
Granted | 45,612 |  |  | 43.05 |  |  | 64,217 |  |  | 38.75 |  |  | 72,487 |  |  | 32.56 |
Vested (a) | (65,172 | ) |  | 32.56 |  |  | (53,274 | ) |  | 37.93 |  |  | — |  |  | — |
Forfeited (b) | (70,527 | ) |  | 39.93 |  |  | (5,395 | ) |  | 38.00 |  |  | (2,304 | ) |  | 32.56 |
Nonvested shares, December 31 | 211,651 |  |  | 32.42 |  |  | 301,738 |  |  | 32.60 |  |  | 296,190 |  |  | 32.32 |
(a) | In 2012 and 2011, 65,172 and 53,274 performance-contingent restricted shares granted in 2010 and 2007, respectively, vested because the specified performance criteria for such shares were met.
(b) | In 2012, 65,516 performance-contingent restricted shares granted in 2008 were forfeited because the specified performance criteria for such shares were not met. The remaining forfeitures during 2012, 2011 and 2010 were primarily caused by retirements and terminations of participants.
Non-qualified Stock Options - Options were granted at the market price of the shares on the date of grant, vested over three years and expire no later than 10 years after the grant date. Alliant Energy has not granted any options since 2004. A summary of the stock option activity was as follows:
| 2012 |  | 2011 |  | 2010
| Shares |  | Weighted Average Exercise Price |  | Shares |  | Weighted Average Exercise Price |  | Shares |  | Weighted Average Exercise Price
Outstanding, January 1 | 63,889 |  |  |  | $24.21 |  |  | 163,680 |  |  |  | $24.51 |  |  | 384,331 |  |  |  | $27.02 |
Exercised | (38,711 | ) |  | 24.41 |  |  | (99,791 | ) |  | 24.71 |  |  | (191,433 | ) |  | 28.93 |
Expired | — |  |  | — |  |  | — |  |  | — |  |  | (29,218 | ) |  | 28.59 |
Outstanding and exercisable, December 31 | 25,178 |  |  | 23.89 |  |  | 63,889 |  |  | 24.21 |  |  | 163,680 |  |  | 24.51 |
The weighted average remaining contractual term for options outstanding and exercisable at December 31, 2012 was 1 year. The aggregate intrinsic value of options outstanding and exercisable at December 31, 2012 was $0.5 million. Other information related to stock option activity was as follows (in millions):
| 2012 |  | 2011 |  | 2010
Cash received from stock options exercised |  | $0.9 |  |  |  | $2.5 |  |  |  | $5.5 |
Aggregate intrinsic value of stock options exercised | 0.8 |  |  | 1.6 |  |  | 1.1 |
Income tax benefit from the exercise of stock options | 0.3 |  |  | 0.7 |  |  | 0.4 |
Performance Contingent Cash Awards - Performance contingent cash award payouts to key employees are based on the achievement of certain performance targets (currently specified consolidated net income growth). If performance targets are not met within the performance period, which currently ranges from two to four years, there are no payouts for these awards. Payouts of nonvested awards issued in 2012 are prorated at retirement, death or disability based on time worked during the first year of the performance period and achievement of the performance criteria. Upon achievement of the performance criteria, payouts of these 2012 awards to participants who terminate employment after the first year of the performance period due to retirement, death or disability are not prorated. Nonvested awards issued prior to 2012 are prorated at retirement based on time worked during the full or entire performance period and achievement of the performance criteria. Participants’ nonvested awards are forfeited if the participant voluntarily leaves Alliant Energy or is terminated for cause. Each performance contingent cash award’s value is based on the price of one share of Alliant Energy’s common stock at the end of the performance period. Alliant Energy accounts for performance contingent cash awards as liability awards because payouts will be made in the form of cash. A summary of the performance contingent cash awards activity was as follows:
| 2012 |  | 2011 |  | 2010
| Awards |  | Awards |  | Awards
Nonvested awards, January 1 | 46,676 |  |  | 23,428 |  |  | — |
Granted | 36,936 |  |  | 23,975 |  |  | 23,795 |
Vested (a) | (21,605 | ) |  | — |  |  | — |
Forfeited | (2,368 | ) |  | (727 | ) |  | (367 | )
Nonvested awards, December 31 | 59,639 |  |  | 46,676 |  |  | 23,428 |
(a) | In 2012, 21,605 performance contingent cash awards granted in 2010 vested, resulting in cash payouts valued at $0.9 million.

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