Fair Value Measurement of Assets and Liabilities - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Designated as Hedging Instrument | Minimum | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract duration	1 month
Designated as Hedging Instrument | Maximum | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract duration	1 year
Cash Flow Hedging | Designated as Hedging Instrument | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract duration	18 months
Long-Term Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost and equity method investments included in long-term investments	$ 123	$ 184