Investment Securities (Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	$ 9,415	$ 27,220
Available for sale, Gross Unrealized Losses Less than 12 months	34	580
Available for sale, Fair Value 12 months or longer	22,004	13,764
Available for sale, Gross Unrealized Losses 12 months or longer	533	567
Available for sale, Fair Value Total	31,419	40,984
Available for sale, Gross Unrealized Losses Total	567	1,147
Held to maturity, Fair Value Less than 12 months	940	7,813
Held to maturity, Gross Unrealized Losses Less than 12 months	8	480
Held to maturity, Fair Value 12 months or longer	6,288	1,068
Held to maturity, Gross Unrealized Losses 12 months or longer	271	54
Held to maturity, Fair Value Total	7,228	8,881
Held to maturity, Gross Unrealized Losses Total	279	534
Asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	3,241	7,540
Available for sale, Gross Unrealized Losses Less than 12 months	13	58
Available for sale, Fair Value 12 months or longer	9,971	9,002
Available for sale, Gross Unrealized Losses 12 months or longer	267	365
Available for sale, Fair Value Total	13,212	16,542
Available for sale, Gross Unrealized Losses Total	280	423
Held to maturity, Fair Value Less than 12 months	83	1,649
Held to maturity, Gross Unrealized Losses Less than 12 months	1	11
Held to maturity, Fair Value 12 months or longer	160	29
Held to maturity, Gross Unrealized Losses 12 months or longer	1	1
Held to maturity, Fair Value Total	243	1,678
Held to maturity, Gross Unrealized Losses Total	2	12
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	182
Available for sale, Gross Unrealized Losses Less than 12 months	0	1
Available for sale, Fair Value 12 months or longer	127	113
Available for sale, Gross Unrealized Losses 12 months or longer	1	1
Available for sale, Fair Value Total	127	295
Available for sale, Gross Unrealized Losses Total	1	2
Held to maturity, Fair Value Less than 12 months	0	4,571
Held to maturity, Gross Unrealized Losses Less than 12 months	0	448
Held to maturity, Fair Value 12 months or longer	4,765	0
Held to maturity, Gross Unrealized Losses 12 months or longer	237	0
Held to maturity, Fair Value Total	4,765	4,571
Held to maturity, Gross Unrealized Losses Total	237	448
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	2,484	10,562
Available for sale, Gross Unrealized Losses Less than 12 months	11	316
Available for sale, Fair Value 12 months or longer	7,865	2,389
Available for sale, Gross Unrealized Losses 12 months or longer	152	76
Available for sale, Fair Value Total	10,349	12,951
Available for sale, Gross Unrealized Losses Total	163	392
Asset-backed securities, student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	440	1,930
Available for sale, Gross Unrealized Losses Less than 12 months	4	16
Available for sale, Fair Value 12 months or longer	6,901	7,252
Available for sale, Gross Unrealized Losses 12 months or longer	154	252
Available for sale, Fair Value Total	7,341	9,182
Available for sale, Gross Unrealized Losses Total	158	268
Held to maturity, Fair Value Less than 12 months	0	1,352
Held to maturity, Gross Unrealized Losses Less than 12 months	0	10
Held to maturity, Fair Value 12 months or longer	160	0
Held to maturity, Gross Unrealized Losses 12 months or longer	1	0
Held to maturity, Fair Value Total	160	1,352
Held to maturity, Gross Unrealized Losses Total	1	10
Asset-backed securities, credit cards
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,268	3,714
Available for sale, Gross Unrealized Losses Less than 12 months	2	30
Available for sale, Fair Value 12 months or longer	1,664	161
Available for sale, Gross Unrealized Losses 12 months or longer	32	11
Available for sale, Fair Value Total	2,932	3,875
Available for sale, Gross Unrealized Losses Total	34	41
Held to maturity, Fair Value Less than 12 months		297
Held to maturity, Gross Unrealized Losses Less than 12 months		1
Held to maturity, Fair Value 12 months or longer		29
Held to maturity, Gross Unrealized Losses 12 months or longer		1
Held to maturity, Fair Value Total		326
Held to maturity, Gross Unrealized Losses Total		2
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	1,046	1,150
Available for sale, Gross Unrealized Losses 12 months or longer	74	91
Available for sale, Fair Value Total	1,046	1,150
Available for sale, Gross Unrealized Losses Total	74	91
Asset-backed securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,533	1,896
Available for sale, Gross Unrealized Losses Less than 12 months	7	12
Available for sale, Fair Value 12 months or longer	360	439
Available for sale, Gross Unrealized Losses 12 months or longer	7	11
Available for sale, Fair Value Total	1,893	2,335
Available for sale, Gross Unrealized Losses Total	14	23
Held to maturity, Fair Value Less than 12 months	83
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	83
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	3,073	3,074
Available for sale, Gross Unrealized Losses Less than 12 months	5	12
Available for sale, Fair Value 12 months or longer	510	424
Available for sale, Gross Unrealized Losses 12 months or longer	7	10
Available for sale, Fair Value Total	3,583	3,498
Available for sale, Gross Unrealized Losses Total	12	22
Held to maturity, Fair Value Less than 12 months	514	834
Held to maturity, Gross Unrealized Losses Less than 12 months	2	3
Held to maturity, Fair Value 12 months or longer	732	878
Held to maturity, Gross Unrealized Losses 12 months or longer	20	45
Held to maturity, Fair Value Total	1,246	1,712
Held to maturity, Gross Unrealized Losses Total	22	48
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	580	868
Available for sale, Gross Unrealized Losses Less than 12 months	1	2
Available for sale, Fair Value 12 months or longer	215	258
Available for sale, Gross Unrealized Losses 12 months or longer	2	7
Available for sale, Fair Value Total	795	1,126
Available for sale, Gross Unrealized Losses Total	3	9
Held to maturity, Fair Value Less than 12 months	460
Held to maturity, Gross Unrealized Losses Less than 12 months	1
Held to maturity, Fair Value 12 months or longer	732
Held to maturity, Gross Unrealized Losses 12 months or longer	20
Held to maturity, Fair Value Total	1,192
Held to maturity, Gross Unrealized Losses Total	21
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	501	551
Available for sale, Gross Unrealized Losses Less than 12 months	1	1
Available for sale, Fair Value 12 months or longer	0	16
Available for sale, Gross Unrealized Losses 12 months or longer	0	1
Available for sale, Fair Value Total	501	567
Available for sale, Gross Unrealized Losses Total	1	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	1,992	1,655
Available for sale, Gross Unrealized Losses Less than 12 months	3	9
Available for sale, Fair Value 12 months or longer	295	150
Available for sale, Gross Unrealized Losses 12 months or longer	5	2
Available for sale, Fair Value Total	2,287	1,805
Available for sale, Gross Unrealized Losses Total	8	11
Held to maturity, Fair Value Less than 12 months	54
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	54
Held to maturity, Gross Unrealized Losses Total	1
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	308	3,242
Available for sale, Gross Unrealized Losses Less than 12 months	3	113
Available for sale, Fair Value 12 months or longer	2,263	1,268
Available for sale, Gross Unrealized Losses 12 months or longer	69	85
Available for sale, Fair Value Total	2,571	4,510
Available for sale, Gross Unrealized Losses Total	72	198
Collateralized mortgage obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	309	1,581
Available for sale, Gross Unrealized Losses Less than 12 months	2	55
Available for sale, Fair Value 12 months or longer	863	510
Available for sale, Gross Unrealized Losses 12 months or longer	28	21
Available for sale, Fair Value Total	1,172	2,091
Available for sale, Gross Unrealized Losses Total	30	76
Held to maturity, Fair Value Less than 12 months	343	759
Held to maturity, Gross Unrealized Losses Less than 12 months	5	18
Held to maturity, Fair Value 12 months or longer	631	161
Held to maturity, Gross Unrealized Losses 12 months or longer	13	8
Held to maturity, Fair Value Total	974	920
Held to maturity, Gross Unrealized Losses Total	18	26
Other U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	1,039
Available for sale, Gross Unrealized Losses Less than 12 months	0	25
Available for sale, Fair Value 12 months or longer	405	58
Available for sale, Gross Unrealized Losses 12 months or longer	9	9
Available for sale, Fair Value Total	405	1,097
Available for sale, Gross Unrealized Losses Total	$ 9	$ 34