Customer Deposits (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
U.S.:
Interest-bearing	$ 39,988	$ 39,649
Non-interest-bearing	187	10
Non-U.S.:
Interest-bearing	123	135
Non-interest-bearing	217	9
Total customer deposits	40,515	39,803
Cardmember Credit Balances [Member]
U.S.:
Non-interest-bearing	166	0
Non-U.S.:
Non-interest-bearing	$ 207	$ 0