Securities - Amortized Costs, Fair Value (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	$ 359,892	$ 358,940
Available-for-sale Securities, Gross Unrealized Gains	11,503	8,804
Available-for-sale Securities, Gross Unrealized Losses	250	2,963
Available-for-sale Securities	371,145	364,781
Held-to-maturity Securities, Amortized Cost	7	12
Held-to-maturity Securities, Gross unrealized gains	1	1
Held-to-maturity Securities, Gross unrealized losses	0	0
Held-to-maturity Securities, Fair Value	8	13
Accumulated Other-than-Temporary Impairment [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Gross Unrealized Losses		91
Equity securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,750	2,693
Available-for-sale Securities, Gross Unrealized Gains	21	14
Available-for-sale Securities, Gross Unrealized Losses	0	2
Available-for-sale Securities	2,771	2,705
Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	357,142	356,247
Available-for-sale Securities, Gross Unrealized Gains	11,482	8,790
Available-for-sale Securities, Gross Unrealized Losses	250	2,961
Available-for-sale Securities	368,374	362,076
Mortgage-backed securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	178,997	180,838
Available-for-sale Securities, Gross Unrealized Gains	7,291	6,015
Available-for-sale Securities, Gross Unrealized Losses	58	960
Available-for-sale Securities	186,230	185,893
US Government Corporations and Agencies Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	93,693	101,968
Available-for-sale Securities, Gross Unrealized Gains	4,708	5,141
Available-for-sale Securities, Gross Unrealized Losses	13	2
Available-for-sale Securities	98,388	107,107
Commercial mortgage
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	12,268	10,632
Available-for-sale Securities, Gross Unrealized Gains	948	650
Available-for-sale Securities, Gross Unrealized Losses	13	53
Available-for-sale Securities	13,203	11,229
U.S. Treasury and government agencies [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	12,022	8,184
Available-for-sale Securities, Gross Unrealized Gains	116	169
Available-for-sale Securities, Gross Unrealized Losses	8	2
Available-for-sale Securities	12,130	8,351
Obligations of U.S. states and municipalities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	19,876	15,404
Available-for-sale Securities, Gross Unrealized Gains	1,845	1,184
Available-for-sale Securities, Gross Unrealized Losses	10	48
Available-for-sale Securities	21,711	16,540
Certificates of Deposit [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,781	3,017
Available-for-sale Securities, Gross Unrealized Gains	4	0
Available-for-sale Securities, Gross Unrealized Losses	2	0
Available-for-sale Securities	2,783	3,017
Non-U.S. government debt securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	65,168	44,944
Available-for-sale Securities, Gross Unrealized Gains	901	402
Available-for-sale Securities, Gross Unrealized Losses	25	81
Available-for-sale Securities	66,044	45,265
Corporate Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	37,999	63,607
Available-for-sale Securities, Gross Unrealized Gains	694	216
Available-for-sale Securities, Gross Unrealized Losses	84	1,647
Available-for-sale Securities	38,609	62,176
US Government-sponsored Enterprises Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities	84,000	89,300
Collateralized Loan Obligations [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	27,483	24,474
Available-for-sale Securities, Gross Unrealized Gains	465	553
Available-for-sale Securities, Gross Unrealized Losses	52	166
Available-for-sale Securities	27,896	24,861
Other, Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	12,816	15,779
Available-for-sale Securities, Gross Unrealized Gains	166	251
Available-for-sale Securities, Gross Unrealized Losses	11	57
Available-for-sale Securities	12,971	15,973
Residential Mortgage Backed Securities [Member] \| Prime and Alt-A [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	1,853	2,170
Available-for-sale Securities, Gross Unrealized Gains	83	54
Available-for-sale Securities, Gross Unrealized Losses	3	218
Available-for-sale Securities	1,933	2,006
Residential Mortgage Backed Securities [Member] \| Subprime [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	825	1
Available-for-sale Securities, Gross Unrealized Gains	28	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	853	1
Residential Mortgage Backed Securities [Member] \| Foreign Mortgage-backed Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	70,358	66,067
Available-for-sale Securities, Gross Unrealized Gains	1,524	170
Available-for-sale Securities, Gross Unrealized Losses	29	687
Available-for-sale Securities	$ 71,853	$ 65,550

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Publisher FASB

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-Number 115

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Number 115

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details

- Definition

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Paragraph 1

-Subparagraph (SX 210.7-03.1)

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-Publisher AICPA

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-Paragraph 5

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 4

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.6)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

+ References+ Details

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

+ References+ Details