Accumulated Other Comprehensive Loss - Narrative (Details) - USD ($) $ in Millions |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
| Estimated interest expense related to settled interest rate hedge contracts during the next twelve months | $ 6 | |
| Estimate of gain related to foreign currency exchange contracts during the next 12 months | 5 | |
| Foreign currency forward exchange contracts | Indian Rupee | ||
| Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
| Notional amount of derivative | 155 | $ 150 |
| Total fair value of cash flow hedge derivatives | $ 5 | $ 8 |