Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Property, Plant and Equipment Useful Life

Asset	Depreciable Lives	Depreciation and/or Amortization Method
Telephone and computer equipment	3-5 years	Straight-line
Computer software	3-8 years	Straight-line
Furniture and fixtures	5 years	Straight-line
Leasehold improvements	2-15 years	Straight-line
Capitalized lease asset	5 years	Straight-line
Aircraft and related equipment	10-20 years	Straight-line
Modifications to aircraft	4-10 years	Straight-line

Schedule of New Accounting Pronouncements and Changes in Accounting Principles

Condensed Consolidated Statements of Financial Condition	As of March 31, 2018
	As reported		ASC 606 Impact			Adjusted (a)
	(dollars in thousands)
Assets
Fees receivable, net of allowance	$	136,541	$	6,399		$	142,940
Other investments	157,293		(6,399		)	150,894
Stockholders' equity	$	758,787	$	1,412		$	760,199

Condensed Consolidated Statements of Operations	Three Months Ended March 31, 2018
	As reported		ASC 606 Impact			Adjusted (a)
	(dollars in thousands)
Revenues
Investment banking	$	97,988	$	(4,063	)	$	93,925
Incentive income	16		2,307			2,323
Total revenues	251,384		(1,756		)	249,628
Expenses
Underwriting expenses	4,063		(4,063		)	—
Total expenses	250,286		(4,063		)	246,223
Net gains (losses) on securities, derivatives and other investments	15,969		1,454			17,423
Net income (loss) attributable to Cowen Inc. common stockholders	$	15,155	$	853		$	16,008

Condensed Consolidated Statements of Cash Flows	Three Months Ended March 31, 2018
	As reported			ASC 606 Impact			Adjusted (a)
	(dollars in thousands)
Cash flows from operating activities:
Net income (loss)	$	28,009		$	858		$	28,867
Adjustments to reconcile net income (loss) to net cash provided by / (used in) operating activities:
Net (gains) losses on securities, derivatives, and other investments	(7,924		)	735			(7,189		)
(Increase) decrease in operating assets:
Fees receivable, net of allowance	(30,996		)	(781		)	(31,777		)
Net cash provided by / (used in) operating activities	(35,506		)	812			(34,694		)
Cash flows from investing activities:
Purchase of other investments	(11,475		)	(812		)	(12,287		)
Net cash provided by / (used in) investing activities	$	(5,395	)	$	(812	)	$	(6,207	)