Changes in AOCI (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
AOCI	$ (593)	$ (559)	$ (713)	$ (747)
OCI before reclassifications, net of tax	(208)	(43)	(10)
Personnel expense	3,293	3,125	2,727
Interest income	6,507	6,917	6,885
Interest expense	891	1,060	1,378
FDIC loss share income, net	(293)	(318)	(289)
Securities (gains) losses, net	51	(12)	62
Income before income taxes	3,124	2,792	1,628
Tax effect	1,395	764	296
Net income	1,729	2,028	1,332
Net change in AOCI	(34)	154	34
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
Personnel expense	91	76	34
Interest income	99	73	(24)
Interest expense	77	72	72
FDIC loss share income, net	63	83	50
Securities (gains) losses, net	(51)	12	(62)
Income before income taxes	279	316	70
Tax effect	105	119	26
Net income	174	197	44
Unrecognized Net Pension and Postretirement Costs
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
AOCI	(303)	(714)	(603)	(368)
OCI before reclassifications, net of tax	354	(158)	(256)
Net change in AOCI	411	(111)	(235)
Unrecognized Net Pension and Postretirement Costs | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
Personnel expense	91	76	34
Income before income taxes	91	76	34
Tax effect	34	29	13
Net income	57	47	21
Unrealized Net Gain (Loss) on Cash Flow Hedges
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
AOCI	2	(173)	(159)	(47)
OCI before reclassifications, net of tax	127	(52)	(141)
Net change in AOCI	175	(14)	(112)
Unrealized Net Gain (Loss) on Cash Flow Hedges | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
Interest income		(11)	(26)
Interest expense	77	72	72
Income before income taxes	77	61	46
Tax effect	29	23	17
Net income	48	38	29
Unrealized Net Gains (Losses) on AFS Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
AOCI	(42)	598	263	(157)
Transfers between categories of AOCI			21
OCI before reclassifications, net of tax	(669)	280	440
Net change in AOCI	(640)	335	420
Unrealized Net Gains (Losses) on AFS Securities [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
Interest income	97	76	(4)
Securities (gains) losses, net	(51)	12	(62)
Income before income taxes	46	88	(66)
Tax effect	17	33	(25)
Net income	29	55	(41)
FDIC's Share Of Unrealized (Gains) Losses On AFS Securities
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
AOCI	(235)	(256)	(195)	(176)
OCI before reclassifications, net of tax	(18)	(113)	(50)
Net change in AOCI	21	(61)	(19)
FDIC's Share Of Unrealized (Gains) Losses On AFS Securities | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
FDIC loss share income, net	63	83	50
Income before income taxes	63	83	50
Tax effect	24	31	19
Net income	39	52	31
Other, net [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
AOCI	(15)	(14)	(19)	1
Transfers between categories of AOCI			(21)
OCI before reclassifications, net of tax	(2)	0	(3)
Net change in AOCI	(1)	5	(20)
Other, net [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income
Interest income	2	8	6
Income before income taxes	2	8	6
Tax effect	1	3	2
Net income	$ 1	$ 5	$ 4