Investment Securities (Schedule Of Gross Pre-Tax Unrealized Losses On Investment Securities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	$ 10,484	$ 9,124
Available for sale, Gross Unrealized Losses Less than 12 months	87	56
Available for sale, Fair Value 12 months or longer	13,480	15,885
Available for sale, Gross Unrealized Losses 12 months or longer	544	826
Available for sale, Fair Value Total	23,964	25,009
Available for sale, Gross Unrealized Losses Total	631	882
Held to maturity, Fair Value Less than 12 months	6,359	3,968
Held to maturity, Gross Unrealized Losses Less than 12 months	48	10
Held to maturity, Fair Value 12 months or longer	1,306	1,338
Held to maturity, Gross Unrealized Losses 12 months or longer	74	81
Held to maturity, Fair Value Total	7,665	5,306
Held to maturity, Gross Unrealized Losses Total	122	91
Asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,793	2,152
Available for sale, Gross Unrealized Losses Less than 12 months	16	22
Available for sale, Fair Value 12 months or longer	10,477	12,576
Available for sale, Gross Unrealized Losses 12 months or longer	448	712
Available for sale, Fair Value Total	12,270	14,728
Available for sale, Gross Unrealized Losses Total	464	734
Held to maturity, Fair Value Less than 12 months	547
Held to maturity, Gross Unrealized Losses Less than 12 months	1
Held to maturity, Fair Value 12 months or longer	0
Held to maturity, Gross Unrealized Losses 12 months or longer	0
Held to maturity, Fair Value Total	547
Held to maturity, Gross Unrealized Losses Total	1
US Treasury and federal agencies, direct obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	0
Available for sale, Gross Unrealized Losses Less than 12 months	0	0
Available for sale, Fair Value 12 months or longer	120	132
Available for sale, Gross Unrealized Losses 12 months or longer	1	1
Available for sale, Fair Value Total	120	132
Available for sale, Gross Unrealized Losses Total	1	1
Held to maturity, Fair Value Less than 12 months	4,963	3,792
Held to maturity, Gross Unrealized Losses Less than 12 months	37	8
Held to maturity, Fair Value 12 months or longer	0	0
Held to maturity, Gross Unrealized Losses 12 months or longer	0	0
Held to maturity, Fair Value Total	4,963	3,792
Held to maturity, Gross Unrealized Losses Total	37	8
US Treasury and federal agencies, mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	5,276	3,486
Available for sale, Gross Unrealized Losses Less than 12 months	38	18
Available for sale, Fair Value 12 months or longer	769	865
Available for sale, Gross Unrealized Losses 12 months or longer	5	8
Available for sale, Fair Value Total	6,045	4,351
Available for sale, Gross Unrealized Losses Total	43	26
Asset-backed securities, student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	490	625
Available for sale, Gross Unrealized Losses Less than 12 months	7	6
Available for sale, Fair Value 12 months or longer	8,305	10,241
Available for sale, Gross Unrealized Losses 12 months or longer	298	502
Available for sale, Fair Value Total	8,795	10,866
Available for sale, Gross Unrealized Losses Total	305	508
Asset-backed securities, credit cards
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	895	888
Available for sale, Gross Unrealized Losses Less than 12 months	4	3
Available for sale, Fair Value 12 months or longer	0	0
Available for sale, Gross Unrealized Losses 12 months or longer	0	0
Available for sale, Fair Value Total	895	888
Available for sale, Gross Unrealized Losses Total	4	3
Asset-backed securities, sub-prime
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	0
Available for sale, Gross Unrealized Losses Less than 12 months	0	0
Available for sale, Fair Value 12 months or longer	1,317	1,346
Available for sale, Gross Unrealized Losses 12 months or longer	115	162
Available for sale, Fair Value Total	1,317	1,346
Available for sale, Gross Unrealized Losses Total	115	162
Asset-backed securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	408	639
Available for sale, Gross Unrealized Losses Less than 12 months	5	13
Available for sale, Fair Value 12 months or longer	855	989
Available for sale, Gross Unrealized Losses 12 months or longer	35	48
Available for sale, Fair Value Total	1,263	1,628
Available for sale, Gross Unrealized Losses Total	40	61
Total non-U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,666	2,152
Available for sale, Gross Unrealized Losses Less than 12 months	6	5
Available for sale, Fair Value 12 months or longer	389	506
Available for sale, Gross Unrealized Losses 12 months or longer	22	27
Available for sale, Fair Value Total	2,055	2,658
Available for sale, Gross Unrealized Losses Total	28	32
Held to maturity, Fair Value Less than 12 months	422	56
Held to maturity, Gross Unrealized Losses Less than 12 months	3	1
Held to maturity, Fair Value 12 months or longer	1,178	1,185
Held to maturity, Gross Unrealized Losses 12 months or longer	63	70
Held to maturity, Fair Value Total	1,600	1,241
Held to maturity, Gross Unrealized Losses Total	66	71
Non-U.S. debt securities, mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	587	670
Available for sale, Gross Unrealized Losses Less than 12 months	2	3
Available for sale, Fair Value 12 months or longer	346	453
Available for sale, Gross Unrealized Losses 12 months or longer	20	24
Available for sale, Fair Value Total	933	1,123
Available for sale, Gross Unrealized Losses Total	22	27
Held to maturity, Fair Value Less than 12 months	422	56
Held to maturity, Gross Unrealized Losses Less than 12 months	3	1
Held to maturity, Fair Value 12 months or longer	952	956
Held to maturity, Gross Unrealized Losses 12 months or longer	61	67
Held to maturity, Fair Value Total	1,374	1,012
Held to maturity, Gross Unrealized Losses Total	64	68
Non-U.S. debt securities, asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	608	973
Available for sale, Gross Unrealized Losses Less than 12 months	1	1
Available for sale, Fair Value 12 months or longer	43	53
Available for sale, Gross Unrealized Losses 12 months or longer	2	3
Available for sale, Fair Value Total	651	1,026
Available for sale, Gross Unrealized Losses Total	3	4
Held to maturity, Fair Value Less than 12 months	0	0
Held to maturity, Gross Unrealized Losses Less than 12 months	0	0
Held to maturity, Fair Value 12 months or longer	73	73
Held to maturity, Gross Unrealized Losses 12 months or longer	1	1
Held to maturity, Fair Value Total	73	73
Held to maturity, Gross Unrealized Losses Total	1	1
Non-U.S. debt securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	471	509
Available for sale, Gross Unrealized Losses Less than 12 months	3	1
Available for sale, Fair Value 12 months or longer	0	0
Available for sale, Gross Unrealized Losses 12 months or longer	0	0
Available for sale, Fair Value Total	471	509
Available for sale, Gross Unrealized Losses Total	3	1
Held to maturity, Fair Value Less than 12 months	0	0
Held to maturity, Gross Unrealized Losses Less than 12 months	0	0
Held to maturity, Fair Value 12 months or longer	153	156
Held to maturity, Gross Unrealized Losses 12 months or longer	1	2
Held to maturity, Fair Value Total	153	156
Held to maturity, Gross Unrealized Losses Total	1	2
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	859	685
Available for sale, Gross Unrealized Losses Less than 12 months	19	9
Available for sale, Fair Value 12 months or longer	1,144	1,152
Available for sale, Gross Unrealized Losses 12 months or longer	50	58
Available for sale, Fair Value Total	2,003	1,837
Available for sale, Gross Unrealized Losses Total	69	67
Collateralized mortgage obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	616	347
Available for sale, Gross Unrealized Losses Less than 12 months	7	1
Available for sale, Fair Value 12 months or longer	547	621
Available for sale, Gross Unrealized Losses 12 months or longer	12	14
Available for sale, Fair Value Total	1,163	968
Available for sale, Gross Unrealized Losses Total	19	15
Held to maturity, Fair Value Less than 12 months	427	120
Held to maturity, Gross Unrealized Losses Less than 12 months	7	1
Held to maturity, Fair Value 12 months or longer	128	153
Held to maturity, Gross Unrealized Losses 12 months or longer	11	11
Held to maturity, Fair Value Total	555	273
Held to maturity, Gross Unrealized Losses Total	18	12
Other U.S.debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	274	302
Available for sale, Gross Unrealized Losses Less than 12 months	1	1
Available for sale, Fair Value 12 months or longer	34	33
Available for sale, Gross Unrealized Losses 12 months or longer	6	6
Available for sale, Fair Value Total	308	335
Available for sale, Gross Unrealized Losses Total	$ 7	$ 7