Significant Accounting Policies (Details) (USD $)				12 Months Ended
	Dec. 31, 2013 cowenfund	Dec. 31, 2012	Dec. 31, 2013 Investment Company cowenfund	Dec. 31, 2013 Maximum	Dec. 31, 2013 Minimum	Dec. 31, 2013 Telephone and computer equipment Maximum	Dec. 31, 2013 Telephone and computer equipment Minimum	Dec. 31, 2013 Computer software Maximum	Dec. 31, 2013 Computer software Minimum	Dec. 31, 2013 Furniture and fixtures Maximum	Dec. 31, 2013 Furniture and fixtures Minimum	Dec. 31, 2013 Leasehold improvements Maximum	Dec. 31, 2013 Leasehold improvements Minimum	Dec. 31, 2013 Capitalized lease assets
Organization [Line Items]
Redeemable Noncontrolling Interest, Redemption Fee, Percent				5.00%	1.00%
Property, Plant and Equipment, Useful Life						5 years	3 years	5 years	3 years	8 years	3 years	10 years	1 year	5 years
Number of funds, Consolidated	8		3
Deferred rent	$ 14,554,000	$ 13,822,000
Total net assets of consolidated VIEs	$ 8,200,000