Loans and Allowance for Credit Losses - Activity in Allowance for Credit Losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	$ 4,497	$ 4,708	$ 4,537	$ 4,733
Provision for credit losses	324	362	630	765
Loans charged off	432	506	854	1,055
Less recoveries of loans charged off	(83)	(114)	(164)	(230)
Net loans charged off	349	392	690	825
Other changes	(23)	(66)	(28)	(61)
Balance at end of period	4,449	4,612	4,449	4,612
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	1,091	1,012	1,075	1,051
Provision for credit losses	75	49	127	45
Loans charged off	76	63	139	119
Less recoveries of loans charged off	(21)	(25)	(48)	(46)
Net loans charged off	55	38	91	73
Other changes
Balance at end of period	1,111	1,023	1,111	1,023
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	742	798	776	857
Provision for credit losses	(21)	(38)	(58)	(78)
Loans charged off	9	16	17	59
Less recoveries of loans charged off	(13)	(33)	(24)	(57)
Net loans charged off	(4)	(17)	(7)	2
Other changes
Balance at end of period	725	777	725	777
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	862	926	875	935
Provision for credit losses	43	69	87	152
Loans charged off	62	81	123	181
Less recoveries of loans charged off	(5)	(7)	(9)	(15)
Net loans charged off	57	74	114	166
Other changes
Balance at end of period	848	921	848	921
Credit Card [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	884	895	884	863
Provision for credit losses	163	152	333	344
Loans charged off	188	191	372	384
Less recoveries of loans charged off	(18)	(18)	(32)	(51)
Net loans charged off	170	173	340	333
Other changes	(3)		(3)
Balance at end of period	874	874	874	874
Other Retail [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	785	854	781	848
Provision for credit losses	63	89	143	221
Loans charged off	95	134	195	290
Less recoveries of loans charged off	(26)	(29)	(50)	(59)
Net loans charged off	69	105	145	231
Other changes
Balance at end of period	779	838	779	838
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	4,364	4,485	4,391	4,554
Provision for credit losses	323	321	632	684
Loans charged off	430	485	846	1,033
Less recoveries of loans charged off	(83)	(112)	(163)	(228)
Net loans charged off	347	373	683	805
Other changes	(3)		(3)
Balance at end of period	4,337	4,433	4,337	4,433
Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	133	223	146	179
Provision for credit losses	1	41	(2)	81
Loans charged off	2	21	8	22
Less recoveries of loans charged off		(2)	(1)	(2)
Net loans charged off	2	19	7	20
Other changes	(20)	(66)	(25)	(61)
Balance at end of period	$ 112	$ 179	$ 112	$ 179