Loans and Allowance for Credit Losses - Activity in Allowance for Credit Losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	$ 4,612	$ 4,864	$ 4,733	$ 5,014
Provision for credit losses	298	488	1,063	1,439
Loans charged off	450	639	1,505	1,951
Less recoveries of loans charged off	(122)	(101)	(352)	(322)
Net loans charged off	328	538	1,153	1,629
Other changes	(4)	(43)	(65)	(53)
Balance at end of period	4,578	4,771	4,578	4,771
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	1,023	1,037	1,051	1,010
Provision for credit losses	19	63	64	247
Loans charged off	65	90	184	296
Less recoveries of loans charged off	(54)	(24)	(100)	(73)
Net loans charged off	11	66	84	223
Other changes
Balance at end of period	1,031	1,034	1,031	1,034
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	777	941	857	1,154
Provision for credit losses	(22)	(22)	(100)	(111)
Loans charged off	17	47	76	206
Less recoveries of loans charged off	(23)	(22)	(80)	(57)
Net loans charged off	(6)	25	(4)	149
Other changes
Balance at end of period	761	894	761	894
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	921	939	935	927
Provision for credit losses	70	143	222	376
Loans charged off	62	127	243	357
Less recoveries of loans charged off	(5)	(6)	(20)	(15)
Net loans charged off	57	121	223	342
Other changes
Balance at end of period	934	961	934	961
Credit Card [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	874	996	863	992
Provision for credit losses	151	119	495	462
Loans charged off	175	186	559	585
Less recoveries of loans charged off	(15)	(19)	(66)	(79)
Net loans charged off	160	167	493	506
Other changes		(33)		(33)
Balance at end of period	865	915	865	915
Other Retail [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	838	828	848	831
Provision for credit losses	84	185	305	431
Loans charged off	122	187	412	503
Less recoveries of loans charged off	(24)	(30)	(83)	(97)
Net loans charged off	98	157	329	406
Other changes
Balance at end of period	824	856	824	856
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	4,433	4,741	4,554	4,914
Provision for credit losses	302	488	986	1,405
Loans charged off	441	637	1,474	1,947
Less recoveries of loans charged off	(121)	(101)	(349)	(321)
Net loans charged off	320	536	1,125	1,626
Other changes		(33)		(33)
Balance at end of period	4,415	4,660	4,415	4,660
Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	179	123	179	100
Provision for credit losses	(4)		77	34
Loans charged off	9	2	31	4
Less recoveries of loans charged off	(1)		(3)	(1)
Net loans charged off	8	2	28	3
Other changes	(4)	(10)	(65)	(20)
Balance at end of period	$ 163	$ 111	$ 163	$ 111