Accumulated Other Comprehensive Income (Loss) (Changes in AOCI (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Reclassification Adjustment Out Of AOCI
AOCI, net of deferred income taxes	$ (784)	$ (541)	$ (784)	$ (541)	$ (612)	$ (559)	$ (616)	$ (713)
OCI before reclassification, net of tax	(218)	44	(312)	84
Personnel expense	844	775	1,661	1,505
Total interest income	1,643	1,728	3,302	3,471
Total interest expense	228	266	465	573
Fdic Loss Share Income Net	(85)	(74)	(144)	(131)
Realized gains, net	23	(2)	46	(11)
Income before income taxes	797	729	1,534	1,363
Tax effect	221	191	702	380
Net income	576	538	832	983
Net change in OCI	(172)	75	(225)	172
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of AOCI
Personnel expense	20	17	40	34
Total interest income	22	(11)	70	32
Total interest expense	19	16	40	34
Fdic Loss Share Income Net	35	26	35	30
Realized gains, net	(23)	2	(46)	11
Income before income taxes	73	50	139	141
Tax effect	27	19	52	53
Net income	46	31	87	88
Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment Out Of AOCI
AOCI, net of deferred income taxes	(688)	(581)	(688)	(581)	(700)	(714)	(592)	(603)
OCI before reclassification, net of tax	(1)	1	1	1
Net change in OCI	12	11	26	22
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of AOCI
Personnel expense	20	17	40	34
Income before income taxes	20	17	40	34
Tax effect	7	7	15	13
Net income	13	10	25	21
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Reclassification Adjustment Out Of AOCI
AOCI, net of deferred income taxes	(11)	(174)	(11)	(174)	(166)	(173)	(158)	(159)
OCI before reclassification, net of tax	143	(23)	137	(31)
Net change in OCI	155	(16)	162	(15)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of AOCI
Total interest income		(4)		(8)
Total interest expense	19	16	40	34
Income before income taxes	19	12	40	26
Tax effect	7	5	15	10
Net income	12	7	25	16
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification Adjustment Out Of AOCI
AOCI, net of deferred income taxes	183	455	183	455	537	598	388	263
OCI before reclassification, net of tax	(364)	71	(429)	162
Net change in OCI	(354)	67	(415)	192
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of AOCI
Total interest income	39	(9)	68	37
Realized gains, net	(23)	2	(46)	11
Income before income taxes	16	(7)	22	48
Tax effect	6	(3)	8	18
Net income	10	(4)	14	30
Fdic Share Of Unrealized Gains Losses On Available For Sale Securities Under Loss Share Agreements [Member]
Reclassification Adjustment Out Of AOCI
AOCI, net of deferred income taxes	(252)	(223)	(252)	(223)	(269)	(256)	(237)	(195)
OCI before reclassification, net of tax	7	(3)	(18)	(47)
Net change in OCI	17	14	4	(28)
Fdic Share Of Unrealized Gains Losses On Available For Sale Securities Under Loss Share Agreements [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of AOCI
Total interest income	(19)
Fdic Loss Share Income Net	35	26	35	30
Income before income taxes	16	26	35	30
Tax effect	6	9	13	11
Net income	10	17	22	19
Other [Member]
Reclassification Adjustment Out Of AOCI
AOCI, net of deferred income taxes	(16)	(18)	(16)	(18)	(14)	(14)	(17)	(19)
OCI before reclassification, net of tax	(3)	(2)	(3)	(1)
Net change in OCI	(2)	(1)	(2)	1
Other [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of AOCI
Total interest income	2	2	2	3
Income before income taxes	2	2	2	3
Tax effect	1	1	1	1
Net income	$ 1	$ 1	$ 1	$ 2