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	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Allowance Balance at End of Period
Loans individually evaluated for impairment	$ 22		$ 40
TDRs collectively evaluated for impairment	665		754
Other loans collectively evaluated for impairment	3,748		3,771
Loans acquired with deteriorated credit quality	177		168
Total allowance for credit losses	4,612	4,708	4,733	4,864	4,919	5,014
Loan balance at end of period
Loans individually evaluated for impairment	605		729
TDRs collectively evaluated for impairment	5,637		5,675
Other loans collectively evaluated for impairment	217,341		211,514
Loans acquired with deteriorated credit quality	4,392		5,411
Total Loans	217,990		212,021
Total loans	227,975		223,329
Commercial [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment	8		10
TDRs collectively evaluated for impairment	24		28
Other loans collectively evaluated for impairment	991		1,013
Loans acquired with deteriorated credit quality
Total allowance for credit losses	1,023	1,012	1,051	1,037	1,029	1,010
Loan balance at end of period
Loans individually evaluated for impairment	155		171
TDRs collectively evaluated for impairment	186		185
Other loans collectively evaluated for impairment	67,841		65,863
Loans acquired with deteriorated credit quality	3		4
Total Loans	68,185		66,223
Commercial Real Estate [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment	14		30
TDRs collectively evaluated for impairment	23		29
Other loans collectively evaluated for impairment	729		791
Loans acquired with deteriorated credit quality	11		7
Total allowance for credit losses	777	798	857	941	1,037	1,154
Loan balance at end of period
Loans individually evaluated for impairment	413		510
TDRs collectively evaluated for impairment	376		391
Other loans collectively evaluated for impairment	37,424		35,952
Loans acquired with deteriorated credit quality	85		100
Total Loans	38,298		36,953
Residential Mortgages [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	398		446
Other loans collectively evaluated for impairment	523		489
Loans acquired with deteriorated credit quality
Total allowance for credit losses	921	926	935	939	927	927
Loan balance at end of period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	4,317		4,199
Other loans collectively evaluated for impairment	43,431		39,813
Loans acquired with deteriorated credit quality	5		6
Total Loans	47,753		44,018
Credit Card [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	114		153
Other loans collectively evaluated for impairment	760		710
Loans acquired with deteriorated credit quality
Total allowance for credit losses	874	895	863	996	1,001	992
Loan balance at end of period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	358		442
Other loans collectively evaluated for impairment	16,291		16,673
Loans acquired with deteriorated credit quality
Total Loans	16,649		17,115
Other Retail [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	101		97
Other loans collectively evaluated for impairment	737		751
Loans acquired with deteriorated credit quality
Total allowance for credit losses	838	854	848	828	823	831
Loan balance at end of period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	291		313
Other loans collectively evaluated for impairment	46,814		47,399
Loans acquired with deteriorated credit quality
Total Loans	47,105		47,712
Total Loans, Excluding Covered Loans [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment	22		40
TDRs collectively evaluated for impairment	660		753
Other loans collectively evaluated for impairment	3,740		3,754
Loans acquired with deteriorated credit quality	11		7
Total allowance for credit losses	4,433	4,485	4,554	4,741	4,817	4,914
Loan balance at end of period
Loans individually evaluated for impairment	568		681
TDRs collectively evaluated for impairment	5,528		5,530
Other loans collectively evaluated for impairment	211,801		205,700
Loans acquired with deteriorated credit quality	93		110
Total Loans	217,990		212,021
Covered Loans [Member]
Allowance Balance at End of Period
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	5		1
Other loans collectively evaluated for impairment	8		17
Loans acquired with deteriorated credit quality	166		161
Total allowance for credit losses	179	223	179	123	102	100
Loan balance at end of period
Loans individually evaluated for impairment	37		48
TDRs collectively evaluated for impairment	109		145
Other loans collectively evaluated for impairment	5,540		5,814
Loans acquired with deteriorated credit quality	4,299		5,301
Total loans	$ 9,985		$ 11,308