Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Investment banking	$ 97,988	$ 36,553
Brokerage	105,733	50,534
Management fees	7,417	8,708
Incentive income	16	546
Interest and dividends	25,954	5,089
Reimbursement from affiliates	377	1,652
Aircraft lease revenue	715	1,059
Reinsurance premiums	8,647	7,089
Other revenues	1,336	1,400
Consolidated Funds
Interest and dividends	3,196	1,994
Other revenues	5	347
Total revenues	251,384	114,971
Expenses
Employee compensation and benefits	135,140	76,673
Floor brokerage and trade execution	30,198	8,323
Underwriting expenses	4,063	0
Interest and dividends	24,540	9,930
Professional, advisory and other fees	7,024	5,816
Service fees	5,195	2,616
Communications	7,566	4,760
Occupancy and equipment	9,861	7,063
Depreciation and amortization	3,225	3,028
Client services and business development	8,231	7,762
Reinsurance claims, commissions and amortization of deferred acquisition costs	8,731	6,178
Other expenses	4,081	3,261
Consolidated Funds
Interest and dividends	1,911	3,983
Professional, advisory and other fees	212	392
Floor brokerage and trade execution	64	109
Other expenses	244	479
Total expenses	250,286	140,373
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	15,969	26,056
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	15,736	9,578
Net realized and unrealized gains (losses) on derivatives	2,475	3,865
Net gains (losses) on foreign currency transactions	(346)	(97)
Total other income (loss)	33,834	39,402
Income (loss) before income taxes	34,932	14,000
Income tax expense (benefit)	6,923	1,911
Net income (loss)	28,009	12,089
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	(11,156)	(9,105)
Net income (loss) attributable to Cowen Inc.	16,853	2,984
Preferred stock dividends	1,698	1,698
Net income (loss) attributable to Cowen Inc. common stockholders	$ 15,155	$ 1,286
Weighted average common shares outstanding:
Basic (in shares)	29,625	27,061
Diluted (in shares)	30,492	28,401
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ 0.51	$ 0.05
Earnings Per Share, Diluted (in dollars per share)	$ 0.50	$ 0.05