FAIR VALUE MEASUREMENT (Details 3) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011
Total return swaps and other
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Net realized/unrealized gains (losses) included in principal transactions, assets				$ (600,000,000)
Federal funds sold and securities borrowed or purchased under agreements to resell
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period				0	(1,500,000,000)
Net transfers from Level 3 to Level 2				0	1,400,000,000
Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period	(3,400,000,000)	(3,800,000,000)		(2,500,000,000)	(800,000,000)
Purchases of securities	2,800,000,000			9,800,000,000
Net settlements	4,800,000,000			11,300,000,000
Derivatives
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period				(1,400,000,000)
Net realized/unrealized gains (losses) included in principal transactions, assets				(1,500,000,000)
Net settlements					(1,200,000,000)
Increase (decrease) in level 3 of credit derivatives				(1,400,000,000)	(2,100,000,000)
Losses on bespoke CDO and index CDO positions due to credit spreads widening				300,000,000
Gains on index positions classified as Level 2				200,000,000
Investments:
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period	(2,600,000,000)	(2,700,000,000)		(3,600,000,000)	(600,000,000)
Net settlements	0		(800,000,000)
Mortgage servicing rights
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period	(600,000,000)			(500,000,000)
Net realized/ unrealized gains (losses) included in other revenue, assets	(480,000,000)			(293,000,000)
Net settlements				377,000,000
Trading Securities and Loans
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Trading securities for which there were a reduced number of contributors to external pricing services	400,000,000			600,000,000
Long-term debt
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period	(600,000,000)	(1,500,000,000)		(1,000,000,000)	(1,500,000,000)
Net settlements	900,000,000	1,500,000,000		1,300,000,000	1,700,000,000
Issuance, assets	900,000,000			1,200,000,000
Increase (decrease) in level 3 of Long-term debt due to scheduled termination of a structured transaction	(400,000,000)	(1,200,000,000)		(400,000,000)	(1,200,000,000)
Structured notes
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Net transfers from Level 3 to Level 2	500,000,000			900,000,000
Mortgage-backed securities | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Securities reclassified to Trading	0		2,800,000,000	0
Mortgage-backed securities | Investments:
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Net transfers from Level 3 to Level 2	0	1,000,000,000
Prime | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Securities reclassified to Trading	0		1,000,000,000	0
Alt-A | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Securities reclassified to Trading	0		1,500,000,000	0
Subprime | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Securities reclassified to Trading	0		200,000,000	0
Commercial | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Securities reclassified to Trading	0		100,000,000	0
State and municipal securities | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Securities reclassified to Trading	0		900,000,000	0
Corporate | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Purchases of securities	0	700,000,000		0	2,200,000,000
Securities reclassified to Trading	0		300,000,000	0
Increase (decrease) in investments due to pay downs and sales	0	(800,000,000)		0	(2,100,000,000)
Asset-backed securities | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Purchases of securities	1,000,000,000	2,400,000,000		3,700,000,000	3,500,000,000
Sales of securities	1,200,000,000			4,300,000,000
Securities reclassified to Trading	0		200,000,000	0
Increase (decrease) in investments due to pay downs and sales	0	(2,000,000,000)		0	(3,900,000,000)
Non-marketable equity securities | Investments:
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period	0	(1,300,000,000)		0	1,200,000,000
Purchases of securities				0	3,300,000,000
Net settlements		(800,000,000)			(800,000,000)
Sales of securities	1,500,000,000			1,500,000,000
Increase (decrease) in investments due to pay downs and sales	0	(300,000,000)
Increase (decrease) in level 3 of non-marketable equity securities due to sales of investments in private equity and hedge funds					(1,100,000,000)
Reclassification of debt securities from held-to-maturity to trading account assets | Trading account assets
Fair Value Asset and Liabilities Measured on Recurring Basis Unobservable Input Changes
Increase (decrease) in Level 3 asset balance during period				$ 0	$ 4,300,000,000