Summary of Significant Accounting Policies - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of the period	$ (74)	$ (63)	$ (60)
Other comprehensive loss before reclassifications		(21)	(11)
Amounts reclassified from accumulated other comprehensive loss		10	8
Total other comprehensive loss		(11)	(3)	$ 0
Balance at end of the period		(74)	(63)	(60)
Interest expense		169	163	163
Designated as hedging instrument | Foreign currency forward exchange contracts | Indian Rupee
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Notional amount		85	73
Total fair value		(1)	(1)
Forecast | Designated as hedging instrument | Interest rate contract
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Interest expense	12
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of the period	(31)	(41)	(49)
Other comprehensive loss before reclassifications		0	0
Amounts reclassified from accumulated other comprehensive loss		10	8
Total other comprehensive loss		10	8
Balance at end of the period		(31)	(41)	(49)
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of the period	(41)	(20)	(9)
Other comprehensive loss before reclassifications		(21)	(11)
Amounts reclassified from accumulated other comprehensive loss		0	0
Total other comprehensive loss		(21)	(11)
Balance at end of the period		(41)	(20)	(9)
Other
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of the period	$ (2)	(2)	(2)
Other comprehensive loss before reclassifications		0	0
Amounts reclassified from accumulated other comprehensive loss		0	0
Total other comprehensive loss		0	0
Balance at end of the period		$ (2)	$ (2)	$ (2)