Pension Plans and Other Postretirement Benefits Amounts Recognized in Other Comprehensive Income - Level 4 (Details) - USD ($) $ in Millions |
2 Months Ended | 10 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Dec. 31, 2014 |
Oct. 24, 2014 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2013 |
|
| Defined Benefit Plan Disclosure [Line Items] | |||||
| Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | $ 1 | $ 4 | $ 0 | ||
| Defined Benefit Plan, Amortization of Gains (Losses) | 0 | 0 | 0 | ||
| Other Comprehensive Income (Loss), Net of Tax | (28) | (202) | 16 | $ (64) | |
| United States Postretirement Benefit Plan of US Entity, Defined Benefit [Member] | |||||
| Defined Benefit Plan Disclosure [Line Items] | |||||
| Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | $ 0 | $ 0 | $ (3) | $ 0 | |