Details of Certain Consolidated Statements of Income Lines (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Component of Other Income, Nonoperating [Line Items]
Other commissions and fees	$ 581	$ 604	$ 1,739	$ 1,717
Foreign currency conversion revenue [Member]
Component of Other Income, Nonoperating [Line Items]
Other commissions and fees	220	225	643	651
Delinquency fees [Member]
Component of Other Income, Nonoperating [Line Items]
Other commissions and fees	156	155	476	439
Service fees [Member]
Component of Other Income, Nonoperating [Line Items]
Other commissions and fees	81	89	263	266
Other Commissions And Fees [Member]
Component of Other Income, Nonoperating [Line Items]
Other commissions and fees	$ 124	$ 135	$ 357	$ 361