Loans and Allowance for Credit Losses - Additional Detail of Allowance for Credit Losses and Related Loan Balances by Portfolio Type (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Allowance Balance at End of Period
Loans individually evaluated for impairment	$ 31	$ 32
TDRs collectively evaluated for impairment	500	520
Other loans collectively evaluated for impairment	3,802	3,815
Loans acquired with deteriorated credit quality	164	170
Total allowance for credit losses	4,497	4,537	4,708	4,733
Loan balance at end of period
Loans individually evaluated for impairment	578	496
TDRs collectively evaluated for impairment	6,249	6,243
Other loans collectively evaluated for impairment	227,770	224,557
Loans acquired with deteriorated credit quality	3,778	3,939
Total loans	230,276	226,773
Total loans	238,375	235,235
Commercial [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment	19	15
TDRs collectively evaluated for impairment	15	19
Other loans collectively evaluated for impairment	1,057	1,041
Loans acquired with deteriorated credit quality
Total allowance for credit losses	1,091	1,075	1,012	1,051
Loan balance at end of period
Loans individually evaluated for impairment	282	197
TDRs collectively evaluated for impairment	136	155
Other loans collectively evaluated for impairment	73,281	69,680
Loans acquired with deteriorated credit quality	2	1
Total loans	73,701	70,033
Commercial Real Estate [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment	12	17
TDRs collectively evaluated for impairment	20	26
Other loans collectively evaluated for impairment	674	700
Loans acquired with deteriorated credit quality	36	33
Total allowance for credit losses	742	776	798	857
Loan balance at end of period
Loans individually evaluated for impairment	214	237
TDRs collectively evaluated for impairment	327	358
Other loans collectively evaluated for impairment	39,452	39,129
Loans acquired with deteriorated credit quality	138	161
Total loans	40,131	39,885
Residential Mortgages [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	333	329
Other loans collectively evaluated for impairment	529	546
Loans acquired with deteriorated credit quality
Total allowance for credit losses	862	875	926	935
Loan balance at end of period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	5,142	5,064
Other loans collectively evaluated for impairment	46,565	46,090
Loans acquired with deteriorated credit quality	1	2
Total loans	51,708	51,156
Credit Card [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	77	87
Other loans collectively evaluated for impairment	807	797
Loans acquired with deteriorated credit quality
Total allowance for credit losses	884	884	895	863
Loan balance at end of period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	289	310
Other loans collectively evaluated for impairment	16,840	17,711
Loans acquired with deteriorated credit quality
Total loans	17,129	18,021
Other Retail [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	51	55
Other loans collectively evaluated for impairment	734	726
Loans acquired with deteriorated credit quality
Total allowance for credit losses	785	781	854	848
Loan balance at end of period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	263	269
Other loans collectively evaluated for impairment	47,344	47,409
Loans acquired with deteriorated credit quality
Total loans	47,607	47,678
Total Loans, Excluding Covered Loans [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment	31	32
TDRs collectively evaluated for impairment	496	516
Other loans collectively evaluated for impairment	3,801	3,810
Loans acquired with deteriorated credit quality	36	33
Total allowance for credit losses	4,364	4,391	4,485	4,554
Loan balance at end of period
Loans individually evaluated for impairment	496	434
TDRs collectively evaluated for impairment	6,157	6,156
Other loans collectively evaluated for impairment	223,482	220,019
Loans acquired with deteriorated credit quality	141	164
Total loans	230,276	226,773
Covered Loans [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	4	4
Other loans collectively evaluated for impairment	1	5
Loans acquired with deteriorated credit quality	128	137
Total allowance for credit losses	133	146	223	179
Loan balance at end of period
Loans individually evaluated for impairment	82	62
TDRs collectively evaluated for impairment	92	87
Other loans collectively evaluated for impairment	4,288	4,538
Loans acquired with deteriorated credit quality	3,637	3,775
Total loans	$ 8,099	$ 8,462