Financial Instruments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Financial instruments including money market funds maturities period		90 days		90 days
Maximum maturities period of long-term marketable securities		3 years		3 years
Minimum maturities period of long-term marketable securities		1 year		1 year
Maximum remaining maturity for short-term marketable securities		12 months		12 months
Minimum maturities of short-term marketable securities		90 days		90 days
Net gain related to forward contracts	$ 2		$ 1
Derivative instruments not designated as hedging instruments, description of terms		Our current forward contracts are not designated as hedges and have current maturities of less than 90 days
Cost method investments		$ 14