Securities - Amortized Costs, Fair Value (Details 1) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	$ 355,509	$ 359,892
Available-for-sale Securities, Gross Unrealized Gains	10,595	11,503
Available-for-sale Securities, Gross Unrealized Losses	367	250
Available-for-sale Securities	365,737	371,145
Held-to-maturity Securities, Amortized Cost	7	7
Held-to-maturity Securities, Gross unrealized gains	0	1
Held-to-maturity Securities, Gross unrealized losses	0	0
Held-to-maturity Securities, Fair Value	7	8
US Government Corporations and Agencies Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	100,298	93,693
Available-for-sale Securities, Gross Unrealized Gains	4,097	4,708
Available-for-sale Securities, Gross Unrealized Losses	131	13
Available-for-sale Securities	104,264	98,388
Prime and Alt-A \| Residential and commercial mortgage securitizations
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	1,591	1,853
Available-for-sale Securities, Gross Unrealized Gains	66	83
Available-for-sale Securities, Gross Unrealized Losses	4	3
Available-for-sale Securities	1,653	1,933
Subprime \| Residential and commercial mortgage securitizations
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	738	825
Available-for-sale Securities, Gross Unrealized Gains	19	28
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	757	853
Foreign Mortgage-backed Securities \| Residential and commercial mortgage securitizations
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	63,844	70,358
Available-for-sale Securities, Gross Unrealized Gains	1,493	1,524
Available-for-sale Securities, Gross Unrealized Losses	11	29
Available-for-sale Securities	65,326	71,853
Commercial Mortgage Backed Securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	11,976	12,268
Available-for-sale Securities, Gross Unrealized Gains	868	948
Available-for-sale Securities, Gross Unrealized Losses	7	13
Available-for-sale Securities	12,837	13,203
Collateralized Mortgage Backed Securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	178,447	178,997
Available-for-sale Securities, Gross Unrealized Gains	6,543	7,291
Available-for-sale Securities, Gross Unrealized Losses	153	58
Available-for-sale Securities	184,837	186,230
US Treasury and Government
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	11,804	12,022
Available-for-sale Securities, Gross Unrealized Gains	173	116
Available-for-sale Securities, Gross Unrealized Losses	47	8
Available-for-sale Securities	11,930	12,130
US States and Political Subdivisions Debt Securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	19,401	19,876
Available-for-sale Securities, Gross Unrealized Gains	1,630	1,845
Available-for-sale Securities, Gross Unrealized Losses	53	10
Available-for-sale Securities	20,978	21,711
Certificates of Deposit
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,373	2,781
Available-for-sale Securities, Gross Unrealized Gains	7	4
Available-for-sale Securities, Gross Unrealized Losses	1	2
Available-for-sale Securities	2,379	2,783
Foreign Government Debt Securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	69,445	65,168
Available-for-sale Securities, Gross Unrealized Gains	948	901
Available-for-sale Securities, Gross Unrealized Losses	26	25
Available-for-sale Securities	70,367	66,044
Corporate Debt Securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	32,616	37,999
Available-for-sale Securities, Gross Unrealized Gains	686	694
Available-for-sale Securities, Gross Unrealized Losses	63	84
Available-for-sale Securities	33,239	38,609
Collateralized loan obligations
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	26,997	27,483
Available-for-sale Securities, Gross Unrealized Gains	381	465
Available-for-sale Securities, Gross Unrealized Losses	19	52
Available-for-sale Securities	27,359	27,896
Other Debt Obligations
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	11,968	12,816
Available-for-sale Securities, Gross Unrealized Gains	211	166
Available-for-sale Securities, Gross Unrealized Losses	5	11
Available-for-sale Securities	12,174	12,971
Debt Securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	353,051	357,142
Available-for-sale Securities, Gross Unrealized Gains	10,579	11,482
Available-for-sale Securities, Gross Unrealized Losses	367	250
Available-for-sale Securities	363,263	368,374
Equity securities
Amortized costs and estimated fair values
Available-for-sale Securities, Amortized Cost	2,458	2,750
Available-for-sale Securities, Gross Unrealized Gains	16	21
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	2,474	2,771
US Government-sponsored Enterprises Debt Securities [Member]
Amortized costs and estimated fair values
Available-for-sale Securities	$ 90,300	$ 84,000

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

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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

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

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

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-Paragraph 4

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-Paragraph 1

-Subparagraph (SX 210.9-03.6)

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+ 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