Regulatory Requirements Regulatory (Tables)

12 Months Ended

Dec. 31, 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		$91.9		$1.0		$90.9
Cowen Execution		$112.7		$2.3		$110.4
ATM Execution		$3.1		$0.3		$2.8
Cowen Prime		$8.7		$0.3		$8.4
Westminster		$14.5		$0.3		$14.2
Cowen International Ltd		$12.9		$9.9		$3.0
Cowen Execution Ltd		$4.9		$3.2		$1.7