Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues
Investment banking	$ 105,333	$ 71,762	$ 50,976
Brokerage	114,593	91,167	99,611
Management fees	37,303	38,116	52,466
Incentive income	12,586	5,411	3,265
Interest and dividends	39,454	24,608	22,306
Reimbursement from affiliates	9,161	5,239	4,322
Other revenues	5,418	3,668	1,583
Consolidated Funds
Interest and dividends	1,185	136	569
Other revenues	2,213	373	180
Total revenues	327,246	240,480	235,278
Expenses
Employee compensation and benefits	207,248	194,034	203,767
Floor brokerage and trade execution	16,935	14,684	16,475
Interest and dividends	27,299	12,137	9,233
Professional, advisory and other fees	14,625	16,339	33,702
Service fees	9,768	11,281	16,365
Communications	18,078	15,704	16,350
Occupancy and equipment	24,729	22,087	27,887
Depreciation and amortization	10,227	9,437	15,472
Client services and business development	17,353	14,069	16,725
Goodwill impairment	0	0	7,151
Other expenses	12,616	15,452	9,746
Consolidated Funds
Interest and dividends	345	22	147
Professional, advisory and other fees	1,157	1,361	2,136
Floor brokerage and trade execution	285	0	0
Other expenses	252	293	499
Total expenses	360,917	326,900	375,655
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	40,924	55,665	15,128
Bargain purchase gain	0	0	22,244
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	10,678	6,376	4,925
Net realized and unrealized gains (losses) on derivatives	365	877	(583)
Net gains (losses) on foreign currency transactions	1	(7)	53
Total other income (loss)	51,968	62,911	41,767
Income (loss) before income taxes	18,297	(23,509)	(98,610)
Income tax expense (benefit)	457	448	(20,073)
Net income (loss) from continuing operations	17,840	(23,957)	(78,537)
Net income (loss) from discontinued operations, net of tax	0	0	(23,646)
Net income (loss)	17,840	(23,957)	(102,183)
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	13,193	(72)	5,827
Net income (loss) attributable to Cowen Group, Inc. stockholders	$ 4,647	$ (23,885)	$ (108,010)
Weighted average common shares outstanding:
Basic (in shares)	116,703	114,400	95,532
Diluted (in shares)	121,117	114,400	95,532
Earnings (loss) per share:
Income (loss) from continuing operations, basic (in dollars per share)	$ 0.04	$ (0.21)	$ (0.88)
Income (loss) from discontinued operations, basic (in dollars per share)	$ 0.00	$ 0.00	$ (0.25)
Income (loss) from continuing operations, diluted (in dollars per share)	$ 0.04	$ (0.21)	$ (0.88)
Income (loss) from discontinued operations, diluted (in dollars per share)	$ 0.00	$ 0.00	$ (0.25)