Financial Instruments Owned, At Fair Value And Financial Instruments Sold, But Not Yet Purchased, At Fair Value (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	$ 370,605,000,000		$ 370,605,000,000		$ 356,953,000,000
Financial instruments sold, but not yet purchased, at fair value	149,639,000,000		149,639,000,000		140,717,000,000
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	2,338,000,000	4,257,000,000	9,412,000,000	12,523,000,000
Trading Assets and Trading Liabilities (Textuals) [Abstract]
Available-for-sale securities substantially all of which is held within the firm's insurance subsidiaries included in Total Financial Instruments Owned, at Fair Value	3,480,000,000		3,480,000,000		3,670,000,000
Money market instruments held by William Street Funding Corporation (Funding Corp.) to support the William Street credit extension program included in commercial paper, certificates of deposit, time deposits and other money market instruments assets					4,060,000,000
Interest Rates [Member]
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	1,034,000,000	(2,836,000,000)	3,440,000,000	(4,768,000,000)
Credit [Member]
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	929,000,000	2,216,000,000	2,980,000,000	6,449,000,000
Foreign Exchange [Member]
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	(984,000,000)	3,601,000,000	(2,590,000,000)	7,040,000,000
Equity [Member]
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	1,024,000,000	580,000,000	3,874,000,000	1,961,000,000
Commodity [Member]
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	(71,000,000)	77,000,000	886,000,000	686,000,000
Other Trading [Member]
Gains and Losses from Market Making and Other Principal Transactions
Trading Activity, Gains and Losses, Net	406,000,000	619,000,000	822,000,000	1,155,000,000
Commercial paper, certificates of deposit, time deposits and other money market instruments [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	7,186,000,000		7,186,000,000		11,262,000,000
Financial instruments sold, but not yet purchased, at fair value	0		0		0
U.S. government and federal agency obligations [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	87,075,000,000		87,075,000,000		84,928,000,000
Financial instruments sold, but not yet purchased, at fair value	29,392,000,000		29,392,000,000		23,264,000,000
Non-U.S. government obligations [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	55,023,000,000		55,023,000,000		40,675,000,000
Financial instruments sold, but not yet purchased, at fair value	28,622,000,000		28,622,000,000		29,009,000,000
Loans and securities backed by commercial real estate [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	6,693,000,000		6,693,000,000		6,200,000,000
Financial instruments sold, but not yet purchased, at fair value	0		0		5,000,000
Loans and securities backed by residential real estate [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	7,716,000,000		7,716,000,000		9,404,000,000
Financial instruments sold, but not yet purchased, at fair value	12,000,000		12,000,000		6,000,000
Loan portfolios [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	1,238,000,000		1,238,000,000		1,438,000,000
Financial instruments sold, but not yet purchased, at fair value	0		0		0
Bank loans and bridge loans [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	18,927,000,000		18,927,000,000		18,039,000,000
Financial instruments sold, but not yet purchased, at fair value	1,823,000,000		1,823,000,000		1,487,000,000
Corporate Debt Securities [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	25,582,000,000		25,582,000,000		24,719,000,000
Financial instruments sold, but not yet purchased, at fair value	9,267,000,000		9,267,000,000		7,219,000,000
State and municipal obligations [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	3,328,000,000		3,328,000,000		2,792,000,000
Financial instruments sold, but not yet purchased, at fair value	0		0		0
Other debt obligations [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	2,554,000,000		2,554,000,000		3,232,000,000
Financial instruments sold, but not yet purchased, at fair value	4,000,000		4,000,000		0
Equities and convertible debentures [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	71,626,000,000		71,626,000,000		67,833,000,000
Financial instruments sold, but not yet purchased, at fair value	33,019,000,000		33,019,000,000		24,988,000,000
Commodities [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	10,133,000,000		10,133,000,000		13,138,000,000
Financial instruments sold, but not yet purchased, at fair value	8,000,000		8,000,000		9,000,000
Derivative [Member]
Fair Value of Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased
Financial instruments owned, at fair value (includes $57,687 and $51,010 pledged as collateral as of June 2011 and December 2010, respectively)	73,524,000,000		73,524,000,000		73,293,000,000
Financial instruments sold, but not yet purchased, at fair value	$ 47,492,000,000		$ 47,492,000,000		$ 54,730,000,000