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Pension and Postretirement Health and Life Benefits (Tables) | 12 Months Ended
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Dec. 31, 2012
Pension and Postretirement Health and Life Benefits |
Schedule of Changes in Projected Benefit Obligations [Table Text Block] |
|  | Defined Benefit Pension Plans |  |  | Postretirement Health and Life Benefit Plans |
|  | Years Ended December 31, |  |  | Years Ended December 31, |
Changes in Benefit Obligations: |  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |
Obligations at beginning of year |  | $ | 989.5 |  |  | $ | 876.8 |  |  | $ | 252.9 |  |  | $ | 230.6 |
Actuarial (gains) losses, net |  |  | 104.6 |  |  |  | 93.4 |  |  |  | (7.2 | ) |  |  | 14.7 |
Service costs |  |  | 14.6 |  |  |  | 16.2 |  |  |  | 3.7 |  |  |  | 4.3 |
Interest costs |  |  | 48.3 |  |  |  | 50.3 |  |  |  | 11.1 |  |  |  | 12.2 |
Gross benefits paid |  |  | (58.0 | ) |  |  | (50.4 | ) |  |  | (12.3 | ) |  |  | (11.5 | )
Less federal subsidy on benefits paid |  |  | - |  |  |  | - |  |  |  | 0.6 |  |  |  | 0.7 |
Curtailment losses |  |  | - |  |  |  | 3.2 |  |  |  | - |  |  |  | 1.9 |
Obligations at end of year |  |  | 1,099.0 |  |  |  | 989.5 |  |  |  | 248.8 |  |  |  | 252.9 |
Changes in Plan Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of plan assets at beginning of year |  |  | 727.8 |  |  |  | 728.5 |  |  |  | 45.1 |  |  |  | 51.9 |
Actual return on plan assets |  |  | 91.3 |  |  |  | 34.1 |  |  |  | 5.8 |  |  |  | (1.8 | )
USEC contributions |  |  | 13.7 |  |  |  | 15.6 |  |  |  | 3.0 |  |  |  | 6.5 |
Benefits paid |  |  | (58.0 | ) |  |  | (50.4 | ) |  |  | (12.3 | ) |  |  | (11.5 | )
Fair value of plan assets at end of year |  |  | 774.8 |  |  |  | 727.8 |  |  |  | 41.6 |  |  |  | 45.1 |
(Unfunded) status at end of year |  |  | (324.2 | ) |  |  | (261.7 | ) |  |  | (207.2 | ) |  |  | (207.8 | )
Amounts recognized in assets and liabilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current liabilities |  | $ | (2.5 | ) |  | $ | (3.4 | ) |  | $ | - |  |  | $ | - |
Noncurrent liabilities |  |  | (321.7 | ) |  |  | (258.3 | ) |  |  | (207.2 | ) |  |  | (207.8 | )
|  | $ | (324.2 | ) |  | $ | (261.7 | ) |  | $ | (207.2 | ) |  | $ | (207.8 | )
Amounts recognized in accumulated other comprehensive income, pre-tax: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net actuarial loss |  | $ | 326.0 |  |  | $ | 280.5 |  |  | $ | 45.3 |  |  | $ | 59.9 |
Prior service cost (credit) |  |  | 1.7 |  |  |  | 3.2 |  |  |  | - |  |  |  | - |
|  | $ | 327.7 |  |  | $ | 283.7 |  |  | $ | 45.3 |  |  | $ | 59.9 |
Schedule of Net Benefit Costs |
|  | Defined Benefit Pension Plans |  |  | Postretirement Health and Life Benefit Plans |
(in millions) |  | Years Ended December 31, |  |  | Years Ended December 31, |
|  | 2012 |  |  | 2011 |  |  | 2010 |  |  | 2012 |  |  | 2011 |  |  | 2010 |
Net Periodic Benefit Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service costs |  | $ | 14.6 |  |  | $ | 16.2 |  |  | $ | 19.3 |  |  | $ | 3.7 |  |  | $ | 4.3 |  |  | $ | 5.0 |
Interest costs |  |  | 48.3 |  |  |  | 50.3 |  |  |  | 48.9 |  |  |  | 11.1 |  |  |  | 12.2 |  |  |  | 11.9 |
Expected return on plan assets (gains) |  |  | (52.0 | ) |  |  | (54.0 | ) |  |  | (48.7 | ) |  |  | (2.9 | ) |  |  | (3.7 | ) |  |  | (3.6 | )
Amortization of prior service costs (credits) |  |  | 1.5 |  |  |  | 1.7 |  |  |  | 1.8 |  |  |  | - |  |  |  | - |  |  |  | (8.5 | )
Amortization of actuarial (gains) losses, net |  |  | 19.7 |  |  |  | 9.4 |  |  |  | 16.0 |  |  |  | 4.5 |  |  |  | 2.6 |  |  |  | 2.7 |
Curtailment losses |  |  | - |  |  |  | 3.2 |  |  |  | 0.4 |  |  |  | - |  |  |  | 1.9 |  |  |  | - |
Net periodic benefit costs |  | $ | 32.1 |  |  | $ | 26.8 |  |  | $ | 37.7 |  |  | $ | 16.4 |  |  | $ | 17.3 |  |  | $ | 7.5 |
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] |
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net valuation (gain) loss |  | $ | 65.2 |  |  | $ | 115.4 |  |  | $ | (36.7 | ) |  | $ | (10.1 | ) |  | $ | 20.8 |  |  | $ | 3.2 |
Amortization of actuarial (gains) losses, net |  |  | (19.7 | ) |  |  | (11.6 | ) |  |  | (16.0 | ) |  |  | (4.5 | ) |  |  | (4.6 | ) |  |  | (2.7 | )
Amortization of prior service costs (credits) |  |  | (1.5 | ) |  |  | (1.6 | ) |  |  | (2.2 | ) |  |  | - |  |  |  | - |  |  |  | 8.5 |
Total (gain) loss recognized in other comprehensive income (loss), pre-tax |  | $ | 44.0 |  |  | $ | 102.2 |  |  | $ | (54.9 | ) |  | $ | (14.6 | ) |  | $ | 16.2 |  |  | $ | 9.0 |
Total (gain) loss recognized in net periodic benefit costs (income) and other comprehensive income (loss), pre-tax |  | $ | 76.1 |  |  | $ | 129.0 |  |  | $ | (17.2 | ) |  | $ | 1.8 |  |  | $ | 33.5 |  |  | $ | 16.5 |
Schedule of Assumptions Used [Table Text Block] |
Assumptions used to determine net periodic benefit costs: |  |  |
Discount rate |  |  | 4.95 | % |  |  | 5.77 | % |  |  | 5.84 | % |  |  | 4.46 | % |  |  | 5.32 | % |  |  | 5.44 | %
Expected return on plan assets |  |  | 7.25 |  |  |  | 7.50 |  |  |  | 7.50 |  |  |  | 7.25 |  |  |  | 7.50 |  |  |  | 7.50 |
Compensation increases |  |  | 4.25 |  |  |  | 4.25 |  |  |  | 4.25 |  |  |  | 4.25 |  |  |  | 4.25 |  |  |  | 4.25 |
Schedule of Health Care Cost Trend Rates [Table Text Block] |
|  | December 31, |
|  | 2012 |  |  | 2011 |
Healthcare cost trend rate for the following year |  |  | 7.50 | % |  |  | 8.00 | %
Long-term rate that the healthcare cost trend rate gradually declines to |  |  | 5 | % |  |  | 5 | %
Year that the healthcare cost trend rate is expected to reach the long-term rate |  |  | 2018 |  |  |  | 2018 |
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] |
|  | One Percentage Point |
|  | Increase |  |  | Decrease |
Postretirement health benefit obligation |  | $ | 7.3 |  |  | $ | (6.9 | )
Net periodic benefit costs |  | $ | 0.8 |  |  | $ | (0.7 | )
Schedule of Allocation of Plan Assets [Table Text Block] |
| Percentage of Plan Assets | Target Allocation Range
| December 31, |
| 2012 | 2011 | 2013
Defined Benefit Pension Plans: |  |  |  |
Equity securities | 52% | 50% | 40 - | - 60%
Debt securities | 48 | 50 | 40 - | - 60
| 100% | 100% |  |
Postretirement Health and Life Benefit Plans: |  |  |  |
Equity securities | 65% | 69% | 55 - | - 75%
Debt securities | 35 | 31 | 25 - | 45
| 100% | 100% |  |
Schedule of Fair Value of Pension Plan Assets |
|  | Defined Benefit Pension Plans |
|  | Level 1 |  |  | Level 2 |  |  | Level 3 |  |  | Total |
|  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |
U.S. government securities |  | $ | - |  |  | $ | - |  |  | $ | 89.8 |  |  | $ | 70.1 |  |  | $ | - |  |  | $ | - |  |  | $ | 89.8 |  |  | $ | 70.1 |
Collective trust – money market funds |  |  | - |  |  |  | - |  |  |  | 16.5 |  |  |  | 21.4 |  |  |  | - |  |  |  | - |  |  |  | 16.5 |  |  |  | 21.4 |
Collective trust – bond funds |  |  | - |  |  |  | - |  |  |  | 47.7 |  |  |  | 41.5 |  |  |  | - |  |  |  | - |  |  |  | 47.7 |  |  |  | 41.5 |
Collective trust – equity funds |  |  | - |  |  |  | - |  |  |  | 397.4 |  |  |  | 362.9 |  |  |  | - |  |  |  | - |  |  |  | 397.4 |  |  |  | 362.9 |
Preferred equity |  |  | - |  |  |  | 0.3 |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | 0.3 |
Corporate debt |  |  | - |  |  |  | - |  |  |  | 211.1 |  |  |  | 218.1 |  |  |  | 0.6 |  |  |  | 0.9 |  |  |  | 211.7 |  |  |  | 219.0 |
Municipal bonds |  |  | - |  |  |  | - |  |  |  | 7.8 |  |  |  | 7.2 |  |  |  | - |  |  |  | - |  |  |  | 7.8 |  |  |  | 7.2 |
Mortgage and asset backed securities |  |  | - |  |  |  | - |  |  |  | 0.2 |  |  |  | 0.8 |  |  |  | - |  |  |  | - |  |  |  | 0.2 |  |  |  | 0.8 |
Fair value of investments by hierarchy level |  | $ | - |  |  | $ | 0.3 |  |  | $ | 770.5 |  |  | $ | 722.0 |  |  | $ | 0.6 |  |  | $ | 0.9 |  |  | $ | 771.1 |  |  | $ | 723.2 |
Accrued interest receivable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.8 |  |  |  | 4.2 |
Unsettled transactions payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (0.1 | ) |  |  | 0.4 |
Plan assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ | 774.8 |  |  | $ | 727.8 |
Schedule of Fair Value of Postretirement Benefit Plan Assets |
|  | Postretirement Health and Life Benefit Plans |
|  | Level 1 |  |  | Level 2 |  |  | Level 3 |  |  | Total |
|  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |  |  | 2012 |  |  | 2011 |
Money market funds |  | $ | 0.8 |  |  | $ | 1.2 |  |  | $ | - |  |  | $ | - |  |  | $ | - |  |  | $ | - |  |  | $ | 0.8 |  |  | $ | 1.2 |
Bond mutual funds |  |  | 13.7 |  |  |  | 14.4 |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | 13.7 |  |  |  | 14.4 |
Equity mutual funds |  |  | 27.1 |  |  |  | 29.5 |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | - |  |  |  | 27.1 |  |  |  | 29.5 |
Fair value of investments by hierarchy level |  | $ | 41.6 |  |  | $ | 45.1 |  |  | $ | - |  |  | $ | - |  |  | $ | - |  |  | $ | - |  |  | $ | 41.6 |  |  | $ | 45.1 |
Reconciliation of Fair Value of Assets Using Unobservable Inputs |
|  | Corporate Debt |
Beginning balance |  | $ | 0.9 |
Transfer out to Level 2 |  |  | (0.9 | )
Transfer in from Level 2 |  |  | 0.1 |
New purchases |  |  | 0.5 |
Ending balance |  | $ | 0.6 |
Schedule of Estimated Future Benefit Payments |
|  | Defined Benefit Pension Plans |  |  | Postretirement Health and Life Benefit Plans |  |  | Expected Subsidies From Medicare |
2013 |  | $ | 60.9 |  |  | $ | 15.3 |  |  | $ | 0.7 |
2014 |  |  | 59.9 |  |  |  | 16.3 |  |  |  | 0.9 |
2015 |  |  | 71.3 |  |  |  | 18.4 |  |  |  | 1.1 |
2016 |  |  | 60.4 |  |  |  | 21.0 |  |  |  | 1.3 |
2017 |  |  | 60.8 |  |  |  | 22.7 |  |  |  | 1.5 |
2018 to 2022 |  |  | 311.3 |  |  |  | 112.8 |  |  |  | 10.3 |

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