Changes in AOCI (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
AOCI Changes and Reclassifications
AOCI, net of deferred income taxes	$ (860)	$ (409)	$ (860)	$ (409)	$ (784)	$ (559)	$ (541)	$ (713)
OCI before reclassification, net of tax	(115)	81	(427)	165
Personnel expense	805	797	2,466	2,302
Iinterest income	1,639	1,720	4,941	5,191
Interest expense	222	237	687	810
FDIC loss share income, net	(74)	(90)	(218)	(221)
Realized gains, net	0	(1)	46	(12)
Income before income taxes	759	673	2,293	2,036
Tax effect	450	177	1,152	557
Net income	309	496	1,141	1,479
Net change in OCI	(76)	132	(301)	304
Amounts reclassified from AOCI [Member]
AOCI Changes and Reclassifications
Personnel expense	20	18	60	52
Iinterest income	5	22	75	54
Interest expense	18	19	58	53
FDIC loss share income, net	21	25	56	55
Realized gains, net	0	(1)	(46)	10
Income before income taxes	64	83	203	224
Tax effect	25	32	77	85
Net income	39	51	126	139
Unrecognized Net Pension and Postretirement Costs
AOCI Changes and Reclassifications
AOCI, net of deferred income taxes	(687)	(582)	(687)	(582)	(688)	(714)	(581)	(603)
OCI before reclassification, net of tax	(11)	(12)	(10)	(11)
Net change in OCI	1	(1)	27	21
Unrecognized Net Pension and Postretirement Costs | Amounts reclassified from AOCI [Member]
AOCI Changes and Reclassifications
Personnel expense	20	18	60	52
Income before income taxes	20	18	60	52
Tax effect	8	7	23	20
Net income	12	11	37	32
Unrealized Net Gain (Loss) on Cash Flow Hedges
AOCI Changes and Reclassifications
AOCI, net of deferred income taxes	(8)	(184)	(8)	(184)	(11)	(173)	(174)	(159)
OCI before reclassification, net of tax	(8)	(21)	129	(52)
Net change in OCI	3	(10)	165	(25)
Unrealized Net Gain (Loss) on Cash Flow Hedges | Amounts reclassified from AOCI [Member]
AOCI Changes and Reclassifications
Iinterest income		(2)		(10)
Interest expense	18	19	58	53
Income before income taxes	18	17	58	43
Tax effect	7	6	22	16
Net income	11	11	36	27
Accumulated Net Unrealized Investment Gain (Loss) [Member]
AOCI Changes and Reclassifications
AOCI, net of deferred income taxes	88	607	88	607	183	598	455	263
OCI before reclassification, net of tax	(98)	140	(527)	302
Net change in OCI	(95)	152	(510)	344
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Amounts reclassified from AOCI [Member]
AOCI Changes and Reclassifications
Iinterest income	5	21	73	58
Realized gains, net	0	(1)	(46)	10
Income before income taxes	5	20	27	68
Tax effect	2	8	10	26
Net income	3	12	17	42
FDIC's Share Of Unrealized (Gains) Losses On AFS Securities
AOCI Changes and Reclassifications
AOCI, net of deferred income taxes	(239)	(236)	(239)	(236)	(252)	(256)	(223)	(195)
OCI before reclassification, net of tax	0	(28)	(18)	(75)
Net change in OCI	13	(13)	17	(41)
FDIC's Share Of Unrealized (Gains) Losses On AFS Securities | Amounts reclassified from AOCI [Member]
AOCI Changes and Reclassifications
FDIC loss share income, net	21	25	56	55
Income before income taxes	21	25	56	55
Tax effect	8	10	21	21
Net income	13	15	35	34
Other, Net [Member]
AOCI Changes and Reclassifications
AOCI, net of deferred income taxes	(14)	(14)	(14)	(14)	(16)	(14)	(18)	(19)
OCI before reclassification, net of tax	2	2	(1)	1
Net change in OCI	2	4	0	5
Other, Net [Member] | Amounts reclassified from AOCI [Member]
AOCI Changes and Reclassifications
Iinterest income	0	3	2	6
Income before income taxes	0	3	2	6
Tax effect	0	1	1	2
Net income	$ 0	$ 2	$ 1	$ 4