Changes in AOCI (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Reclassification Adjustments Out Of AOCI [Line Items]
AOCI	$ (406)	$ (784)	$ (406)	$ (784)	$ (500)	$ (593)	$ (612)	$ (559)
OCI before reclassifications, net of tax	78	(218)	157	(312)
Personnel expense	809	844	1,591	1,661
Interest income	1,537	1,643	3,083	3,302
Interest expense	194	228	393	465
FDIC loss share income, net	(88)	(85)	(172)	(144)
Securities (gains) losses, net	0	23	2	46
Income before income taxes	651	797	1,446	1,534
Tax effect	173	221	390	702
Net Income	478	576	1,056	832
Net change in AOCI	94	(172)	187	(225)
Reclassification Out Of AOCI [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
Personnel expense	1	20	1	40
Interest income	(10)	41	(17)	70
Interest expense	19	19	40	40
FDIC loss share income, net	14	16	24	35
Securities (gains) losses, net	0	(23)	(2)	(46)
Income before income taxes	24	73	46	139
Tax effect	8	27	16	52
Net Income	16	46	30	87
Unrecognized Net Pension and Postretirement Costs
Reclassification Adjustments Out Of AOCI [Line Items]
AOCI	(300)	(688)	(300)	(688)	(302)	(303)	(700)	(714)
OCI before reclassifications, net of tax	1	(1)	2	1
Net change in AOCI	2	12	3	26
Unrecognized Net Pension and Postretirement Costs | Reclassification Out Of AOCI [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
Personnel expense	1	20	1	40
Income before income taxes	1	20	1	40
Tax effect	0	7	0	15
Net Income	1	13	1	25
Unrealized Net Gain (Loss) on Cash Flow Hedges
Reclassification Adjustments Out Of AOCI [Line Items]
AOCI	11	(11)	11	(11)	13	2	(166)	(173)
OCI before reclassifications, net of tax	(14)	143	(16)	137
Net change in AOCI	(2)	155	9	162
Unrealized Net Gain (Loss) on Cash Flow Hedges | Reclassification Out Of AOCI [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
Interest expense	19	19	40	40
Income before income taxes	19	19	40	40
Tax effect	7	7	15	15
Net Income	12	12	25	25
Unrealized Net Gains (Losses) on AFS Securities [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
AOCI	123	183	123	183	37	(42)	537	598
OCI before reclassifications, net of tax	89	(364)	174	(429)
Net change in AOCI	86	(354)	165	(415)
Unrealized Net Gains (Losses) on AFS Securities [Member] | Reclassification Out Of AOCI [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
Interest income	(5)	39	(13)	68
Securities (gains) losses, net	0	(23)	(2)	(46)
Income before income taxes	(5)	16	(15)	22
Tax effect	(2)	6	(6)	8
Net Income	(3)	10	(9)	14
FDIC's Share Of Unrealized (Gains) Losses On AFS Securities
Reclassification Adjustments Out Of AOCI [Line Items]
AOCI	(226)	(252)	(226)	(252)	(229)	(235)	(269)	(256)
OCI before reclassifications, net of tax	(6)	7	(6)	(18)
Net change in AOCI	3	17	9	4
FDIC's Share Of Unrealized (Gains) Losses On AFS Securities | Reclassification Out Of AOCI [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
FDIC loss share income, net	14	16	24	35
Income before income taxes	14	16	24	35
Tax effect	5	6	9	13
Net Income	9	10	15	22
Other, net [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
AOCI	(14)	(16)	(14)	(16)	(19)	(15)	(14)	(14)
OCI before reclassifications, net of tax	8	(3)	3	(3)
Net change in AOCI	5	(2)	1	(2)
Other, net [Member] | Reclassification Out Of AOCI [Member]
Reclassification Adjustments Out Of AOCI [Line Items]
Interest income	(5)	2	(4)	2
Income before income taxes	(5)	2	(4)	2
Tax effect	(2)	1	(2)	1
Net Income	$ (3)	$ 1	$ (2)	$ 1