Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Investment banking	$ 375,025	$ 357,222	$ 223,614
Brokerage	402,747	413,582	293,610
Management fees	32,608	29,658	33,245
Incentive income	1,547	3,117	5,383
Interest and dividends	174,913	108,009	49,440
Reimbursement from affiliates	1,026	1,038	2,860
Aircraft lease revenue	0	1,852	3,751
Reinsurance premiums	46,335	38,096	30,996
Other revenues	5,433	4,504	8,561
Consolidated Funds
Interest and dividends	9,772	9,816	5,870
Other revenues	37	22	1,451
Total revenues	1,049,443	966,916	658,781
Interest and dividends expense	168,628	104,116	60,949
Total net revenues	880,815	862,800	597,832
Expenses
Employee compensation and benefits	535,772	512,627	404,087
Brokerage and trade execution costs	103,235	109,399	75,601
Underwriting expenses	15,067	15,282	0
Professional, advisory and other fees	48,385	40,957	31,942
Service fees	23,707	20,198	14,999
Communications	31,894	30,801	23,460
Occupancy and equipment	39,726	41,602	35,184
Depreciation and amortization	20,460	12,436	13,078
Client services and business development	50,371	35,927	28,327
Goodwill Impairment	4,100	0	0
Reinsurance claims, commissions and amortization of deferred acquisition costs	44,070	41,086	30,486
Restructuring Costs	0	0	8,763
Other expenses	23,114	22,014	18,196
Consolidated Funds
Interest and dividends	4,602	6,534	9,836
Professional, advisory and other fees	2,426	938	1,145
Brokerage and trade execution costs	122	256	318
Other expenses	1,813	887	1,227
Total expenses	948,864	890,944	696,649
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	80,409	68,043	76,179
Goodwill	0	0	6,914
Gain (loss) on debt extinguishment	0	(556)	(16,039)
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	59,384	46,656	19,660
Net realized and unrealized gains (losses) on derivatives	(1,003)	9,408	19,476
Net gains (losses) on foreign currency transactions	(18)	191	(411)
Total other income (loss)	138,772	123,742	105,779
Income (loss) before income taxes	70,723	95,598	6,962
Income tax expense (benefit)	14,853	15,719	44,053
Net income (loss)	55,870	79,879	(37,091)
Net Income (Loss) Attributable to Noncontrolling Interest	31,239	37,060	23,791
Net income (loss) attributable to Cowen Inc.	24,631	42,819	(60,882)
Preferred stock dividends	6,792	6,792	6,792
Net income (loss) attributable to Cowen Inc. common stockholders	$ 17,839	$ 36,027	$ (67,674)
Weighted average common shares outstanding:
Basic (in shares)	29,525	29,545	29,492
Diluted (in shares)	31,286	30,735	29,492
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ 0.60	$ 1.22	$ (2.29)
Earnings Per Share, Diluted (in dollars per share)	$ 0.57	$ 1.17	$ (2.29)