Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues
Investment banking	$ 769,486	$ 375,025	$ 357,222
Brokerage	572,548	402,747	413,582
Management fees	47,515	32,608	29,658
Incentive income	592	1,547	3,117
Interest and dividends	187,459	174,913	108,009
Reimbursement from affiliates	1,048	1,026	1,038
Operating Leases, Income Statement, Lease Revenue	0	0	1,852
Reinsurance premiums	30,147	46,335	38,096
Other revenues	8,621	5,433	4,504
Consolidated Funds
Interest and dividends	5,218	9,772	9,816
Other revenues	670	37	22
Total revenues	1,623,304	1,049,443	966,916
Interest and dividends expense	187,725	168,628	104,116
Total net revenues	1,435,579	880,815	862,800
Expenses
Employee compensation and benefits	860,531	535,772	512,627
Brokerage and trade execution costs	139,034	103,235	109,399
Underwriting expenses	22,565	15,067	15,282
Professional, advisory and other fees	59,990	48,385	40,957
Service fees	25,378	23,707	20,198
Communications	32,593	31,894	30,801
Occupancy and equipment	36,559	39,726	41,602
Depreciation and amortization	22,677	20,460	12,436
Client services and business development	20,526	50,371	35,927
Goodwill Impairment	0	4,100	0
Reinsurance claims, commissions and amortization of deferred acquisition costs	33,905	44,070	41,086
Other expenses	33,195	23,114	22,014
Consolidated Funds
Interest and dividends	2,064	4,602	6,534
Professional, advisory and other fees	2,087	2,426	938
Brokerage and trade execution costs	37	122	256
Other expenses	1,221	1,813	887
Total expenses	1,292,362	948,864	890,944
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	175,877	80,409	68,043
Gain/(loss) on debt extinguishment	2,719	0	(556)
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	(26,188)	59,384	46,656
Net realized and unrealized gains (losses) on derivatives	1,850	(1,003)	9,408
Net gains (losses) on foreign currency transactions	(38)	(18)	191
Total other income (loss)	154,220	138,772	123,742
Income (loss) before income taxes	297,437	70,723	95,598
Income tax expense (benefit)	90,373	14,853	15,719
Net income (loss)	207,064	55,870	79,879
Net Income (Loss) Attributable to Noncontrolling Interest	(9,299)	31,239	37,060
Net income (loss) attributable to Cowen Inc.	216,363	24,631	42,819
Preferred stock dividends	6,792	6,792	6,792
Net income (loss) attributable to Cowen Inc. common stockholders	$ 209,571	$ 17,839	$ 36,027
Weighted average common shares outstanding:
Basic (in shares)	27,790	29,525	29,545
Diluted (in shares)	29,519	31,286	30,735
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ 7.54	$ 0.60	$ 1.22
Earnings Per Share, Diluted (in dollars per share)	$ 7.10	$ 0.57	$ 1.17