Regulatory Requirements Regulatory (Tables)

9 Months Ended

Sep. 30, 2018

Regulatory [Abstract]

Computation of Net Capital under Securities and Exchange Commission Regulation

Subsidiary	Net Capital		Minimum Net Capital Requirement		Excess Net Capital
	(dollars in millions)
Cowen and Company		$161.5		$1.0		$160.5
Cowen Execution		$114.2		$2.4		$111.8
ATM Execution		$1.7		$0.3		$1.4
Cowen Prime		$16.6		$0.3		$16.3
Westminster		$16.6		$0.3		$16.3
Cowen International Ltd		$13.2		$9.1		$4.1
Cowen Execution Ltd		$5.0		$3.2		$1.8