Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Statement Of Income And Comprehensive Income [Abstract] | ||||
| Actuarial loss, tax | $ 1 | $ 1 | $ 3 | $ 3 |
| Unrealized loss on cash flow hedge, tax | $ (3) | $ 0 | $ (10) | $ 0 |