Details of Certain Consolidated Statements of Income Lines (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Component of Other Income, Nonoperating [Line Items]
Total other commissions and fees	$ 605	$ 575	$ 1,178	$ 1,158
Foreign currency conversion revenue [Member]
Component of Other Income, Nonoperating [Line Items]
Total other commissions and fees	222	216	432	423
Delinquency fees [Member]
Component of Other Income, Nonoperating [Line Items]
Total other commissions and fees	167	158	331	320
Service fees [Member]
Component of Other Income, Nonoperating [Line Items]
Total other commissions and fees	94	89	176	182
Other commissions and fees [Member]
Component of Other Income, Nonoperating [Line Items]
Total other commissions and fees	$ 122	$ 112	$ 239	$ 233