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Statements of Consolidated Changes in Equity - USD ($) $ in Millions | Total | Depositary Shares [Member] | Common Stock [Member] | Capital in Excess of Par Value of Shares [Member] | Retained Earnings [Member] | Common Shares in Treasury [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Noncontrolling Interest [Member] | Depositary Shares [Member] | Depositary Shares [Member] Capital in Excess of Par Value of Shares [Member]
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Balance, beginning of period (in shares) at Dec. 31, 2012 |  |  | 142,500,000 |  |  |  |  |  |  |
Balance, beginning of period at Dec. 31, 2012 | $ 5,760.9 |  | $ 18.5 | $ 1,774.7 | $ 3,217.7 | $ (322.6) | $ (55.6) | $ 1,128.2 |  |
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] |  |  |  |  |  |  |  |  |  |
NET INCOME (LOSS) | 361.8 |  |  |  | 413.5 |  |  | (51.7) |  |
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | (356.2) |  |  |  |  |  | (57.3) |  |  |
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest |  |  |  |  |  |  |  | 30.5 |  |
Other Comprehensive Income (Loss), Net of Tax | (26.8) |  |  |  |  |  |  |  |  |
Pension and OPEB liability, net of tax | 208.3 |  |  |  |  |  |  |  |  |
Unrealized net loss on marketable securities, net of tax | 3.1 |  |  |  |  |  |  |  |  |
Total comprehensive income (loss) | 335.0 |  |  |  |  |  |  | (21.2) |  |
Stock Issued During Period, Value, New Issues | 285.3 | $ (731.3) | $ (1.3) | 284.0 |  |  |  |  | $ (709.4) | $ 21.9
Equity offering (in shares) |  | 29,300,000 | 10,400,000 |  |  |  |  |  |  |
Undistributed losses to noncontrolling interest to subsidiary | 17.0 |  |  |  |  |  |  | 17.0 |  |
Capital contribution by noncontrolling interest to subsidiary | 5.2 |  |  | 0.2 | (0.6) |  |  | 5.6 |  |
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests |  |  |  | (295.4) | (82.7) |  |  |  |  |
Stock Issued During Period, Value, Acquisitions | (102.1) |  |  |  |  |  |  | (314.8) |  |
Stock and other incentive plans (in shares) |  |  | 300,000 |  |  |  |  |  |  |
Stock and other incentive plans | 14.2 |  |  | (2.9) |  | 17.1 |  |  |  |
Common stock dividends ($0.60 per share) | (91.9) |  |  |  | 91.9 |  |  |  |  |
Preferred stock dividends ($1.66 per depositary share) | (48.7) |  |  |  | (48.7) |  |  |  |  |
Balance, end of period (in shares) at Dec. 31, 2013 |  |  | 153,200,000 |  |  |  |  |  |  |
Balance, end of period at Dec. 31, 2013 | 6,884.3 | $ 731.3 | $ 19.8 | 2,329.5 | 3,407.3 | (305.5) | (112.9) | 814.8 |  |
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] |  |  |  |  |  |  |  |  |  |
Preferred Stock, Shares Outstanding |  | 29,300,000 |  |  |  |  |  |  |  |
NET INCOME (LOSS) | (8,311.6) |  |  |  | (7,224.2) |  |  | (1,087.4) |  |
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | 7,357.1 |  |  |  |  |  | (132.9) |  |  |
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest |  |  |  |  |  |  |  | (4.8) |  |
Other Comprehensive Income (Loss), Net of Tax | (137.7) |  |  |  |  |  |  |  |  |
Pension and OPEB liability, net of tax | (91.0) |  |  |  |  |  |  |  |  |
Unrealized net loss on marketable securities, net of tax | (7.2) |  |  |  |  |  |  |  |  |
Total comprehensive income (loss) | (8,449.3) |  |  |  |  |  |  | (1,092.2) |  |
Undistributed losses to noncontrolling interest to subsidiary | (25.5) |  |  |  |  |  |  | (25.5) |  |
Capital contribution by noncontrolling interest to subsidiary | (0.1) |  |  |  |  |  |  | (0.1) |  |
Stock and other incentive plans | 0.1 |  |  | (19.7) |  | 19.8 |  |  |  |
Common stock dividends ($0.60 per share) | (92.5) |  |  |  | (92.5) |  |  |  |  |
Preferred stock dividends ($1.66 per depositary share) | (51.2) |  |  |  |  |  |  |  |  |
Preferred Stock Dividends | $ (51.3) |  |  |  | (51.3) |  |  |  |  |
Balance, end of period (in shares) at Dec. 31, 2014 | 153,246,754 |  | 153,200,000 |  |  |  |  |  |  |
Balance, end of period at Dec. 31, 2014 | $ (1,734.3) | $ 731.3 | $ 19.8 | 2,309.8 | (3,960.7) | (285.7) | (245.8) | (303.0) |  |
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] |  |  |  |  |  |  |  |  |  |
Preferred Stock, Shares Outstanding |  | 29,300,000 |  |  |  |  |  |  |  |
NET INCOME (LOSS) | (748.4) |  |  |  | (749.3) |  |  | 0.9 |  |
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | 521.5 |  |  |  |  |  | 227.8 |  |  |
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest |  |  |  |  |  |  |  | (4.6) |  |
Other Comprehensive Income (Loss), Net of Tax | 223.2 |  |  |  |  |  |  |  |  |
Pension and OPEB liability, net of tax | 45.2 |  |  |  |  |  |  |  |  |
Unrealized net loss on marketable securities, net of tax | 1.7 |  |  |  |  |  |  |  |  |
Total comprehensive income (loss) | (525.2) |  |  |  |  |  |  | (3.7) |  |
Undistributed losses to noncontrolling interest to subsidiary | (0.2) |  |  |  |  |  |  | (0.2) |  |
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders | (51.7) |  |  |  |  |  |  | (51.7) |  |
Deconsolidation, Gain (Loss), Amount | 528.2 |  |  |  |  |  |  | 528.2 |  |
Capital contribution by noncontrolling interest to subsidiary | 0.2 |  |  |  |  |  |  | 0.2 |  |
Stock and other incentive plans (in shares) |  |  | 300,000 |  |  |  |  |  |  |
Stock and other incentive plans | 9.8 |  |  | (10.9) |  | 20.7 |  |  |  |
Preferred stock dividends ($1.66 per depositary share) | (38.4) |  |  |  |  |  |  |  |  |
Preferred Stock Dividends | $ (38.4) |  |  |  | (38.4) |  |  |  |  |
Balance, end of period (in shares) at Dec. 31, 2015 | 153,591,930 |  | 153,500,000 |  |  |  |  |  |  |
Balance, end of period at Dec. 31, 2015 | $ (1,811.6) | $ 731.3 | $ 19.8 | $ 2,298.9 | $ (4,748.4) | $ (265.0) | $ (18.0) | $ 169.8 |  |
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] |  |  |  |  |  |  |  |  |  |
Preferred Stock, Shares Outstanding |  | 29,300,000 |  |  |  |  |  |  |  |

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