Acquisitions	3 Months Ended
Mar. 31, 2013
Business Combinations [Abstract]
Acquisitions	Acquisitions On March 11, 2013, the Company completed its acquisition of Dahlman Rose & Company, LLC, 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 is not expected to be significant. Dahlman Rose & Company, LLC was subsequently renamed to Cowen Securities LLC ("Cowen Securities"). Post acquisition, Cowen Securities is included in the broker-dealer segment. The Company is in discussions with the sellers regarding certain items, resolution of which will potentially impact the purchase price, assets and liabilities recognized and the resulting goodwill. The Company does not believe the impact will be material. The preliminary purchase price allocation of Cowen Securities is based upon all information available to us at the present time, and is based upon management's preliminary estimates of the fair values using valuation techniques including income, cost and market approaches. The purchase price allocation is preliminary pending the Company's final determination of the fair values of the assets and liabilities, which the Company expects will occur within twelve months following the acquisition. Upon the completion of the final purchase price allocation, any reallocation of fair values to the assets acquired and liabilities assumed in the acquisitions could have an impact on the amounts recognized on the condensed consolidated statements of operations. 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. Accordingly, the Company recognized goodwill in the amount of $7.7 million (See Note 8) which is deductible for tax purposes. The Company recognized approximately $1.2 million of acquisition-related costs, including legal, accounting, and valuation services for the three months ended March 31, 2013. These costs are included in professional, advisory and other fees and other expenses in the condensed consolidated statements of operations.

Acquisitions

3 Months Ended

Mar. 31, 2013

On March 11, 2013, the Company completed its acquisition of Dahlman Rose & Company, LLC, 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 is not expected to be significant. Dahlman Rose & Company, LLC was subsequently renamed to Cowen Securities LLC ("Cowen Securities"). Post acquisition, Cowen Securities is included in the broker-dealer segment.

The Company is in discussions with the sellers regarding certain items, resolution of which will potentially impact the purchase price, assets and liabilities recognized and the resulting goodwill. The Company does not believe the impact will be material. The preliminary purchase price allocation of Cowen Securities is based upon all information available to us at the present time, and is based upon management's preliminary estimates of the fair values using valuation techniques including income, cost and market approaches. The purchase price allocation is preliminary pending the Company's final determination of the fair values of the assets and liabilities, which the Company expects will occur within twelve months following the acquisition. Upon the completion of the final purchase price allocation, any reallocation of fair values to the assets acquired and liabilities assumed in the acquisitions could have an impact on the amounts recognized on the condensed consolidated statements of operations.

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. Accordingly, the Company recognized goodwill in the amount of $7.7 million (See Note 8) which is deductible for tax purposes.

The Company recognized approximately $1.2 million of acquisition-related costs, including legal, accounting, and valuation services for the three months ended March 31, 2013. These costs are included in professional, advisory and other fees and other expenses in the condensed consolidated statements of operations.