|
Summary Of Significant Accounting Policies (Tables)
|
12 Months Ended |
|
Dec. 31, 2012
|
| Regulatory Assets |
Regulatory Assets - At December 31, regulatory assets were comprised of the following items (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Tax-related |
| $770.7 |
| |
| $634.7 |
| |
| $746.2 |
| |
| $614.6 |
| |
| $24.5 |
| |
| $20.1 |
| Pension and other postretirement benefits costs | 549.2 |
| | 514.1 |
| | 279.3 |
| | 264.9 |
| | 269.9 |
| | 249.2 |
| Asset retirement obligations (AROs) | 62.4 |
| | 65.9 |
| | 38.6 |
| | 48.7 |
| | 23.8 |
| | 17.2 |
| Derivatives | 40.2 |
| | 77.7 |
| | 16.3 |
| | 33.5 |
| | 23.9 |
| | 44.2 |
| Environmental-related costs | 34.9 |
| | 38.9 |
| | 30.3 |
| | 32.2 |
| | 4.6 |
| | 6.7 |
| Emission allowances | 30.0 |
| | 30.0 |
| | 30.0 |
| | 30.0 |
| | — |
| | — |
| Debt redemption costs | 19.8 |
| | 21.8 |
| | 13.6 |
| | 15.1 |
| | 6.2 |
| | 6.7 |
| Proposed clean air compliance projects costs | 16.7 |
| | 14.9 |
| | 7.8 |
| | 6.9 |
| | 8.9 |
| | 8.0 |
| IPL’s electric transmission service costs | 16.6 |
| | 24.9 |
| | 16.6 |
| | 24.9 |
| | — |
| | — |
| Proposed coal-fired base-load projects costs | 14.2 |
| | 21.5 |
| | 10.1 |
| | 15.3 |
| | 4.1 |
| | 6.2 |
| Other | 57.7 |
| | 50.6 |
| | 29.1 |
| | 31.2 |
| | 28.6 |
| | 19.4 |
| |
| $1,612.4 |
| |
| $1,495.0 |
| |
| $1,217.9 |
| |
| $1,117.3 |
| |
| $394.5 |
| |
| $377.7 |
|
|
| Regulatory Liabilities |
Regulatory Liabilities - At December 31, regulatory liabilities were comprised of the following items (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Cost of removal obligations |
| $408.7 |
| |
| $404.9 |
| |
| $268.0 |
| |
| $261.9 |
| |
| $140.7 |
| |
| $143.0 |
| IPL’s tax benefit riders | 355.8 |
| | 349.6 |
| | 355.8 |
| | 349.6 |
| | — |
| | — |
| Energy conservation cost recovery | 55.1 |
| | 29.6 |
| | 10.0 |
| | 4.7 |
| | 45.1 |
| | 24.9 |
| IPL’s electric transmission assets sale | 32.5 |
| | 45.1 |
| | 32.5 |
| | 45.1 |
| | — |
| | — |
| Commodity cost recovery | 17.7 |
| | 23.8 |
| | 5.2 |
| | 23.2 |
| | 12.5 |
| | 0.6 |
| IPL’s DAEC sale | 9.5 |
| | 14.6 |
| | 9.5 |
| | 14.6 |
| | — |
| | — |
| Other | 36.8 |
| | 42.5 |
| | 20.4 |
| | 22.2 |
| | 16.4 |
| | 20.3 |
| |
| $916.1 |
| |
| $910.1 |
| |
| $701.4 |
| |
| $721.3 |
| |
| $214.7 |
| |
| $188.8 |
|
|
| Schedule of Electric Plant in Service |
Electric Plant In Service - Electric plant in service by functional category at December 31 was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Generation |
| $4,798.9 |
| |
| $4,100.6 |
| |
| $2,393.0 |
| |
| $2,392.3 |
| |
| $2,405.9 |
| |
| $1,708.3 |
| Distribution | 3,981.5 |
| | 3,782.1 |
| | 2,205.9 |
| | 2,074.8 |
| | 1,775.6 |
| | 1,707.3 |
| Other | 290.3 |
| | 282.7 |
| | 216.3 |
| | 216.9 |
| | 74.0 |
| | 65.8 |
| |
| $9,070.7 |
| |
| $8,165.4 |
| |
| $4,815.2 |
| |
| $4,684.0 |
| |
| $4,255.5 |
| |
| $3,481.4 |
|
|
| Schedule of Average Rates of Depreciation |
The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows: | | | | | | | | | | | | | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Electric - generation | 3.7% | | 3.5% | | 3.7% | | 3.2% | | 3.3% | | 2.9% | Electric - distribution | 2.5% | | 2.4% | | 2.7% | | 2.9% | | 2.9% | | 2.6% | Gas | 3.4% | | 3.5% | | 3.3% | | 2.6% | | 2.6% | | 2.2% | Other | 4.5% | | 4.8% | | 4.9% | | 5.3% | | 5.2% | | 6.5% |
|
| Schedule of Allowance for Funds Used During Construction |
The amount of AFUDC generated by equity and debt components was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Equity |
| $14.1 |
| |
| $7.6 |
| |
| $11.2 |
| |
| $5.2 |
| |
| $3.5 |
| |
| $3.0 |
| |
| $8.9 |
| |
| $4.1 |
| |
| $8.2 |
| Debt | 7.8 |
| | 4.4 |
| | 6.8 |
| | 3.2 |
| | 2.3 |
| | 2.5 |
| | 4.6 |
| | 2.1 |
| | 4.3 |
| |
| $21.9 |
| |
| $12.0 |
| |
| $18.0 |
| |
| $8.4 |
| |
| $5.8 |
| |
| $5.5 |
| |
| $13.5 |
| |
| $6.2 |
| |
| $12.5 |
|
|
| Schedule of Allowance for Funds Used During Construction Recovery Rate |
The AFUDC recovery rates, computed in accordance with the prescribed regulatory formula, were as follows: | | | | | | | | 2012 | | 2011 | | 2010 | IPL (FERC formula) | 8.2% | | 8.5% | | 4.8% | WPL (PSCW formula - retail jurisdiction) (a) | 8.8% | | 8.8% | | 8.8% | WPL (FERC formula - wholesale jurisdiction) | 7.9% | | 6.2% | | 7.2% |
| | (a) | Consistent with the PSCW’s retail rate case order issued in 2009, WPL earned a current return on 50% of the estimated CWIP related to its Bent Tree - Phase I wind project for 2010 and accrued AFUDC on the remaining 50% in 2010. Consistent with the PSCW’s retail order issued in 2009, WPL accrued AFUDC on 100% of CWIP related to the Edgewater Unit 5 emission controls project and the Columbia Units 1 and 2 emission controls project in 2012, 2011 and 2010. Consistent with the PSCW’s retail rate case order issued in 2012, WPL will earn a return on 50% of the estimated CWIP related to its Columbia Units 1 and 2 emission controls project for 2013 and will accrue AFUDC on the remaining 50% in 2013. |
|
| Schedule of Emission Allowance Amortization Expenses |
Amortization of emission allowances is based upon a weighted average cost for each category of vintage year utilized during the reporting period and is recorded in “Electric production fuel and energy purchases” in the Consolidated Statements of Income as follows (in millions): | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Amortization expense | $— | | $13.4 | | $16.5 | | $— | | $12.9 | | $13.1 | | $— | | $0.5 | | $3.4 |
|
| Schedule of Allowance for Doubtful Accounts |
Allowance for doubtful accounts at December 31 was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Customer (a) |
| $1.3 |
| |
| $1.6 |
| |
| $— |
| |
| $— |
| |
| $1.3 |
| |
| $1.6 |
| Other | 2.7 |
| | 2.6 |
| | 0.7 |
| | 0.9 |
| | 0.5 |
| | 0.3 |
| |
| $4.0 |
| |
| $4.2 |
| |
| $0.7 |
| |
| $0.9 |
| |
| $1.8 |
| |
| $1.9 |
|
| | (a) | Refer to Note 4(a) for discussion of IPL’s sales of accounts receivable program. |
|
|
Riverside Energy Center [Member]
|
|
| Carrying Value of Assets Purchased |
As of the closing date, the carrying values of the assets purchased were as follows (in millions): | | | | | Electric plant in service |
| $512.7 |
| Accumulated depreciation | (121.4 | ) | Current assets | 4.2 |
| Other assets | 8.0 |
| |
| $403.5 |
|
|
|
IPL [Member]
|
|
| Regulatory Assets |
Regulatory Assets - At December 31, regulatory assets were comprised of the following items (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Tax-related |
| $770.7 |
| |
| $634.7 |
| |
| $746.2 |
| |
| $614.6 |
| |
| $24.5 |
| |
| $20.1 |
| Pension and other postretirement benefits costs | 549.2 |
| | 514.1 |
| | 279.3 |
| | 264.9 |
| | 269.9 |
| | 249.2 |
| Asset retirement obligations (AROs) | 62.4 |
| | 65.9 |
| | 38.6 |
| | 48.7 |
| | 23.8 |
| | 17.2 |
| Derivatives | 40.2 |
| | 77.7 |
| | 16.3 |
| | 33.5 |
| | 23.9 |
| | 44.2 |
| Environmental-related costs | 34.9 |
| | 38.9 |
| | 30.3 |
| | 32.2 |
| | 4.6 |
| | 6.7 |
| Emission allowances | 30.0 |
| | 30.0 |
| | 30.0 |
| | 30.0 |
| | — |
| | — |
| Debt redemption costs | 19.8 |
| | 21.8 |
| | 13.6 |
| | 15.1 |
| | 6.2 |
| | 6.7 |
| Proposed clean air compliance projects costs | 16.7 |
| | 14.9 |
| | 7.8 |
| | 6.9 |
| | 8.9 |
| | 8.0 |
| IPL’s electric transmission service costs | 16.6 |
| | 24.9 |
| | 16.6 |
| | 24.9 |
| | — |
| | — |
| Proposed coal-fired base-load projects costs | 14.2 |
| | 21.5 |
| | 10.1 |
| | 15.3 |
| | 4.1 |
| | 6.2 |
| Other | 57.7 |
| | 50.6 |
| | 29.1 |
| | 31.2 |
| | 28.6 |
| | 19.4 |
| |
| $1,612.4 |
| |
| $1,495.0 |
| |
| $1,217.9 |
| |
| $1,117.3 |
| |
| $394.5 |
| |
| $377.7 |
|
|
| Regulatory Liabilities |
Regulatory Liabilities - At December 31, regulatory liabilities were comprised of the following items (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Cost of removal obligations |
| $408.7 |
| |
| $404.9 |
| |
| $268.0 |
| |
| $261.9 |
| |
| $140.7 |
| |
| $143.0 |
| IPL’s tax benefit riders | 355.8 |
| | 349.6 |
| | 355.8 |
| | 349.6 |
| | — |
| | — |
| Energy conservation cost recovery | 55.1 |
| | 29.6 |
| | 10.0 |
| | 4.7 |
| | 45.1 |
| | 24.9 |
| IPL’s electric transmission assets sale | 32.5 |
| | 45.1 |
| | 32.5 |
| | 45.1 |
| | — |
| | — |
| Commodity cost recovery | 17.7 |
| | 23.8 |
| | 5.2 |
| | 23.2 |
| | 12.5 |
| | 0.6 |
| IPL’s DAEC sale | 9.5 |
| | 14.6 |
| | 9.5 |
| | 14.6 |
| | — |
| | — |
| Other | 36.8 |
| | 42.5 |
| | 20.4 |
| | 22.2 |
| | 16.4 |
| | 20.3 |
| |
| $916.1 |
| |
| $910.1 |
| |
| $701.4 |
| |
| $721.3 |
| |
| $214.7 |
| |
| $188.8 |
|
|
| Schedule of Electric Plant in Service |
Electric Plant In Service - Electric plant in service by functional category at December 31 was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Generation |
| $4,798.9 |
| |
| $4,100.6 |
| |
| $2,393.0 |
| |
| $2,392.3 |
| |
| $2,405.9 |
| |
| $1,708.3 |
| Distribution | 3,981.5 |
| | 3,782.1 |
| | 2,205.9 |
| | 2,074.8 |
| | 1,775.6 |
| | 1,707.3 |
| Other | 290.3 |
| | 282.7 |
| | 216.3 |
| | 216.9 |
| | 74.0 |
| | 65.8 |
| |
| $9,070.7 |
| |
| $8,165.4 |
| |
| $4,815.2 |
| |
| $4,684.0 |
| |
| $4,255.5 |
| |
| $3,481.4 |
|
|
| Schedule of Average Rates of Depreciation |
The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows: | | | | | | | | | | | | | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Electric - generation | 3.7% | | 3.5% | | 3.7% | | 3.2% | | 3.3% | | 2.9% | Electric - distribution | 2.5% | | 2.4% | | 2.7% | | 2.9% | | 2.9% | | 2.6% | Gas | 3.4% | | 3.5% | | 3.3% | | 2.6% | | 2.6% | | 2.2% | Other | 4.5% | | 4.8% | | 4.9% | | 5.3% | | 5.2% | | 6.5% |
|
| Schedule of Allowance for Funds Used During Construction |
The amount of AFUDC generated by equity and debt components was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Equity |
| $14.1 |
| |
| $7.6 |
| |
| $11.2 |
| |
| $5.2 |
| |
| $3.5 |
| |
| $3.0 |
| |
| $8.9 |
| |
| $4.1 |
| |
| $8.2 |
| Debt | 7.8 |
| | 4.4 |
| | 6.8 |
| | 3.2 |
| | 2.3 |
| | 2.5 |
| | 4.6 |
| | 2.1 |
| | 4.3 |
| |
| $21.9 |
| |
| $12.0 |
| |
| $18.0 |
| |
| $8.4 |
| |
| $5.8 |
| |
| $5.5 |
| |
| $13.5 |
| |
| $6.2 |
| |
| $12.5 |
|
|
| Schedule of Allowance for Funds Used During Construction Recovery Rate |
The AFUDC recovery rates, computed in accordance with the prescribed regulatory formula, were as follows: | | | | | | | | 2012 | | 2011 | | 2010 | IPL (FERC formula) | 8.2% | | 8.5% | | 4.8% | WPL (PSCW formula - retail jurisdiction) (a) | 8.8% | | 8.8% | | 8.8% | WPL (FERC formula - wholesale jurisdiction) | 7.9% | | 6.2% | | 7.2% |
| | (a) | Consistent with the PSCW’s retail rate case order issued in 2009, WPL earned a current return on 50% of the estimated CWIP related to its Bent Tree - Phase I wind project for 2010 and accrued AFUDC on the remaining 50% in 2010. Consistent with the PSCW’s retail order issued in 2009, WPL accrued AFUDC on 100% of CWIP related to the Edgewater Unit 5 emission controls project and the Columbia Units 1 and 2 emission controls project in 2012, 2011 and 2010. Consistent with the PSCW’s retail rate case order issued in 2012, WPL will earn a return on 50% of the estimated CWIP related to its Columbia Units 1 and 2 emission controls project for 2013 and will accrue AFUDC on the remaining 50% in 2013. |
|
| Schedule of Emission Allowance Amortization Expenses |
Amortization of emission allowances is based upon a weighted average cost for each category of vintage year utilized during the reporting period and is recorded in “Electric production fuel and energy purchases” in the Consolidated Statements of Income as follows (in millions): | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Amortization expense | $— | | $13.4 | | $16.5 | | $— | | $12.9 | | $13.1 | | $— | | $0.5 | | $3.4 |
|
| Schedule of Allowance for Doubtful Accounts |
Allowance for doubtful accounts at December 31 was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Customer (a) |
| $1.3 |
| |
| $1.6 |
| |
| $— |
| |
| $— |
| |
| $1.3 |
| |
| $1.6 |
| Other | 2.7 |
| | 2.6 |
| | 0.7 |
| | 0.9 |
| | 0.5 |
| | 0.3 |
| |
| $4.0 |
| |
| $4.2 |
| |
| $0.7 |
| |
| $0.9 |
| |
| $1.8 |
| |
| $1.9 |
|
| | (a) | Refer to Note 4(a) for discussion of IPL’s sales of accounts receivable program. |
|
|
WPL [Member]
|
|
| Regulatory Assets |
Regulatory Assets - At December 31, regulatory assets were comprised of the following items (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Tax-related |
| $770.7 |
| |
| $634.7 |
| |
| $746.2 |
| |
| $614.6 |
| |
| $24.5 |
| |
| $20.1 |
| Pension and other postretirement benefits costs | 549.2 |
| | 514.1 |
| | 279.3 |
| | 264.9 |
| | 269.9 |
| | 249.2 |
| Asset retirement obligations (AROs) | 62.4 |
| | 65.9 |
| | 38.6 |
| | 48.7 |
| | 23.8 |
| | 17.2 |
| Derivatives | 40.2 |
| | 77.7 |
| | 16.3 |
| | 33.5 |
| | 23.9 |
| | 44.2 |
| Environmental-related costs | 34.9 |
| | 38.9 |
| | 30.3 |
| | 32.2 |
| | 4.6 |
| | 6.7 |
| Emission allowances | 30.0 |
| | 30.0 |
| | 30.0 |
| | 30.0 |
| | — |
| | — |
| Debt redemption costs | 19.8 |
| | 21.8 |
| | 13.6 |
| | 15.1 |
| | 6.2 |
| | 6.7 |
| Proposed clean air compliance projects costs | 16.7 |
| | 14.9 |
| | 7.8 |
| | 6.9 |
| | 8.9 |
| | 8.0 |
| IPL’s electric transmission service costs | 16.6 |
| | 24.9 |
| | 16.6 |
| | 24.9 |
| | — |
| | — |
| Proposed coal-fired base-load projects costs | 14.2 |
| | 21.5 |
| | 10.1 |
| | 15.3 |
| | 4.1 |
| | 6.2 |
| Other | 57.7 |
| | 50.6 |
| | 29.1 |
| | 31.2 |
| | 28.6 |
| | 19.4 |
| |
| $1,612.4 |
| |
| $1,495.0 |
| |
| $1,217.9 |
| |
| $1,117.3 |
| |
| $394.5 |
| |
| $377.7 |
|
|
| Regulatory Liabilities |
Regulatory Liabilities - At December 31, regulatory liabilities were comprised of the following items (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Cost of removal obligations |
| $408.7 |
| |
| $404.9 |
| |
| $268.0 |
| |
| $261.9 |
| |
| $140.7 |
| |
| $143.0 |
| IPL’s tax benefit riders | 355.8 |
| | 349.6 |
| | 355.8 |
| | 349.6 |
| | — |
| | — |
| Energy conservation cost recovery | 55.1 |
| | 29.6 |
| | 10.0 |
| | 4.7 |
| | 45.1 |
| | 24.9 |
| IPL’s electric transmission assets sale | 32.5 |
| | 45.1 |
| | 32.5 |
| | 45.1 |
| | — |
| | — |
| Commodity cost recovery | 17.7 |
| | 23.8 |
| | 5.2 |
| | 23.2 |
| | 12.5 |
| | 0.6 |
| IPL’s DAEC sale | 9.5 |
| | 14.6 |
| | 9.5 |
| | 14.6 |
| | — |
| | — |
| Other | 36.8 |
| | 42.5 |
| | 20.4 |
| | 22.2 |
| | 16.4 |
| | 20.3 |
| |
| $916.1 |
| |
| $910.1 |
| |
| $701.4 |
| |
| $721.3 |
| |
| $214.7 |
| |
| $188.8 |
|
|
| Schedule of Electric Plant in Service |
Electric Plant In Service - Electric plant in service by functional category at December 31 was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Generation |
| $4,798.9 |
| |
| $4,100.6 |
| |
| $2,393.0 |
| |
| $2,392.3 |
| |
| $2,405.9 |
| |
| $1,708.3 |
| Distribution | 3,981.5 |
| | 3,782.1 |
| | 2,205.9 |
| | 2,074.8 |
| | 1,775.6 |
| | 1,707.3 |
| Other | 290.3 |
| | 282.7 |
| | 216.3 |
| | 216.9 |
| | 74.0 |
| | 65.8 |
| |
| $9,070.7 |
| |
| $8,165.4 |
| |
| $4,815.2 |
| |
| $4,684.0 |
| |
| $4,255.5 |
| |
| $3,481.4 |
|
|
| Schedule of Average Rates of Depreciation |
The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows: | | | | | | | | | | | | | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Electric - generation | 3.7% | | 3.5% | | 3.7% | | 3.2% | | 3.3% | | 2.9% | Electric - distribution | 2.5% | | 2.4% | | 2.7% | | 2.9% | | 2.9% | | 2.6% | Gas | 3.4% | | 3.5% | | 3.3% | | 2.6% | | 2.6% | | 2.2% | Other | 4.5% | | 4.8% | | 4.9% | | 5.3% | | 5.2% | | 6.5% |
|
| Schedule of Allowance for Funds Used During Construction |
The amount of AFUDC generated by equity and debt components was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Equity |
| $14.1 |
| |
| $7.6 |
| |
| $11.2 |
| |
| $5.2 |
| |
| $3.5 |
| |
| $3.0 |
| |
| $8.9 |
| |
| $4.1 |
| |
| $8.2 |
| Debt | 7.8 |
| | 4.4 |
| | 6.8 |
| | 3.2 |
| | 2.3 |
| | 2.5 |
| | 4.6 |
| | 2.1 |
| | 4.3 |
| |
| $21.9 |
| |
| $12.0 |
| |
| $18.0 |
| |
| $8.4 |
| |
| $5.8 |
| |
| $5.5 |
| |
| $13.5 |
| |
| $6.2 |
| |
| $12.5 |
|
|
| Schedule of Allowance for Funds Used During Construction Recovery Rate |
The AFUDC recovery rates, computed in accordance with the prescribed regulatory formula, were as follows: | | | | | | | | 2012 | | 2011 | | 2010 | IPL (FERC formula) | 8.2% | | 8.5% | | 4.8% | WPL (PSCW formula - retail jurisdiction) (a) | 8.8% | | 8.8% | | 8.8% | WPL (FERC formula - wholesale jurisdiction) | 7.9% | | 6.2% | | 7.2% |
| | (a) | Consistent with the PSCW’s retail rate case order issued in 2009, WPL earned a current return on 50% of the estimated CWIP related to its Bent Tree - Phase I wind project for 2010 and accrued AFUDC on the remaining 50% in 2010. Consistent with the PSCW’s retail order issued in 2009, WPL accrued AFUDC on 100% of CWIP related to the Edgewater Unit 5 emission controls project and the Columbia Units 1 and 2 emission controls project in 2012, 2011 and 2010. Consistent with the PSCW’s retail rate case order issued in 2012, WPL will earn a return on 50% of the estimated CWIP related to its Columbia Units 1 and 2 emission controls project for 2013 and will accrue AFUDC on the remaining 50% in 2013. |
|
| Schedule of Emission Allowance Amortization Expenses |
Amortization of emission allowances is based upon a weighted average cost for each category of vintage year utilized during the reporting period and is recorded in “Electric production fuel and energy purchases” in the Consolidated Statements of Income as follows (in millions): | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | | 2012 | | 2011 | | 2010 | Amortization expense | $— | | $13.4 | | $16.5 | | $— | | $12.9 | | $13.1 | | $— | | $0.5 | | $3.4 |
|
| Schedule of Allowance for Doubtful Accounts |
Allowance for doubtful accounts at December 31 was as follows (in millions): | | | | | | | | | | | | | | | | | | | | | | | | | | Alliant Energy | | IPL | | WPL | | 2012 | | 2011 | | 2012 | | 2011 | | 2012 | | 2011 | Customer (a) |
| $1.3 |
| |
| $1.6 |
| |
| $— |
| |
| $— |
| |
| $1.3 |
| |
| $1.6 |
| Other | 2.7 |
| | 2.6 |
| | 0.7 |
| | 0.9 |
| | 0.5 |
| | 0.3 |
| |
| $4.0 |
| |
| $4.2 |
| |
| $0.7 |
| |
| $0.9 |
| |
| $1.8 |
| |
| $1.9 |
|
| | (a) | Refer to Note 4(a) for discussion of IPL’s sales of accounts receivable program. |
|
|
WPL [Member] | Riverside Energy Center [Member]
|
|
| Carrying Value of Assets Purchased |
As of the closing date, the carrying values of the assets purchased were as follows (in millions): | | | | | Electric plant in service |
| $512.7 |
| Accumulated depreciation | (121.4 | ) | Current assets | 4.2 |
| Other assets | 8.0 |
| |
| $403.5 |
|
|