Financial Statement Schedule (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts, Current [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 87	$ 86	$ 103
Charged/Credited to Net Income	177	135	65
Charged to Other Accounts	0	0	0
Charges Utilized/Write-offs	(175)	(134)	(82)
Balance at End of Period	89	87	86
Allowance for Trasaction, Loan and Interest Losses [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	193	137	148
Charged/Credited to Net Income	573	482	360
Charged to Other Accounts	0	0	0
Charges Utilized/Write-offs	(538)	(426)	(371)
Balance at End of Period	228	193	137
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	83	43	69
Charged/Credited to Net Income	16	33	1
Charged to Other Accounts	78	0	0
Charges Utilized/Write-offs	(8)	7	(27)
Balance at End of Period	$ 169	$ 83	$ 43