Loans and Allowance for Credit Losses (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	$ 5,014	$ 5,531
Provision for credit losses	481	755
Loans charged off	681	899
Less recoveries of loans charged off	(110)	(94)
Net loans charged off	571	805
Net change for credit losses to be reimbursed by the FDIC	(5)	17
Balance at end of year	4,919	5,498
Allowance balance at end of year related to:
Loans individually evaluated for impairment	61		80
TDRs collectively evaluated for impairment	831		839
Other loans collectively evaluated for impairment	3,943		4,016
Loans acquired with deteriorated credit quality	84		79
Total allowance for credit losses	4,919	5,498
Loan balance at end of year:
Loans individually evaluated for impairment	1,174		1,244
TDRs collectively evaluated for impairment	4,912		4,883
Other loans collectively evaluated for impairment	200,029		197,705
Loans acquired with deteriorated credit quality	5,804		6,003
Total loans	211,919		209,835
Commercial loans [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	1,010	1,104
Provision for credit losses	105	174
Loans charged off	113	161
Less recoveries of loans charged off	(27)	(22)
Net loans charged off	86	139
Balance at end of year	1,029	1,139
Allowance balance at end of year related to:
Loans individually evaluated for impairment	12		16
TDRs collectively evaluated for impairment	37		40
Other loans collectively evaluated for impairment	980		954
Loans acquired with deteriorated credit quality
Total allowance for credit losses	1,029	1,139
Loan balance at end of year:
Loans individually evaluated for impairment	184		222
TDRs collectively evaluated for impairment	223		277
Other loans collectively evaluated for impairment	58,371		56,138
Loans acquired with deteriorated credit quality	11		11
Total loans	58,789		56,648
Commercial real estate loans [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	1,154	1,291
Provision for credit losses	(46)	109
Loans charged off	83	140
Less recoveries of loans charged off	(12)	(15)
Net loans charged off	71	125
Balance at end of year	1,037	1,275
Allowance balance at end of year related to:
Loans individually evaluated for impairment	48		61
TDRs collectively evaluated for impairment	32		33
Other loans collectively evaluated for impairment	953		1,057
Loans acquired with deteriorated credit quality	4		3
Total allowance for credit losses	1,037	1,275
Loan balance at end of year:
Loans individually evaluated for impairment	738		812
TDRs collectively evaluated for impairment	381		331
Other loans collectively evaluated for impairment	34,832		34,574
Loans acquired with deteriorated credit quality	151		134
Total loans	36,102		35,851
Residential mortgage loans [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	927	820
Provision for credit losses	112	128
Loans charged off	116	133
Less recoveries of loans charged off	(4)	(4)
Net loans charged off	112	129
Balance at end of year	927	819
Allowance balance at end of year related to:
Loans individually evaluated for impairment	1		1
TDRs collectively evaluated for impairment	498		490
Other loans collectively evaluated for impairment	428		436
Loans acquired with deteriorated credit quality
Total allowance for credit losses	927	819
Loan balance at end of year:
Loans individually evaluated for impairment	6		6
TDRs collectively evaluated for impairment	3,490		3,430
Other loans collectively evaluated for impairment	34,940		33,642
Loans acquired with deteriorated credit quality	5		4
Total loans	38,441		37,082
Credit card portfolio segment [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	992	1,395
Provision for credit losses	178	128
Loans charged off	201	268
Less recoveries of loans charged off	(32)	(21)
Net loans charged off	169	247
Balance at end of year	1,001	1,276
Allowance balance at end of year related to:
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	208		219
Other loans collectively evaluated for impairment	793		773
Loans acquired with deteriorated credit quality
Total allowance for credit losses	1,001	1,276
Loan balance at end of year:
TDRs collectively evaluated for impairment	560		584
Other loans collectively evaluated for impairment	16,012		16,776
Total loans	16,572		17,360
Other retail portfolio segment [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	831	807
Provision for credit losses	124	210
Loans charged off	167	195
Less recoveries of loans charged off	(35)	(32)
Net loans charged off	132	163
Balance at end of year	823	854
Allowance balance at end of year related to:
Loans individually evaluated for impairment
TDRs collectively evaluated for impairment	55		57
Other loans collectively evaluated for impairment	768		774
Loans acquired with deteriorated credit quality
Total allowance for credit losses	823	854
Loan balance at end of year:
TDRs collectively evaluated for impairment	149		148
Other loans collectively evaluated for impairment	47,688		47,959
Total loans	47,837		48,107
Total Loans, Excluding Covered Loans [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	4,914	5,417
Provision for credit losses	473	749
Loans charged off	680	897
Less recoveries of loans charged off	(110)	(94)
Net loans charged off	570	803
Balance at end of year	4,817	5,363
Allowance balance at end of year related to:
Loans individually evaluated for impairment	61		78
TDRs collectively evaluated for impairment	830		839
Other loans collectively evaluated for impairment	3,922		3,994
Loans acquired with deteriorated credit quality	4		3
Total allowance for credit losses	4,817	5,363
Loan balance at end of year:
Loans individually evaluated for impairment	928		1,040
TDRs collectively evaluated for impairment	4,803		4,770
Other loans collectively evaluated for impairment	191,843		189,089
Loans acquired with deteriorated credit quality	167		149
Total loans	197,741		195,048
Covered portfolio segment [Member]
Additional detail of the allowance for credit losses and related loan balances, by portfolio type
Balance at beginning of year	100	114
Provision for credit losses	8	6
Loans charged off	1	2
Net loans charged off	1	2
Net change for credit losses to be reimbursed by the FDIC	(5)	17
Balance at end of year	102	135
Allowance balance at end of year related to:
Loans individually evaluated for impairment			2
TDRs collectively evaluated for impairment	1
Other loans collectively evaluated for impairment	21		22
Loans acquired with deteriorated credit quality	80		76
Total allowance for credit losses	102	135
Loan balance at end of year:
Loans individually evaluated for impairment	246		204
TDRs collectively evaluated for impairment	109		113
Other loans collectively evaluated for impairment	8,186		8,616
Loans acquired with deteriorated credit quality	5,637		5,854
Total loans	$ 14,178		$ 14,787