Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues
Investment banking	$ 17,166	$ 15,630
Brokerage	26,600	24,013
Management fees	9,493	9,717
Incentive income	2,611	691
Interest and dividends	9,321	5,372
Reimbursement from affiliates	1,485	1,045
Other revenues	478	867
Consolidated Funds
Interest and dividends	12	61
Other revenues	75	84
Total revenues	67,241	57,480
Expenses
Employee compensation and benefits	44,223	46,683
Floor brokerage and trade execution	4,478	3,752
Interest and dividends	6,418	1,724
Professional, advisory and other fees	3,853	3,925
Service fees	2,577	2,237
Communications	4,774	3,401
Occupancy and equipment	5,719	5,242
Depreciation and amortization	2,553	2,155
Client services and business development	4,099	3,826
Other expenses	3,984	3,419
Consolidated Funds
Interest and dividends	0	16
Professional, advisory and other fees	396	288
Other expenses	38	71
Total expenses	83,112	76,739
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	11,807	19,671
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	5,070	5,964
Net realized and unrealized gains (losses) on derivatives	304	40
Net gains (losses) on foreign currency transactions	(215)	(38)
Total other income (loss)	16,966	25,637
Income (loss) before income taxes	1,095	6,378
Income tax expense (benefit)	176	142
Net income (loss)	919	6,236
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries	3,495	2,241
Net income (loss) attributable to Cowen Group, Inc. stockholders	$ (2,576)	$ 3,995
Weighted average common shares outstanding:
Basic (in shares)	113,798	114,281
Diluted (in shares)	113,798	115,663
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.02)	$ 0.03
Diluted (in dollars per share)	$ (0.02)	$ 0.03