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Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |  |  | 3 Months Ended | 4 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Aug. 23, 2017 | Apr. 01, 2017 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Apr. 01, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Jul. 03, 2017
Earnings per Share (EPS) (Textuals) [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Antidilutive shares excluded from EPS calculation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.6 |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Treasury stock, shares, acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5.8 |  |  |
Successor |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Earnings per Share (EPS) (Textuals) [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Antidilutive shares excluded from EPS calculation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.1 |  |  |
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.2 |  |  |
EPS numerator: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, net of income taxes |  |  |  | $ 378.0 |  | $ 233.7 |  | $ 101.4 |  |  |  |  |  |  |  |  |  |  |  |  |  | 713.1 |  |  |
Preferred Stock Dividends, Income Statement Impact |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 179.5 |  |  |
Less: Net income attributable to noncontrolling interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15.2 |  |  |
Loss from continuing operations attributable to common stockholders, before allocation of earnings to participating securities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 518.4 |  |  |
Less: Earnings allocated to participating securities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 129.0 |  |  |
Loss from continuing operations attributable to common stockholders, after allocation of earnings to participating securities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 389.4 |  |  |
Income (Loss) from discontinued operations, net of tax, including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (19.8) |  |  |
Loss from discontinued operations allocated to participating securities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (4.9) |  |  |
Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Basic |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (14.9) |  |  |
Net loss attributable to common stockholders, after earnings allocated to participating securities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 374.5 |  |  |
EPS denominator: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average shares outstanding, basic |  |  |  | 104.8 |  | 101.6 |  | 96.8 |  |  |  |  |  |  |  |  |  |  |  |  |  | 101.1 |  |  |
Weighted average number of shares outstanding, basic and diluted |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 102.5 |  |  |
Weighted average number diluted shares outstanding adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.4 |  |  |
Weighted average shares outstanding, diluted |  |  |  | 106.5 |  | 103.1 |  | 96.8 |  |  |  |  |  |  |  |  |  |  |  |  |  | 33.5 |  |  |
Basic EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, per basic share |  |  |  | $ 2.50 | [1] | $ 1.51 | [1] | $ (0.18) | [1] |  |  |  |  |  |  |  |  |  |  |  |  | $ 3.85 |  |  |
Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (0.15) |  |  |
Net income (loss) attributable to common stockholders, per basic share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.70 |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, per diluted share |  |  |  | $ 2.47 | [1] | $ 1.49 | [1] | $ (0.18) | [1] |  |  |  |  |  |  |  |  |  |  |  |  | 3.81 |  |  |
Income (loss) from discontinued operations, net of tax, per diluted share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (0.14) |  |  |
Net income (loss) attributable to common stockholders, per diluted share |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3.67 |  |  |
Conversion of Stock, Shares Converted |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (17.2) |  |  |
Conversion of Stock, Shares Issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6.2 |  |  |
Treasury stock, shares, acquired | 1.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.3 |  |  |  |
Predecessor |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Earnings per Share (EPS) (Textuals) [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Antidilutive shares excluded from EPS calculation |  |  |  |  |  |  |  |  |  | 0.2 |  |  |  |  |  |  |  |  |  |  |  |  | 0.4 | 0.6 |
EPS numerator: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, net of income taxes |  | $ (319.8) |  |  |  |  |  |  |  | $ (195.5) | $ 124.3 |  | $ (175.2) |  | $ (97.7) |  | $ (223.2) |  | $ (167.7) |  |  |  | $ (663.8) | $ (1,783.2) |
Preferred Stock Dividends, Income Statement Impact |  |  |  |  |  |  |  |  |  | 0.0 |  |  |  |  |  |  |  |  |  |  |  |  | 0.0 | 0.0 |
Less: Net income attributable to noncontrolling interests |  |  |  |  |  |  |  |  |  | 4.8 |  |  |  |  |  |  |  |  |  |  |  |  | 7.9 | 7.1 |
Loss from continuing operations attributable to common stockholders, before allocation of earnings to participating securities |  |  |  |  |  |  |  |  |  | (200.3) |  |  |  |  |  |  |  |  |  |  |  |  | (671.7) | (1,790.3) |
Less: Earnings allocated to participating securities |  |  |  |  |  |  |  |  |  | 0.0 |  |  |  |  |  |  |  |  |  |  |  |  | 0.0 | 0.0 |
Loss from continuing operations attributable to common stockholders, after allocation of earnings to participating securities |  |  |  |  |  |  |  |  |  | (200.3) |  |  |  |  |  |  |  |  |  |  |  |  | (671.7) | (1,790.3) |
Income (Loss) from discontinued operations, net of tax, including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |  | (16.2) |  |  | $ 13.1 |  | $ 38.1 |  |  |  |  |  |  |  | (57.6) | (175.0) |
Loss from discontinued operations allocated to participating securities |  |  |  |  |  |  |  |  |  | 0.0 |  |  |  |  |  |  |  |  |  |  |  |  | 0.0 | 0.0 |
Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Basic |  |  |  |  |  |  |  |  |  | (16.2) |  |  |  |  |  |  |  |  |  |  |  |  | (57.6) | (175.0) |
Net loss attributable to common stockholders, after earnings allocated to participating securities |  |  |  |  |  |  |  |  |  | $ (216.5) |  |  |  |  |  |  |  |  |  |  |  |  | $ (729.3) | $ (1,965.3) |
EPS denominator: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average shares outstanding, basic |  | 18.3 |  |  |  |  |  |  |  | 18.3 | 18.3 |  | 18.3 |  | 18.3 |  | 18.3 |  | 18.3 |  |  |  | 18.3 | 18.1 |
Weighted average number of shares outstanding, basic and diluted |  |  |  |  |  |  |  |  |  | 18.3 |  |  |  |  |  |  |  |  |  |  |  |  | 18.3 | 18.1 |
Weighted average number diluted shares outstanding adjustment |  |  |  |  |  |  |  |  |  | 0.0 |  |  |  |  |  |  |  |  |  |  |  |  | 0.0 | 0.0 |
Weighted average shares outstanding, diluted |  | 18.3 |  |  |  |  |  |  |  |  | 18.4 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basic EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, per basic share |  | $ (17.44) | [1] |  |  |  |  |  |  | $ (10.93) | $ 6.46 | [1] | $ (9.82) | [2] | $ (5.44) | [2] | $ (12.30) | [2] | $ (9.17) | [2] |  |  | $ (36.72) | $ (98.65) |
Income (Loss) from Continuing Operations, Per Basic and Diluted Share |  |  |  |  |  |  |  |  |  | (10.93) |  |  |  |  |  |  |  |  |  |  |  |  | (36.72) | (98.65) |
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic and Diluted Share |  |  |  |  |  |  |  |  |  | (0.88) |  |  |  |  |  |  |  |  |  |  |  |  | (3.15) | (9.64) |
Net income (loss) attributable to common stockholders, per basic share |  |  |  |  |  |  |  |  |  | (11.81) |  |  |  |  |  |  |  |  |  |  |  |  | (39.87) | (108.29) |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Income (loss) from continuing operations, per diluted share |  | $ (17.44) | [1] |  |  |  |  |  |  | (10.93) | $ 6.44 | [1] |  |  |  |  |  |  |  |  |  |  | (36.72) | (98.65) |
Income (loss) from discontinued operations, net of tax, per diluted share |  |  |  |  |  |  |  |  |  | (0.88) |  |  |  |  |  |  |  |  |  |  |  |  | (3.15) | (9.64) |
Net income (loss) attributable to common stockholders, per diluted share |  |  |  |  |  |  |  |  |  | $ (11.81) |  |  |  |  |  |  |  |  |  |  |  |  | $ (39.87) | $ (108.29) |
Common Stock | Successor |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion of Stock, Shares Issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40.0 |  |  |
Warrant | Successor |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants unexercised, percent |  |  |  | 0.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.00% | 0.00% |  |  |
Preferred Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion of Stock, Shares Converted |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 17.2 |  |  |
Effect of Plan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued (in shares) |  |  |  | 130.7 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 130.7 | 130.7 |  |  |
Effect of Plan | Successor |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued (in shares) |  | 70.9 |  |  |  |  |  |  |  | 70.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Effect of Plan | Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diluted EPS attributable to common stockholders: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants unexercised, percent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.10%
[1] | EPS for the quarters may not sum to the amounts for the year as each period is computed on a discrete basis.
[2] | EPS for the quarters may not sum to the amounts for the year as each period is computed on a discrete basis

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