Fair Value Measurement of Assets and Liabilities - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Assets:
Funds receivable and customer accounts	$ 12,232	$ 12,261
Derivatives	15
Liabilities:
Derivatives	18
Fair value, measurements, recurring basis
Assets:
Cash and cash equivalents	2,583	1,393
Funds receivable and customer accounts	6,586	6,978
Derivatives	104	97
Total financial assets	13,073	12,808
Liabilities:
Derivatives	107	25
Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	1,918	987
Funds receivable and customer accounts	0	0
Derivatives	0	0
Total financial assets	1,943	1,013
Liabilities:
Derivatives	0	0
Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	665	406
Funds receivable and customer accounts	6,586	6,978
Derivatives	104	97
Total financial assets	11,130	11,795
Liabilities:
Derivatives	107	25
Corporate debt securities
Assets:
Funds receivable and customer accounts	190	180
Government and agency securities
Assets:
Funds receivable and customer accounts	5,063	4,305
Time deposits
Assets:
Funds receivable and customer accounts	526	830
Short-term investments
Assets:
Funds receivable and customer accounts	5,800	5,300
Short-term investments | Fair value, measurements, recurring basis
Assets:
Investments	2,184	2,018
Short-term investments | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	17	18
Short-term investments | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	2,167	2,000
Short-term investments | Restricted cash | Fair value, measurements, recurring basis
Assets:
Investments	17	18
Short-term investments | Restricted cash | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	17	18
Short-term investments | Restricted cash | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	0	0
Short-term investments | Corporate debt securities | Fair value, measurements, recurring basis
Assets:
Investments	2,140	1,998
Short-term investments | Corporate debt securities | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	0	0
Short-term investments | Corporate debt securities | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	2,140	1,998
Short-term investments | Government and agency securities | Fair value, measurements, recurring basis
Assets:
Investments	10
Short-term investments | Government and agency securities | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	0
Short-term investments | Government and agency securities | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	10
Short-term investments | Time deposits | Fair value, measurements, recurring basis
Assets:
Investments	17	2
Short-term investments | Time deposits | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	0	0
Short-term investments | Time deposits | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	17	2
Long-term investments | Fair value, measurements, recurring basis
Assets:
Investments	1,616	2,322
Long-term investments | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	8	8
Long-term investments | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	1,608	2,314
Long-term investments | Restricted cash | Fair value, measurements, recurring basis
Assets:
Investments	8	8
Long-term investments | Restricted cash | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	8	8
Long-term investments | Restricted cash | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	0	0
Long-term investments | Corporate debt securities | Fair value, measurements, recurring basis
Assets:
Investments	1,608	2,314
Long-term investments | Corporate debt securities | Fair value, measurements, recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Investments	0	0
Long-term investments | Corporate debt securities | Fair value, measurements, recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Investments	$ 1,608	$ 2,314