Investment Securities - Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	$ 7,819	$ 8,532
Available for sale, Gross Unrealized Losses Less than 12 months	41	39
Available for sale, Fair Value 12 months or longer	13,762	16,983
Available for sale, Gross Unrealized Losses 12 months or longer	300	385
Available for sale, Fair Value Total	21,581	25,515
Available for sale, Gross Unrealized Losses Total	341	424
Held to maturity, Fair Value Less than 12 months	3,482	2,608
Held-to-maturity, Gross, Less than 12 Months	21	13
Held to maturity, Fair Value 12 months or longer	4,197	6,220
Held to maturity, Gross Unrealized Losses 12 months or longer	80	177
Held to maturity, Fair Value Total	7,679	8,828
Held to maturity, Gross Unrealized Losses Total	101	190
Asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	2,284	2,364
Available for sale, Gross Unrealized Losses Less than 12 months	18	17
Available for sale, Fair Value 12 months or longer	7,662	7,982
Available for sale, Gross Unrealized Losses 12 months or longer	193	207
Available for sale, Fair Value Total	9,946	10,346
Available for sale, Gross Unrealized Losses Total	211	224
Held to maturity, Fair Value Less than 12 months	631	904
Held-to-maturity, Gross, Less than 12 Months	3	4
Held to maturity, Fair Value 12 months or longer	232	192
Held to maturity, Gross Unrealized Losses 12 months or longer	2	1
Held to maturity, Fair Value Total	863	1,096
Held to maturity, Gross Unrealized Losses Total	5	5
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	158	167
Available for sale, Gross Unrealized Losses 12 months or longer	1	1
Available for sale, Fair Value Total	158	167
Available for sale, Gross Unrealized Losses Total	1	1
Held to maturity, Fair Value Less than 12 months	2,062	76
Held-to-maturity, Gross, Less than 12 Months	13	1
Held to maturity, Fair Value 12 months or longer	2,981	4,891
Held to maturity, Gross Unrealized Losses 12 months or longer	56	146
Held to maturity, Fair Value Total	5,043	4,967
Held to maturity, Gross Unrealized Losses Total	69	147
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	1,565	2,569
Available for sale, Gross Unrealized Losses Less than 12 months	8	9
Available for sale, Fair Value 12 months or longer	4,373	6,466
Available for sale, Gross Unrealized Losses 12 months or longer	58	118
Available for sale, Fair Value Total	5,938	9,035
Available for sale, Gross Unrealized Losses Total	66	127
Asset-backed securities, student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,440	1,473
Available for sale, Gross Unrealized Losses Less than 12 months	13	15
Available for sale, Fair Value 12 months or longer	4,875	5,025
Available for sale, Gross Unrealized Losses 12 months or longer	100	109
Available for sale, Fair Value Total	6,315	6,498
Available for sale, Gross Unrealized Losses Total	113	124
Held to maturity, Fair Value Less than 12 months	631	780
Held-to-maturity, Gross, Less than 12 Months	3	3
Held to maturity, Fair Value 12 months or longer	232	192
Held to maturity, Gross Unrealized Losses 12 months or longer	2	1
Held to maturity, Fair Value Total	863	972
Held to maturity, Gross Unrealized Losses Total	5	4
Asset-backed securities, credit cards
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	344
Available for sale, Gross Unrealized Losses Less than 12 months	0	1
Available for sale, Fair Value 12 months or longer	1,287	1,270
Available for sale, Gross Unrealized Losses 12 months or longer	34	33
Available for sale, Fair Value Total	1,287	1,614
Available for sale, Gross Unrealized Losses Total	34	34
Held to maturity, Fair Value Less than 12 months		124
Held-to-maturity, Gross, 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		124
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	860	896
Available for sale, Gross Unrealized Losses 12 months or longer	52	56
Available for sale, Fair Value Total	860	896
Available for sale, Gross Unrealized Losses Total	52	56
Asset-backed securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	844	547
Available for sale, Gross Unrealized Losses Less than 12 months	5	1
Available for sale, Fair Value 12 months or longer	640	791
Available for sale, Gross Unrealized Losses 12 months or longer	7	9
Available for sale, Fair Value Total	1,484	1,338
Available for sale, Gross Unrealized Losses Total	12	10
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	2,237	1,931
Available for sale, Gross Unrealized Losses Less than 12 months	6	6
Available for sale, Fair Value 12 months or longer	439	498
Available for sale, Gross Unrealized Losses 12 months or longer	4	5
Available for sale, Fair Value Total	2,676	2,429
Available for sale, Gross Unrealized Losses Total	10	11
Held to maturity, Fair Value Less than 12 months	517	1,206
Held-to-maturity, Gross, Less than 12 Months	2	4
Held to maturity, Fair Value 12 months or longer	569	590
Held to maturity, Gross Unrealized Losses 12 months or longer	17	19
Held to maturity, Fair Value Total	1,086	1,796
Held to maturity, Gross Unrealized Losses Total	19	23
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	1,097	1,350
Available for sale, Gross Unrealized Losses Less than 12 months	3	2
Available for sale, Fair Value 12 months or longer	146	170
Available for sale, Gross Unrealized Losses 12 months or longer	1	2
Available for sale, Fair Value Total	1,243	1,520
Available for sale, Gross Unrealized Losses Total	4	4
Held to maturity, Fair Value Less than 12 months	517	507
Held-to-maturity, Gross, Less than 12 Months	2	3
Held to maturity, Fair Value 12 months or longer	569	590
Held to maturity, Gross Unrealized Losses 12 months or longer	17	19
Held to maturity, Fair Value Total	1,086	1,097
Held to maturity, Gross Unrealized Losses Total	19	22
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	499
Available for sale, Gross Unrealized Losses Less than 12 months	1
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	499
Available for sale, Gross Unrealized Losses Total	1
Held to maturity, Fair Value Less than 12 months		699
Held-to-maturity, Gross, 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		699
Held to maturity, Gross Unrealized Losses Total		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	641	581
Available for sale, Gross Unrealized Losses Less than 12 months	2	4
Available for sale, Fair Value 12 months or longer	293	328
Available for sale, Gross Unrealized Losses 12 months or longer	3	3
Available for sale, Fair Value Total	934	909
Available for sale, Gross Unrealized Losses Total	5	7
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	980	610
Available for sale, Gross Unrealized Losses Less than 12 months	6	3
Available for sale, Fair Value 12 months or longer	776	1,315
Available for sale, Gross Unrealized Losses 12 months or longer	31	34
Available for sale, Fair Value Total	1,756	1,925
Available for sale, Gross Unrealized Losses Total	37	37
Collateralized mortgage obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	747	731
Available for sale, Gross Unrealized Losses Less than 12 months	2	2
Available for sale, Fair Value 12 months or longer	208	311
Available for sale, Gross Unrealized Losses 12 months or longer	5	10
Available for sale, Fair Value Total	955	1,042
Available for sale, Gross Unrealized Losses Total	7	12
Held to maturity, Fair Value Less than 12 months	272	422
Held-to-maturity, Gross, Less than 12 Months	3	4
Held to maturity, Fair Value 12 months or longer	415	547
Held to maturity, Gross Unrealized Losses 12 months or longer	5	11
Held to maturity, Fair Value Total	687	969
Held to maturity, Gross Unrealized Losses Total	8	15
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	327
Available for sale, Gross Unrealized Losses Less than 12 months	0	2
Available for sale, Fair Value 12 months or longer	146	244
Available for sale, Gross Unrealized Losses 12 months or longer	8	10
Available for sale, Fair Value Total	146	571
Available for sale, Gross Unrealized Losses Total	8	12
U.S. equity securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	6
Available for sale, Gross Unrealized Losses Less than 12 months	1
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	6
Available for sale, Gross Unrealized Losses Total	$ 1

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

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This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

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Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity that have been in a continuous loss position for twelve months or longer.

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