Variable Interest Entities and Securitizations - Carrying Amount of Assets and Liabilities of Variable Interest Entities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	$ 40,261	$ 44,674
Carrying Amount of Liabilities, Consolidated	11,979	13,633
Carrying Amount of Assets, Unconsolidated	3,194	2,809
Carrying Amount of Liabilities, Unconsolidated	442	521
Maximum Exposure to Loss, Unconsolidated	3,217	2,834
Securitization-Related VIEs [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	39,871	44,298
Carrying Amount of Liabilities, Consolidated	11,881	13,545
Carrying Amount of Assets, Unconsolidated	201	212
Carrying Amount of Liabilities, Unconsolidated	17	17
Maximum Exposure to Loss, Unconsolidated	224	237
Securitization-Related VIEs [Member] | Credit Card Loan Securitizations [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	39,837	44,238
Carrying Amount of Liabilities, Consolidated	11,850	13,488
Carrying Amount of Assets, Unconsolidated	0	0
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum Exposure to Loss, Unconsolidated	0	0
Securitization-Related VIEs [Member] | Home Loan Securitizations [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	34	41
Carrying Amount of Liabilities, Consolidated	31	38
Carrying Amount of Assets, Unconsolidated	201	212
Carrying Amount of Liabilities, Unconsolidated	17	17
Maximum Exposure to Loss, Unconsolidated	224	237
Securitization-Related VIEs [Member] | Other Asset Securitizations [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	0	19
Carrying Amount of Liabilities, Consolidated	0	19
Carrying Amount of Assets, Unconsolidated	0	0
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum Exposure to Loss, Unconsolidated	0	0
Other VIEs [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	390	376
Carrying Amount of Liabilities, Consolidated	98	88
Carrying Amount of Assets, Unconsolidated	2,993	2,597
Carrying Amount of Liabilities, Unconsolidated	425	504
Maximum Exposure to Loss, Unconsolidated	2,993	2,597
Other VIEs [Member] | Affordable Housing Entities [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	0	0
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	2,887	2,390
Carrying Amount of Liabilities, Unconsolidated	420	414
Maximum Exposure to Loss, Unconsolidated	2,887	2,390
Other VIEs [Member] | Entities that Provide Capital to Low-Income and Rural Communities [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	389	375
Carrying Amount of Liabilities, Consolidated	98	88
Carrying Amount of Assets, Unconsolidated	6	6
Carrying Amount of Liabilities, Unconsolidated	5	4
Maximum Exposure to Loss, Unconsolidated	6	6
Other VIEs [Member] | Other [Member]
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	1	1
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	100	201
Carrying Amount of Liabilities, Unconsolidated	0	86
Maximum Exposure to Loss, Unconsolidated	$ 100	$ 201