Acquisitions	12 Months Ended
Dec. 31, 2014
Business Combinations [Abstract]
Acquisitions	Acquisitions and Divestitures Acquisition 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, LLC ("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 Cowen Securities are included in the accompanying 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 consolidated statement of financial condition. The goodwill is fully deductible for tax purposes. Divestitures During the fourth quarter of 2014, the Company made a decision to wind down the operations of the the securities lending business. The Company recorded impairment of goodwill in the amount of $2.3 million and impairment of unamortized intangibles of $0.9 million (See Note 9). The Company also wrote off the contingent liability due to the principals of the former entity of $2.1 million which is included in other revenues in the accompanying consolidated statements of operations. The Company also recognized certain expenses related to the termination of services. The Company considered the guidance for discontinued operations and determined that winding down the securities lending business does not represent a significant strategic shift in operations, therefore, the Company did not present it as discontinued operations. On September 29, 2014, the Company entered into an agreement with Neuberger Berman to sell its interest in Orchard Square Partners (“OSP”), which manages a global long/short credit investment strategy with approximately $420.8 million in client assets. The transaction closed on December 31, 2014 and therefore OSP was deconsolidated on that date. During the year ended December 31, 2014, the Company consolidated the results of operations. As of December 31, 2014, the total assets, liabilities and net assets attributable to the Company and non-controlling interest holders were not material. In accordance with the terms of the sale agreement all of the net assets of OSP as of December 31, 2014 were allocated to the Company and the non-controlling members of OSP in accordance with the respective ownership interests and will be distributed soon thereafter. The total sale price was $4.5 million which is included in other revenues in the accompanying consolidated statements of operations. In addition, in accordance with the terms of the agreement, Neuberger Berman is also required to pay the Company a portion of future net revenues of the credit business if certain revenue targets are achieved through 2018.

Acquisitions

12 Months Ended

Dec. 31, 2014

Acquisitions and Divestitures

Acquisition

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, LLC ("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 Cowen Securities are included in the accompanying 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 consolidated statement of financial condition. The goodwill is fully deductible for tax purposes.

Divestitures

During the fourth quarter of 2014, the Company made a decision to wind down the operations of the the securities lending business. The Company recorded impairment of goodwill in the amount of $2.3 million and impairment of unamortized intangibles of $0.9 million (See Note 9). The Company also wrote off the contingent liability due to the principals of the former entity of $2.1 million which is included in other revenues in the accompanying consolidated statements of operations. The Company also recognized certain expenses related to the termination of services. The Company considered the guidance for discontinued operations and determined that winding down the securities lending business does not represent a significant strategic shift in operations, therefore, the Company did not present it as discontinued operations.

On September 29, 2014, the Company entered into an agreement with Neuberger Berman to sell its interest in Orchard Square Partners (“OSP”), which manages a global long/short credit investment strategy with approximately $420.8 million in client assets. The transaction closed on December 31, 2014 and therefore OSP was deconsolidated on that date. During the year ended December 31, 2014, the Company consolidated the results of operations. As of December 31, 2014, the total assets, liabilities and net assets attributable to the Company and non-controlling interest holders were not material. In accordance with the terms of the sale agreement all of the net assets of OSP as of December 31, 2014 were allocated to the Company and the non-controlling members of OSP in accordance with the respective ownership interests and will be distributed soon thereafter. The total sale price was $4.5 million which is included in other revenues in the accompanying consolidated statements of operations. In addition, in accordance with the terms of the agreement, Neuberger Berman is also required to pay the Company a portion of future net revenues of the credit business if certain revenue targets are achieved through 2018.