Financial Statement Schedule (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowances for Doubtful Accounts and Authorized Credits
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	$ 86	$ 88	$ 74
Charged/Credited to Net Income	66	77	64
Charged to Other Account	0	0	0
Charges Utilized/Write-offs	(68)	(79)	(50)
Balance at End of Period	84	86	88
Allowance for Transaction Losses
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	27	23	20
Charged/Credited to Net Income	205	185	172
Charged to Other Account	0	0	0
Charges Utilized/Write-offs	(198)	(181)	(169)
Balance at End of Period	34	27	23
Tax Valuation Allowance
Movement in Valuation Allowances and Reserves
Balance at Beginning of Period	25	164	149
Charged/Credited to Net Income	19	(138)	33
Charged to Other Account	(3)	(1)	(2)
Charges Utilized/Write-offs	0	0	(16)
Balance at End of Period	$ 41	$ 25	$ 164