Organization and Business	3 Months Ended
Organization and Business	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business	Organization and Business Cowen Inc., a Delaware corporation formed in 2009, is a diversified financial services firm that, together with its consolidated subsidiaries (collectively, "Cowen" or the "Company"), provides investment banking, research, sales and trading, prime brokerage, global clearing, commission management services and investment management through its two business segments: the Operating Company ("Op Co") and the Asset Company ("Asset Co"). The Op Co segment consists of four divisions: the Investment Banking division, the Markets division, the Research division and the Cowen Investment Management ("CIM") division. The Company refers to the Investment Banking division, the Markets division and the Research division combined as its investment banking businesses. Op Co's investment banking businesses offer advisory and global capital markets origination, domain knowledge-driven research, sales and trading platforms for institutional investors, global clearing, commission management services and also a comprehensive suite of prime brokerage service. Sectors covered by Op Co's investment banking business include healthcare, technology, media and telecommunications, consumer, industrials, information and technology services, and energy. Op Co’s CIM division includes advisers to investment funds (including private equity structures and privately placed hedge funds) and registered funds. The Asset Co segment consists of certain of the Company's private investments, private real estate investments and other legacy investment strategies. The focus of Asset Co is to drive future monetization of the invested capital of the segment. Change in Segments The Company continually monitors and reviews its segment reporting structure in accordance with authoritative guidance to determine whether any changes have occurred that would impact its reportable segments. Because of the change in the Chief Operating Decision Maker ("CODM") of the Company at the end of 2017, the Company experienced a strategic shift to refocus the Company's businesses on a set of differentiated products which are aligned to the content and insight within the Company's domain of expertise. During the second quarter of 2019, the Company realigned the business and reportable segment information that the CODM regularly reviews to evaluate performance for operating decision-making purposes, including evaluation and allocation of resources. As a result, the Company changed its segment reporting structure based on the Company's domain expertise as a driver of balance sheet harmonization and repeatable revenues for its operating business versus the Company's long-term monetization strategies. As a result of the change in segments during the second quarter of 2019, the Company has the following business segments: •The Op Co segment consists of four divisions: Investment Banking, Markets, Research and Cowen Investment Management. Each of Op Co's four divisions leverage the Research division’s core domain expertise to drive harmonized repeatable revenue for the segment. ◦The Investment Banking division includes public and private capital raising transactions and providing strategic advisory services. ◦The Markets division includes trading equity, equity-linked and fixed income securities on behalf of institutional investors as well as a full-service suite of prime brokerage services, cross-asset trading, securities finance, global execution, clearing and commission management businesses. ◦The Research division provides thought leadership and domain expertise. The research content that is created helps to facilitate brokerage revenue in the Markets division, provides research coverage for clients of the Investment Banking division and facilitate investor relationships and investing within CIM's innovative investment products and solutions. ◦The CIM division offers innovative investment products and solutions across the liquidity spectrum to institutional and private clients. CIM offers investors access to a number of strategies to meet their specific needs including merger arbitrage, activism, healthcare royalties, private healthcare investing and private sustainable investing many of which leverage the content and domain expertise that are aligned with the Company's core areas of expertise, which the Company refers to as Cowen DNA. •The Asset Co segment consists of certain of the Company's private investments, private real estate investments and other legacy investment strategies.