Fair Value Measurements - Foreign Currency Forward Contracts (Details) - Foreign currency forward contracts - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Not Designated as Hedges
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivatives	$ 0	$ 489,000,000
Fair value of foreign currency forward contracts		11,000,000
Unrealized gain reclassified out of AOCI and into earnings due to discontinuance of foreign currency cash flow hedge		8,000,000
Notional amount of dedesignated cash flow hedge		250,000,000
Designated as Hedges | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivatives	346,000,000	381,000,000
Fair value of foreign currency forward contracts	22,000,000	(4,000,000)
Net realized but unrecognized gains with remaining maturities of 12 months or less	22,000,000
Deferred Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	7,000,000
Ineffective portion relating to these hedges	$ 0	$ 0
Maximum length of time over which our foreign currency forward contracts mature	12 months