Employee Benefit Plans (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Employee Benefit Plans [Abstract] | |||
| Defined Contribution Plan, Cost | $ 20 | $ 25 | $ 27 |
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Amount of cost for defined contribution plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|