Fair Value Measurement of Assets and Liabilities - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Funds receivable and customer accounts	$ 11,352	$ 10,545
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	$ 166	$ 215
Bank Time Deposits, US Treasury And Government, And Foreign Government And Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Funds receivable and customer accounts	$ 5,800