Fair Value Option (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended						3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Other Guarantees and Commitments	Dec. 31, 2012 Other Guarantees and Commitments	Mar. 31, 2013 Principal transactions	Mar. 31, 2012 Principal transactions	Mar. 31, 2013 Other income	Mar. 31, 2012 Other income	Mar. 31, 2013 Letters of Credit Hedged by Derivative Transactions Other Guarantees and Commitments	Dec. 31, 2012 Letters of Credit Hedged by Derivative Transactions Other Guarantees and Commitments	Mar. 31, 2013 Debit Valuation Adjustment	Mar. 31, 2012 Debit Valuation Adjustment
Changes in fair value under the fair value option election
Federal funds sold and securities purchased under resale agreements	$ (71)	$ (48)			$ (71)	$ (48)	$ 0	$ 0
Securities borrowed	26	14			26	14	0	0
Trading assets:
Debt and equity instruments, excluding loans	259	367			256	364	3	3
Loans reported as trading assets:
Changes in instrument-specific credit risk	340	494			328	476	12	18
Other changes in fair value	968	1,325			16	(252)	952	1,577
Loans:
Changes in instrument-specific credit risk	(5)	0			(5)	0	0	0
Other changes in fair value	0	25			0	25	0	0
Other assets	(70)	(194)			(1)	0	(69)	(194)
Deposits	78	(160)			78	(160)	0	0
Federal funds purchased and securities loaned or sold under repurchase agreements	4	2			4	2	0	0
Other borrowed funds	(354)	(475)			(354)	(475)	0	0
Trading liabilities	(18)	9			(18)	9	0	0
Beneficial interests issued by consolidated VIEs	(28)	(6)			(28)	(6)	0	0
Other liabilities	(1)	0			0	0	(1)	0
Long-term debt:
Changes in instrument-specific credit risk related to structured notes	33	(419)			33	(419)	0	0			131	(468)
Other changes in fair value	(31)	(705)			(31)	(705)	0	0
Fair Value Option - Supplemental Information
Guarantor Obligations, Maximum Exposure, Undiscounted			6,646	6,780					4,600	4,500
Guarantor Obligations, Current Carrying Value			$ (73)	$ (75)					$ (72)	$ (75)