Acquisitions	9 Months Ended
Sep. 30, 2014
Business Combinations [Abstract]
Acquisitions	Acquisitions On March 11, 2013, the Company completed its acquisition of all of the outstanding interests in Dahlman Rose & Company, LLC ("Dahlman"), a privately-held investment bank specializing in the energy, metals and mining, transportation, chemicals and agriculture sectors. This acquisition was an all-stock transaction. In the aggregate, the purchase price, assets acquired and liabilities assumed were not significant and the near term impact to the Company and its consolidated results of operations and cash flows was not expected to be significant. Dahlman was subsequently renamed to Cowen Securities LLC ("Cowen Securities"). Following the acquisition, the Cowen Securities broker-dealer ceased operations and its business was fully integrated into Cowen and Company. The acquisition was accounted for under the acquisition method of accounting in accordance with accounting principles generally accepted in the United States of America ("US GAAP"). As such, results of operations for the Cowen Securities are included in the accompanying condensed consolidated statements of operations since the date of the acquisition, and the assets acquired, liabilities assumed and the resulting goodwill were recorded at their fair values within their respective line items on the accompanying condensed consolidated statement of financial condition. The goodwill is fully deductible for tax purposes.

Acquisitions

9 Months Ended

Sep. 30, 2014

On March 11, 2013, the Company completed its acquisition of all of the outstanding interests in Dahlman Rose & Company, LLC ("Dahlman"), a privately-held investment bank specializing in the energy, metals and mining, transportation, chemicals and agriculture sectors. This acquisition was an all-stock transaction. In the aggregate, the purchase price, assets acquired and liabilities assumed were not significant and the near term impact to the Company and its consolidated results of operations and cash flows was not expected to be significant. Dahlman was subsequently renamed to Cowen Securities LLC ("Cowen Securities"). Following the acquisition, the Cowen Securities broker-dealer ceased operations and its business was fully integrated into Cowen and Company.

The acquisition was accounted for under the acquisition method of accounting in accordance with accounting principles generally accepted in the United States of America ("US GAAP"). As such, results of operations for the Cowen Securities are included in the accompanying condensed consolidated statements of operations since the date of the acquisition, and the assets acquired, liabilities assumed and the resulting goodwill were recorded at their fair values within their respective line items on the accompanying condensed consolidated statement of financial condition. The goodwill is fully deductible for tax purposes.