Investment Securities (Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	$ 29,495	$ 9,124
Available for sale, Gross Unrealized Losses Less than 12 months	576	56
Available for sale, Fair Value 12 months or longer	13,303	15,885
Available for sale, Gross Unrealized Losses 12 months or longer	617	826
Available for sale, Fair Value Total	42,798	25,009
Available for sale, Gross Unrealized Losses Total	1,193	882
Held to maturity, Fair Value Less than 12 months	7,870	3,968
Held to maturity, Gross Unrealized Losses Less than 12 months	354	10
Held to maturity, Fair Value 12 months or longer	1,022	1,338
Held to maturity, Gross Unrealized Losses 12 months or longer	84	81
Held to maturity, Fair Value Total	8,892	5,306
Held to maturity, Gross Unrealized Losses Total	438	91
Asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	8,342	2,152
Available for sale, Gross Unrealized Losses Less than 12 months	91	22
Available for sale, Fair Value 12 months or longer	9,945	12,576
Available for sale, Gross Unrealized Losses 12 months or longer	503	712
Available for sale, Fair Value Total	18,287	14,728
Available for sale, Gross Unrealized Losses Total	594	734
Held to maturity, Fair Value Less than 12 months	1,332
Held to maturity, Gross Unrealized Losses Less than 12 months	16
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	1,332
Held to maturity, Gross Unrealized Losses Total	16
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	4,698	3,792
Held to maturity, Gross Unrealized Losses Less than 12 months	302	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	4,698	3,792
Held to maturity, Gross Unrealized Losses Total	302	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	10,463	3,486
Available for sale, Gross Unrealized Losses Less than 12 months	236	18
Available for sale, Fair Value 12 months or longer	1,391	865
Available for sale, Gross Unrealized Losses 12 months or longer	21	8
Available for sale, Fair Value Total	11,854	4,351
Available for sale, Gross Unrealized Losses Total	257	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	2,913	625
Available for sale, Gross Unrealized Losses Less than 12 months	36	6
Available for sale, Fair Value 12 months or longer	7,887	10,241
Available for sale, Gross Unrealized Losses 12 months or longer	360	502
Available for sale, Fair Value Total	10,800	10,866
Available for sale, Gross Unrealized Losses Total	396	508
Held to maturity, Fair Value Less than 12 months	1,074
Held to maturity, Gross Unrealized Losses Less than 12 months	14
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	1,074
Held to maturity, Gross Unrealized Losses Total	14
Asset-backed securities, credit cards
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	4,883	888
Available for sale, Gross Unrealized Losses Less than 12 months	49	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	4,883	888
Available for sale, Gross Unrealized Losses Total	49	3
Held to maturity, Fair Value Less than 12 months	67
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	67
Held to maturity, Gross Unrealized Losses Total	1
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	1,248	1,346
Available for sale, Gross Unrealized Losses 12 months or longer	113	162
Available for sale, Fair Value Total	1,248	1,346
Available for sale, Gross Unrealized Losses Total	113	162
Asset-backed securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	546	639
Available for sale, Gross Unrealized Losses Less than 12 months	6	13
Available for sale, Fair Value 12 months or longer	810	989
Available for sale, Gross Unrealized Losses 12 months or longer	30	48
Available for sale, Fair Value Total	1,356	1,628
Available for sale, Gross Unrealized Losses Total	36	61
Held to maturity, Fair Value Less than 12 months	191
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	191
Held to maturity, Gross Unrealized Losses Total	1
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	5,570	2,152
Available for sale, Gross Unrealized Losses Less than 12 months	23	5
Available for sale, Fair Value 12 months or longer	318	506
Available for sale, Gross Unrealized Losses 12 months or longer	14	27
Available for sale, Fair Value Total	5,888	2,658
Available for sale, Gross Unrealized Losses Total	37	32
Held to maturity, Fair Value Less than 12 months	1,199	56
Held to maturity, Gross Unrealized Losses Less than 12 months	7	1
Held to maturity, Fair Value 12 months or longer	914	1,185
Held to maturity, Gross Unrealized Losses 12 months or longer	71	70
Held to maturity, Fair Value Total	2,113	1,241
Held to maturity, Gross Unrealized Losses Total	78	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	672	670
Available for sale, Gross Unrealized Losses Less than 12 months	1	3
Available for sale, Fair Value 12 months or longer	290	453
Available for sale, Gross Unrealized Losses 12 months or longer	12	24
Available for sale, Fair Value Total	962	1,123
Available for sale, Gross Unrealized Losses Total	13	27
Held to maturity, Fair Value Less than 12 months	801	56
Held to maturity, Gross Unrealized Losses Less than 12 months	5	1
Held to maturity, Fair Value 12 months or longer	914	956
Held to maturity, Gross Unrealized Losses 12 months or longer	71	67
Held to maturity, Fair Value Total	1,715	1,012
Held to maturity, Gross Unrealized Losses Total	76	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	604	973
Available for sale, Gross Unrealized Losses Less than 12 months	1	1
Available for sale, Fair Value 12 months or longer	28	53
Available for sale, Gross Unrealized Losses 12 months or longer	2	3
Available for sale, Fair Value Total	632	1,026
Available for sale, Gross Unrealized Losses Total	3	4
Held to maturity, Fair Value Less than 12 months	398	0
Held to maturity, Gross Unrealized Losses Less than 12 months	2	0
Held to maturity, Fair Value 12 months or longer	0	73
Held to maturity, Gross Unrealized Losses 12 months or longer	0	1
Held to maturity, Fair Value Total	398	73
Held to maturity, Gross Unrealized Losses Total	2	1
Non-US debt securities, government securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	2,863
Available for sale, Gross Unrealized Losses Less than 12 months	2
Available for sale, Fair Value 12 months or longer	0
Available for sale, Gross Unrealized Losses 12 months or longer	0
Available for sale, Fair Value Total	2,863
Available for sale, Gross Unrealized Losses Total	2
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	1,431	509
Available for sale, Gross Unrealized Losses Less than 12 months	19	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	1,431	509
Available for sale, Gross Unrealized Losses Total	19	1
Held to maturity, Fair Value Less than 12 months		0
Held to maturity, Gross Unrealized Losses Less than 12 months		0
Held to maturity, Fair Value 12 months or longer		156
Held to maturity, Gross Unrealized Losses 12 months or longer		2
Held to maturity, Fair Value Total		156
Held to maturity, Gross Unrealized Losses Total		2
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	2,463	685
Available for sale, Gross Unrealized Losses Less than 12 months	124	9
Available for sale, Fair Value 12 months or longer	1,103	1,152
Available for sale, Gross Unrealized Losses 12 months or longer	62	58
Available for sale, Fair Value Total	3,566	1,837
Available for sale, Gross Unrealized Losses Total	186	67
Collateralized mortgage obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,398	347
Available for sale, Gross Unrealized Losses Less than 12 months	70	1
Available for sale, Fair Value 12 months or longer	393	621
Available for sale, Gross Unrealized Losses 12 months or longer	10	14
Available for sale, Fair Value Total	1,791	968
Available for sale, Gross Unrealized Losses Total	80	15
Held to maturity, Fair Value Less than 12 months	641	120
Held to maturity, Gross Unrealized Losses Less than 12 months	29	1
Held to maturity, Fair Value 12 months or longer	108	153
Held to maturity, Gross Unrealized Losses 12 months or longer	13	11
Held to maturity, Fair Value Total	749	273
Held to maturity, Gross Unrealized Losses Total	42	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	1,259	302
Available for sale, Gross Unrealized Losses Less than 12 months	32	1
Available for sale, Fair Value 12 months or longer	33	33
Available for sale, Gross Unrealized Losses 12 months or longer	6	6
Available for sale, Fair Value Total	1,292	335
Available for sale, Gross Unrealized Losses Total	$ 38	$ 7