Activity in Allowance for Credit Losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	$ 4,864	$ 5,308	$ 5,014	$ 5,531
Provision for credit losses	488	519	1,439	1,846
Loans charged off	639	762	1,951	2,511
Less recoveries of loans charged off	(101)	(93)	(322)	(290)
Net loans charged off	538	669	1,629	2,221
Net change for credit losses to be reimbursed by the FDIC	(10)	32	(20)	34
Other changes	(33)		(33)
Balance at end of period	4,771	5,190	4,771	5,190
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	1,037	1,109	1,010	1,104
Provision for credit losses	63	15	247	255
Loans charged off	90	126	296	412
Less recoveries of loans charged off	(24)	(27)	(73)	(78)
Net loans charged off	66	99	223	334
Balance at end of period	1,034	1,025	1,034	1,025
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	941	1,258	1,154	1,291
Provision for credit losses	(22)	88	(111)	344
Loans charged off	47	131	206	446
Less recoveries of loans charged off	(22)	(6)	(57)	(32)
Net loans charged off	25	125	149	414
Balance at end of period	894	1,221	894	1,221
Residential Mortgages
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	939	841	927	820
Provision for credit losses	143	168	376	437
Loans charged off	127	124	357	380
Less recoveries of loans charged off	(6)	(2)	(15)	(10)
Net loans charged off	121	122	342	370
Balance at end of period	961	887	961	887
Credit Card
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	996	1,140	992	1,395
Provision for credit losses	119	106	462	314
Loans charged off	186	203	585	712
Less recoveries of loans charged off	(19)	(25)	(79)	(71)
Net loans charged off	167	178	506	641
Other changes	(33)		(33)
Balance at end of period	915	1,068	915	1,068
Other Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	828	843	831	807
Provision for credit losses	185	131	431	477
Loans charged off	187	175	503	551
Less recoveries of loans charged off	(30)	(33)	(97)	(99)
Net loans charged off	157	142	406	452
Balance at end of period	856	832	856	832
Total Loans, Excluding Covered Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	4,741	5,191	4,914	5,417
Provision for credit losses	488	508	1,405	1,827
Loans charged off	637	759	1,947	2,501
Less recoveries of loans charged off	(101)	(93)	(321)	(290)
Net loans charged off	536	666	1,626	2,211
Other changes	(33)		(33)
Balance at end of period	4,660	5,033	4,660	5,033
Covered Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	123	117	100	114
Provision for credit losses		11	34	19
Loans charged off	2	3	4	10
Less recoveries of loans charged off			(1)
Net loans charged off	2	3	3	10
Net change for credit losses to be reimbursed by the FDIC	(10)	32	(20)	34
Balance at end of period	$ 111	$ 157	$ 111	$ 157