Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Investment banking	$ 35,287	$ 68,518	$ 61,434	$ 133,751
Brokerage	47,100	34,957	98,035	70,411
Management fees	10,649	10,266	21,679	20,650
Incentive income	428	(2,100)	1,539	272
Interest and dividends	4,105	3,159	7,758	6,242
Reimbursement from affiliates	2,241	3,502	6,128	7,144
Aircraft lease revenue	1,982	0	1,982	0
Other revenue	13,346	704	16,071	1,372
Consolidated Funds
Interest and dividends	1,538	196	2,614	440
Other revenues	555	406	1,030	420
Total revenues	117,231	119,608	218,270	240,702
Expenses
Employee compensation and benefits	55,627	75,328	118,808	171,192
Floor brokerage and trade execution	7,872	6,100	15,663	12,003
Interest and dividends	6,944	6,095	14,254	11,874
Professional, advisory and other fees	5,686	5,354	11,280	10,482
Service fees	2,075	1,674	4,259	3,560
Communications	4,529	3,193	8,668	6,835
Occupancy and equipment	7,873	6,910	15,878	13,738
Depreciation and amortization	3,413	2,145	6,480	4,283
Client services and business development	6,946	6,714	13,986	13,184
Other Expenses	14,618	2,849	20,430	7,659
Consolidated Funds
Interest and dividends	1,507	283	2,627	492
Professional, advisory and other fees	320	212	622	302
Floor brokerage and trade execution	111	56	133	66
Other expenses	205	83	577	132
Total expenses	117,726	116,996	233,665	255,802
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	(20,218)	9,070	(17,030)	48,061
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	(23,606)	3,020	(26,298)	7,740
Net realized and unrealized gains (losses) on derivatives	5,055	(723)	8,157	(326)
Net gains (losses) on foreign currency transactions	111	(1)	98	(32)
Total other income (loss)	(38,658)	11,366	(35,073)	55,443
Income (loss) before income taxes	(39,153)	13,978	(50,468)	40,343
Income tax expense (benefit)	(11,992)	3,346	(15,312)	10,293
Net income (loss)	(27,161)	10,632	(35,156)	30,050
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	16,705	(3,916)	21,002	(6,636)
Net income (loss) attributable to Cowen Group, Inc.	(10,456)	6,716	(14,154)	23,414
Preferred stock dividends	1,698	755	3,396	755
Net income (loss) attributable to Cowen Group, Inc. common stockholders	$ (12,154)	$ 5,961	$ (17,550)	$ 22,659
Weighted average common shares outstanding:
Basic (in shares)	107,471	111,915	106,918	111,987
Diluted (in shares)	107,471	118,226	106,918	118,316
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ (0.11)	$ 0.05	$ (0.16)	$ 0.20
Earnings Per Share, Diluted (in dollars per share)	$ (0.11)	$ 0.05	$ (0.16)	$ 0.19