Reserves for Losses (Details 1) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Cardmember Receivables And Related Reserves Evaluated Separately and Collectively For Impairment [Abstract]
Cardmember receivables evaluated separately for impairment	$ 69	$ 117
Reserves on cardmember receivables evaluated separately for impairment	68	91
Cardmember receivables evaluated collectively for impairment	44,028	42,649
Reserves on cardmember receivables evaluated collectively for impairment	$ 318	$ 337