Supplemental Financial Information (Tables)

12 Months Ended

Dec. 31, 2013

Supplemental Financial Information [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

	Quarter Ended
	March 31, 2013			June 30, 2013		September 30, 2013			December 31, 2013
	(in thousands)
Total revenues	$	67,241		$	81,207	$	81,360		$	97,438
Net Income (loss) before income taxes	1,095			3,506		8,324			5,372
Income tax expense (benefit)	176			158		(46		)	169
Net income (loss) from continuing operations	919			3,348		8,370			5,203
Net Income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	3,495			2,255		4,759			2,684
Net income (loss) attributable to Cowen Group, Inc. stockholders	$	(2,576	)	$	1,093	$	3,611		$	2,519
Earnings (loss) per share:
Basic	$	(0.02	)	$	0.01	$	0.03		$	0.02
Diluted	$	(0.02	)	$	0.01	$	0.03		$	0.02
Weighted average number of common shares:
Basic	113,798			117,235		118,359			117,514
Diluted	113,798			120,901		122,708			123,573

	Quarter Ended
	March 31, 2012		June 30, 2012			September 30, 2012			December 31, 2012
	(in thousands)
Total revenues	$	57,480	$	59,470		$	57,598		$	65,932
Net Income (loss) before income taxes	6,378		(10,189		)	(11,455		)	(8,243		)
Income tax expense (benefit)	142		191			163			(48		)
Net income (loss) from continuing operations	6,236		(10,380		)	(11,618		)	(8,195		)
Net Income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	2,241		(2,434		)	(1,033		)	1,154
Net income (loss) attributable to Cowen Group, Inc. stockholders	$	3,995	$	(7,946	)	$	(10,585	)	$	(9,349	)
Earnings (loss) per share:
Basic	$	0.03	$	(0.07	)	$	(0.09	)	$	(0.08	)
Diluted	$	0.03	$	(0.07	)	$	(0.09	)	$	(0.08	)
Weighted average number of common shares:
Basic	114,281		114,561			114,989			113,939
Diluted	115,663		114,561			114,989			113,939