Discontinued Operations (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Discontinued Operations
Total net revenue		$ 28,699,000	$ 201,567,000	$ 270,172,000
Total expenses (excluding restructuring expense)		50,689,000	227,956,000	331,528,000
Subtotal		(21,990,000)	(26,389,000)	(61,356,000)
Restructuring expense		(50,830,000)	447,000	(7,094,000)
Loss from discontinued operations before income taxes		(72,820,000)	(25,942,000)	(68,450,000)
Income tax expense		185,000	1,802,000	1,925,000
Loss from discontinued operations, net of taxes		(73,005,000)	(27,744,000)	(70,375,000)
Other items reclassified from continuing operations
Discontinued Operations
Total net revenue		574,000	5,627,000	8,660,000
Total expenses (excluding restructuring expense)		5,752,000	34,532,000	92,828,000
Expenses, net of revenues		(5,178,000)	(28,905,000)	(84,168,000)
Investment Banking
Discontinued Operations
Total net revenue		15,056,000	27,441,000	26,610,000
Total expenses (excluding restructuring expense)		12,633,000	22,863,000	24,320,000
Expenses, net of revenues		2,423,000	4,578,000	2,290,000
MBS & Rates
Discontinued Operations
Total net revenue		(4,412,000)	40,638,000	103,858,000
Total expenses (excluding restructuring expense)		11,003,000	40,511,000	70,738,000
Expenses, net of revenues		(15,415,000)	127,000	33,120,000
Credit Products
Discontinued Operations
Total net revenue		13,049,000	74,432,000	71,056,000
Total expenses (excluding restructuring expense)		14,521,000	70,687,000	61,318,000
Expenses, net of revenues		(1,472,000)	3,745,000	9,738,000
ClearPoint
Discontinued Operations
Loss recognized from discontinued operations	1,100,000
Total net revenue		4,356,000	53,375,000	46,924,000
Total expenses (excluding restructuring expense)		6,611,000	59,265,000	50,610,000
Expenses, net of revenues		(2,255,000)	(5,890,000)	(3,686,000)
Equities Division [Member]
Discontinued Operations
Total net revenue		76,000	54,000	13,064,000
Total expenses (excluding restructuring expense)		169,000	98,000	31,714,000
Expenses, net of revenues		$ (93,000)	$ (44,000)	$ (18,650,000)