Net Income (Loss) Per Common Share - Reconciliation (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions |
1 Months Ended |
2 Months Ended |
3 Months Ended |
10 Months Ended |
12 Months Ended |
Dec. 31, 2017 |
Dec. 15, 2017 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2016 |
| Numerator |
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| Net income (loss) |
$ 237
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$ 268
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$ (88)
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$ (130)
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$ 287
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| Dividends and accretion to preferred stockholders |
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0
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| Undistributed earnings |
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$ 287
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| Percentage allocated to common stockholders |
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100.00%
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| Numerator for basic and diluted earnings (loss) per common share |
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$ 287
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| Weighted average shares outstanding |
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| Denominator for basic earnings per weighted average common shares (in shares) |
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109.9
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| Effect of dilutive securities |
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| Warrants (in shares) |
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0.0
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| Denominator for diluted earnings (loss) per weighted average common shares (in shares) |
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111.1
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| Net income (loss) per common share |
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| Basic (in usd per share) |
$ 2.16
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$ 2.44
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$ (0.80)
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$ (1.18)
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$ 2.61
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| Diluted (in usd per share) |
$ 2.15
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$ 2.41
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$ (0.80)
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$ (1.18)
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$ 2.58
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| Weighted average number of shares - basic (in shares) |
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109.9
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| Basic weighted average common stock and common stock equivalents (preferred shares) (in shares) |
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109.9
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| Restricted stock units |
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| Effect of dilutive securities |
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| Share-based payment arrangements (in shares) |
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1.2
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| Stock options |
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| Effect of dilutive securities |
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| Share-based payment arrangements (in shares) |
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0.0
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| Convertible Notes |
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| Effect of dilutive securities |
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| Share-based payment arrangements (in shares) |
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0.0
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| Warrants |
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| Effect of dilutive securities |
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| Warrants (in shares) |
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0.0
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| Predecessor |
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| Numerator |
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| Net income (loss) |
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$ 2,977
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$ 27
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$ (98)
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$ (8)
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$ (103)
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$ (182)
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$ (730)
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| Dividends and accretion to preferred stockholders |
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(6)
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(31)
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(41)
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| Undistributed earnings |
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$ 2,971
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$ (213)
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$ (771)
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| Percentage allocated to common stockholders |
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86.90%
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100.00%
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100.00%
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| Numerator for basic and diluted earnings (loss) per common share |
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$ 2,582
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$ (213)
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$ (771)
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| Weighted average shares outstanding |
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| Denominator for basic earnings per weighted average common shares (in shares) |
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497.3
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497.1
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500.7
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| Effect of dilutive securities |
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| Warrants (in shares) |
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0.0
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0.0
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0.0
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| Denominator for diluted earnings (loss) per weighted average common shares (in shares) |
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497.3
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497.1
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500.7
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| Net income (loss) per common share |
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| Basic (in usd per share) |
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$ 5.19
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$ 0.04
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$ (0.22)
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$ (0.03)
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$ (0.22)
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$ (0.43)
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$ (1.54)
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| Diluted (in usd per share) |
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$ 5.19
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$ 0.04
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$ (0.22)
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$ (0.03)
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$ (0.22)
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$ (0.43)
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$ (1.54)
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| Weighted average number of shares - basic (in shares) |
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497.3
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497.1
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500.7
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| Basic weighted average common stock and common stock equivalents (preferred shares) (in shares) |
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572.4
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497.1
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500.7
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| Predecessor | Restricted stock units |
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| Effect of dilutive securities |
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| Share-based payment arrangements (in shares) |
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0.0
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0.0
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0.0
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| Predecessor | Stock options |
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| Effect of dilutive securities |
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| Share-based payment arrangements (in shares) |
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0.0
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0.0
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0.0
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| Predecessor | Convertible Notes |
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| Effect of dilutive securities |
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| Share-based payment arrangements (in shares) |
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0.0
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0.0
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0.0
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| Predecessor | Warrants |
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| Effect of dilutive securities |
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| Warrants (in shares) |
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0.0
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0.0
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0.0
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