Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Statement of Comprehensive Income [Abstract] | ||
| Actuarial changes, tax | $ 3 | $ 3 |
| Prior service costs, tax | (2) | (4) |
| Other, tax | $ (1) | $ 0 |