Consolidated Statements of Operations - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Investment banking	$ 77,292,000	$ 81,923,000	$ 272,103,000	$ 264,737,000
Brokerage	93,995,000	92,035,000	302,840,000	301,053,000
Management fees	7,300,000	7,546,000	21,480,000	22,336,000
Incentive income	701,000	33,000	724,000	97,000
Interest and dividends	60,707,000	26,448,000	129,846,000	77,511,000
Reimbursement from affiliates	238,000	353,000	780,000	1,066,000
Aircraft lease revenue	0	375,000	0	1,509,000
Reinsurance premiums	8,146,000	8,378,000	29,068,000	26,251,000
Other revenues	1,237,000	1,634,000	3,228,000	3,846,000
Consolidated Funds
Interest and dividends	2,374,000	2,294,000	8,148,000	8,565,000
Other revenues	57,000	9,000	91,000	14,000
Total revenues	252,047,000	221,028,000	768,308,000	706,985,000
Interest and dividends expense	56,477,000	26,000,000	125,089,000	74,846,000
Total net revenues	195,570,000	195,028,000	643,219,000	632,139,000
Expenses
Employee compensation and benefits	120,320,000	128,483,000	388,611,000	397,543,000
Brokerage and trade execution costs	25,808,000	23,217,000	78,578,000	82,317,000
Underwriting expenses	2,846,000	4,412,000	12,383,000	13,260,000
Professional, advisory and other fees	15,535,000	7,698,000	39,396,000	20,541,000
Service fees	5,943,000	4,880,000	17,266,000	14,927,000
Communications	8,295,000	7,894,000	24,654,000	22,566,000
Occupancy and equipment	9,784,000	10,140,000	30,160,000	30,385,000
Depreciation and amortization	5,082,000	3,139,000	14,990,000	9,558,000
Client services and business development	10,364,000	6,671,000	33,549,000	22,767,000
Goodwill Impairment	0	0	4,100,000	0
Reinsurance claims, commissions and amortization of deferred acquisition costs	8,195,000	8,773,000	25,139,000	27,428,000
Other expenses	5,276,000	5,335,000	14,929,000	15,007,000
Consolidated Funds
Interest and dividends	1,153,000	1,270,000	3,376,000	5,660,000
Professional, advisory and other fees	857,000	191,000	1,375,000	748,000
Brokerage and trade execution costs	15,000	39,000	103,000	192,000
Other expenses	491,000	187,000	1,375,000	667,000
Total expenses	219,964,000	212,329,000	689,984,000	663,566,000
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	18,446,000	32,040,000	61,440,000	64,728,000
Gain (loss) on debt extinguishment	0	0	0	(556,000)
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	13,613,000	8,280,000	22,793,000	52,284,000
Net realized and unrealized gains (losses) on derivatives	293,000	1,664,000	(1,188,000)	6,258,000
Net gains (losses) on foreign currency transactions	(10,000)	(2,000)	(69,000)	250,000
Total other income (loss)	32,342,000	41,982,000	82,976,000	122,964,000
Income (loss) before income taxes	7,948,000	24,681,000	36,211,000	91,537,000
Income tax expense (benefit)	1,365,000	5,083,000	9,615,000	15,999,000
Net income (loss)	6,583,000	19,598,000	26,596,000	75,538,000
Net Income (Loss) Attributable to Noncontrolling Interest	2,770,000	4,110,000	7,188,000	37,798,000
Net income (loss) attributable to Cowen Inc.	3,813,000	15,488,000	19,408,000	37,740,000
Preferred stock dividends	1,698,000	1,698,000	5,094,000	5,094,000
Net income (loss) attributable to Cowen Inc. common stockholders	$ 2,115,000	$ 13,790,000	$ 14,314,000	$ 32,646,000
Weighted average common shares outstanding:
Basic (in shares)	29,529	29,610	29,687	29,662
Diluted (in shares)	31,264	30,844	31,381	30,613
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ 0.07	$ 0.47	$ 0.48	$ 1.10
Earnings Per Share, Diluted (in dollars per share)	$ 0.07	$ 0.45	$ 0.46	$ 1.07