Employee Benefit Plans - Schedule of Pre-Tax Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions |
Dec. 31, 2017 |
Dec. 31, 2016 |
---|---|---|
Defined Pension Benefits | ||
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract] | ||
Prior service cost | $ 0 | $ 0 |
Net actuarial gain (loss) | (49) | (66) |
Accumulated other comprehensive (loss) income | (49) | (66) |
Other Postretirement Benefits | ||
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract] | ||
Prior service cost | (2) | (2) |
Net actuarial gain (loss) | 10 | 12 |
Accumulated other comprehensive (loss) income | $ 8 | $ 10 |