Fair Value Option (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended						3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Other Guarantees and Commitments	Dec. 31, 2011 Other Guarantees and Commitments	Mar. 31, 2012 Principal transactions	Mar. 31, 2011 Principal transactions	Mar. 31, 2012 Other income	Mar. 31, 2011 Other income	Mar. 31, 2012 Letters Of Credit Hedged By Derivative Transactions [Member] Other Guarantees and Commitments	Dec. 31, 2011 Letters Of Credit Hedged By Derivative Transactions [Member] Other Guarantees and Commitments	Mar. 31, 2012 Debit Valuation Adjustment [Member]	Mar. 31, 2011 Debit Valuation Adjustment [Member]
Changes in fair value under the fair value option election
Federal funds sold and securities purchased under resale agreements	$ (48)	$ (118)			$ (48)	$ (118)	$ 0	$ 0
Securities borrowed	14	9			14	9	0	0
Trading assets:
Debt and equity instruments, excluding loans	367	167			364	164	3	3
Loans reported as trading assets:
Changes in instrument-specific credit risk	494	480			476	480	18	0
Other changes in fair value	1,325	848			(252)	125	1,577	723
Loans:
Changes in instrument-specific credit risk	0	(6)			0	(6)	0	0
Other changes in fair value	25	143			25	143	0	0
Other assets	(194)	0			0	0	(194)	0
Deposits	(160)	(17)			(160)	(17)	0	0
Federal funds purchased and securities loaned or sold under repurchase agreements	2	35			2	35	0	0
Other borrowed funds	(475)	217			(475)	217	0	0
Trading liabilities	9	(3)			9	(3)	0	0
Beneficial interests issued by consolidated VIEs	(6)	(34)			(6)	(34)	0	0
Other liabilities	0	(5)			0	(3)	0	(2)
Long-term debt:
Changes in instrument-specific credit risk	(419)	54			(419)	54	0	0
Other changes in fair value	(705)	(24)			(705)	(24)	0	0
Fair Value Option - Supplemental Information
Changes in instrument-specific credit risk related to structured notes											(468)	23
Contractual amount of letters of credit for which fair value option was elected			6,206	6,321					3,900	3,900
Carrying value of letters of credit			$ (80)	$ (5)					$ (80)	$ (5)