Cowen (COWN) 10-Q 2 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	Cowen Group, Inc.
Entity Central Index Key	1,466,538
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		107,099,781

Condensed Consolidated Statemen

Condensed Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 92,854	$ 129,509
Cash collateral pledged	9,129	8,306
Securities owned, at fair value	864,685	792,206
Receivable on derivative contracts, at fair value	41,587	49,877
Securities borrowed	0	676,100
Other investments	153,334	167,464
Receivable from brokers	115,279	84,679
Fees receivable, net of allowance	54,107	46,498
Due from related parties	26,209	26,315
Fixed assets, net of accumulated depreciation and amortization of $30,649 and $25,968, respectively	27,159	26,388
Goodwill	44,261	34,906
Intangible assets, net of accumulated amortization of $27,154 and $25,581, respectively	15,410	8,483
Deferred tax assets, net	127,736	129,400
Other assets	37,038	34,230
Consolidated Funds
Cash and cash equivalents	16,625	501
Securities owned, at fair value	19,000	0
Other investments	255,896	189,377
Other assets	657	1,437
Total Assets	1,900,966	2,405,676
Liabilities
Securities sold, not yet purchased, at fair value	250,739	207,875
Payable for derivative contracts, at fair value	26,078	41,330
Securities loaned	0	682,493
Payable to brokers	328,902	335,822
Compensation payable	101,780	134,289
Notes payable and other debt	66,628	67,144
Convertible debt	123,149	118,475
Fees payable	19,296	6,331
Due to related parties	320	474
Accounts payable, accrued expenses and other liabilities	43,683	46,606
Consolidated Funds
Due to related parties	1,000	0
Contributions received in advance	5,000	0
Capital withdrawals payable	84	864
Accounts payable, accrued expenses and other liabilities	289	222
Total Liabilities	$ 966,948	$ 1,641,925
Commitments and Contingencies
Redeemable non-controlling interests	$ 171,245	$ 86,076
Stockholders' equity
Additional paid-in capital	896,933	772,296
(Accumulated deficit) retained earnings	(5,317)	(16,027)
Accumulated other comprehensive income (loss)	13	17
Less: Class A common stock held in treasury, at cost, 32,776,819 and 23,507,656 shares as of September 30, 2015 and December 31, 2014, respectively.	(130,024)	(79,771)
Total Stockholders' Equity	762,773	677,675
Total Liabilities and Stockholders' Equity	1,900,966	2,405,676
Convertible Preferred Stock
Stockholders' equity
Preferred stock	1	0
Common Stock Class A
Stockholders' equity
Common stock	1,167	1,160
Less: Class A common stock held in treasury, at cost, 32,776,819 and 23,507,656 shares as of September 30, 2015 and December 31, 2014, respectively.	(130,024)	(79,771)
Common Stock Class B
Stockholders' equity
Common stock	$ 0	$ 0

Consolidated Statements of Fina

Consolidated Statements of Financial Condition (Parenthetical) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Assets
Fixed assets, accumulated depreciation and amortization (in dollars)	$ 30,649,000	$ 25,968,000
Intangible assets, accumulated amortization (in dollars)	$ 27,154,000	$ 25,581,000
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	120,750	0
Preferred stock, shares outstanding	120,750	0
Preferred Stock, Liquidation Preference, Value	$ 120,750,000
Treasury Stock, Shares	32,776,819	23,507,656
Common Stock Class A
Stockholders' equity
Treasury Stock, Shares	32,776,819	23,507,656
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	139,874,887	135,198,855
Common stock, shares outstanding	107,098,068	111,691,199
Common stock, restricted shares	497,570	424,479
Common Stock Class B
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues
Investment banking	$ 53,012	$ 45,799	$ 186,763	$ 125,653
Brokerage	41,085	34,334	111,496	100,475
Management fees	10,519	9,796	31,169	28,412
Incentive income	93	(837)	365	4,385
Interest and dividends	3,604	13,725	9,846	35,437
Reimbursement from affiliates	3,355	2,473	10,499	7,391
Other revenue	1,312	1,120	2,684	2,427
Consolidated Funds
Interest and dividends	245	642	685	1,783
Other revenues	29	49	449	717
Total revenues	113,254	107,101	353,956	306,680
Expenses
Employee compensation and benefits	56,401	65,806	227,593	197,771
Floor brokerage and trade execution	6,415	5,125	18,418	16,638
Interest and dividends	7,367	12,429	19,241	29,694
Professional, advisory and other fees	6,392	4,621	16,874	12,596
Service fees	1,778	1,933	5,338	6,161
Communications	3,478	3,286	10,313	9,554
Occupancy and equipment	7,286	6,650	21,024	19,371
Depreciation and amortization	2,301	2,274	6,584	7,036
Client services and business development	5,132	6,577	18,316	16,726
Other expenses	3,783	3,364	11,442	9,750
Consolidated Funds
Interest and dividends	366	218	858	517
Professional, advisory and other fees	174	348	476	622
Floor brokerage and trade execution	(20)	1	46	7
Other expenses	114	68	246	189
Total expenses	100,967	112,700	356,769	326,632
Other income (loss)
Net gains (losses) on securities, derivatives and other investments	(23,612)	13,836	24,449	48,227
Consolidated Funds
Net realized and unrealized gains (losses) on investments and other transactions	333	532	8,073	8,474
Net realized and unrealized gains (losses) on derivatives	(78)	1,899	(404)	1,688
Net gains (losses) on foreign currency transactions	(13)	2	(45)	(17)
Total other income (loss)	(23,370)	16,269	32,073	58,372
Income (loss) before income taxes	(11,083)	10,670	29,260	38,420
Income tax expense (benefit)	(5,081)	141	5,212	266
Net income (loss)	(6,002)	10,529	24,048	38,154
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,344	4,006	10,980	13,409
Net income (loss) attributable to Cowen Group, Inc.	(10,346)	6,523	13,068	24,745
Preferred Stock Dividends	1,603	0	2,358	0
Net income (loss) attributable to Cowen Group, Inc. common stockholders	$ (11,949)	$ 6,523	$ 10,710	$ 24,745
Weighted average common shares outstanding:
Basic (in shares)	109,191	114,969	111,050	115,407
Diluted (in shares)	109,191	118,801	117,249	120,027
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ (0.11)	$ 0.06	$ 0.10	$ 0.21
Earnings Per Share, Diluted (in dollars per share)	$ (0.11)	$ 0.05	$ 0.09	$ 0.21

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 24,048	$ 38,154
Other comprehensive income (loss), net of tax:
Foreign currency translation	[1]	(4)	(233)
Defined benefit pension plan:
Net gain/(loss) arising during the period		0	(87)
Amortization of prior service cost included in net periodic pension cost		0	0
Total defined benefit pension plan	[1]	0	(87)
Total other comprehensive income, net of tax		(4)	(320)
Comprehensive income (loss)		$ 24,044	$ 37,834
[1]	During the periods presented, the Company did not have material reclassifications out of other comprehensive income.

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands		Total		Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings/(Accumulated deficit)	Call OptionAdditional Paid-in Capital	Cumulative Preferred Stock	Cumulative Preferred StockRetained Earnings/(Accumulated deficit)	Common Stock Class A
Balance at Dec. 31, 2013		$ 507,766		$ (48,084)	$ 737,341	$ 592	$ (183,243)		$ 0		$ 1,160
Common Stock, Shares, Outstanding at Dec. 31, 2013											115,026,633
Preferred stock, shares outstanding at Dec. 31, 2013									0
Redeemable Noncontrolling Interest at Dec. 31, 2013		85,814
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to Cowen Group, Inc.		24,745					24,745
Net income (loss) attributable to redeemable non-controlling interests		13,409
Defined benefit plans		(87)	[1]			(87)
Foreign currency translation		(233)	[1]			(233)
Capital contributions		10,273
Capital withdrawals		(18,067)
Restricted stock awards issued, shares											4,242,989
Purchase of treasury stock, at cost, shares											(5,634,819)
Purchase of treasury stock, at cost		(22,937)
Preferred stock dividends		0
Common stock issuance upon acquisition		0
Warrants issued		15,218
Stock options exercised, shares											0
Stock Options Exercised		116			116
Amortization of share based compensation		14,286			14,286
Balance at Sep. 30, 2014		538,874		(71,021)	766,961	272	(158,498)		$ 0		$ 1,160
Common Stock, Shares, Outstanding at Sep. 30, 2014											113,634,803
Preferred stock, shares outstanding at Sep. 30, 2014									0
Redeemable Noncontrolling Interest at Sep. 30, 2014		91,429
Balance at Dec. 31, 2014		$ 677,675		(79,771)	772,296	17	(16,027)		$ 0		$ 1,160
Common Stock, Shares, Outstanding at Dec. 31, 2014											111,691,199
Preferred stock, shares outstanding at Dec. 31, 2014		0							0
Redeemable Noncontrolling Interest at Dec. 31, 2014		$ 86,076
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to Cowen Group, Inc.		13,068					13,068
Net income (loss) attributable to redeemable non-controlling interests		10,980
Defined benefit plans	[1]	0
Foreign currency translation		(4)	[1]			(4)
Capital contributions		88,740
Capital withdrawals		(14,551)
Restricted stock awards issued, shares											4,027,405
Purchase of treasury stock, at cost, shares											(9,269,163)
Purchase of treasury stock, at cost		(50,253)
Preferred stock issuance, net of issuance costs									120,750
Preferred stock issuance, net of issuance costs		117,195			117,194				$ 1
Preferred stock dividends		(2,358)								$ (2,358)
Common stock issuance upon acquisition, shares											548,625
Common stock issuance upon acquisition		3,008			3,002						$ 6
Capped call option transaction		(15,878)						$ (15,878)
Income tax effect from share based compensation		3,714			3,714
Stock options exercised, shares											100,002
Stock Options Exercised		395			394						$ 1
Amortization of share based compensation		16,211			16,211
Balance at Sep. 30, 2015		$ 762,773		$ (130,024)	$ 896,933	$ 13	$ (5,317)		$ 1		$ 1,167
Common Stock, Shares, Outstanding at Sep. 30, 2015											107,098,068
Preferred stock, shares outstanding at Sep. 30, 2015		120,750							120,750
Redeemable Noncontrolling Interest at Sep. 30, 2015		$ 171,245
[1]	During the periods presented, the Company did not have material reclassifications out of other comprehensive income.

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income (loss)	$ 24,048	$ 38,154
Adjustments to reconcile net income (loss) to net cash provided by / (used in) operating activities:
Depreciation and amortization	6,584	7,036
Amortization of debt discount	4,674	3,241
Tax benefits from share based payment arrangements	3,714	0
Share-based compensation	16,211	14,286
Deferred tax benefit	(2,050)	0
Deferred rent obligations	(2,113)	(1,629)
Net loss on disposal of fixed assets	54	311
Purchases of securities owned, at fair value	(4,650,626)	(3,362,237)
Proceeds from sales of securities owned, at fair value	4,556,647	3,013,982
Proceeds from sales of securities sold, not yet purchased, at fair value	2,003,879	1,371,216
Payments to cover securities sold, not yet purchased, at fair value	(1,940,343)	(1,268,348)
Net (gains) losses on securities, derivatives and other investments	(32,719)	(38,181)
Consolidated Funds
Purchases of securities owned, at fair value	(12,000)	0
Purchases of other investments	(78,491)	(19,568)
Proceeds from sales of other investments	18,722	21,367
Net realized and unrealized (gains) losses on investments and other transactions	(6,749)	(11,320)
(Increase) decrease in operating assets:
Cash collateral pledged	(823)	2,045
Securities owned, at fair value, held at broker dealer	20,696	4,300
Receivable on derivative contracts, at fair value	8,290	9,820
Securities borrowed	676,100	(1,393,783)
Receivable from brokers	(26,744)	(28,169)
Fees receivable, net of allowance	(6,952)	1,501
Due from related parties	106	(2,806)
Other assets	(919)	(5,702)
Consolidated Funds
Cash and cash equivalents	(16,124)	1,680
Other assets	780	4,933
Increase (decrease) in operating liabilities:
Securities sold, not yet purchased, at fair value, held at broker dealer	(7,134)	(19,839)
Payable for derivative contracts, at fair value	(15,252)	(12,016)
Securities loaned	(682,493)	1,406,105
Payable to brokers	(7,010)	171,377
Compensation payable	(41,628)	8,636
Fees payable	12,965	3,840
Due to related parties	(154)	31
Accounts payable, accrued expenses and other liabilities	(7,746)	6,521
Consolidated Funds
Contributions received in advance	5,000	0
Due to related parties	1,000	0
Accounts payable, accrued expenses and other liabilities	67	(455)
Net cash provided by / (used in) operating activities	(178,533)	(73,671)
Cash flows from investing activities:
Purchases of other investments	(10,259)	(80,153)
Purchase of business, net of cash acquired	(14,936)	0
Cash convertible note economic hedge transaction	0	(35,710)
Proceeds from sales of other investments	37,368	75,622
Tenant allowance	0	1,240
Purchase of fixed assets	(5,191)	(6,890)
Net cash provided by / (used in) investing activities	6,982	(45,891)
Cash flows from financing activities:
Securities sold under agreement to repurchase	0	(3,657)
Proceeds from issuance of convertible debt	0	149,500
Proceeds from issuance of preferred stock, net of issuance costs	117,194	0
Capped call option transaction	(15,879)	0
Deferred debt issuance cost	0	(3,720)
Proceeds from sale of warrant	0	15,218
Borrowings on notes and other debt	2,140	6,217
Repayments on notes and other debt	(2,655)	(2,913)
Tax benefits from share-based payment arrangements	3,714	0
Proceeds from stock options exercised	395	116
Purchase of treasury stock	(41,697)	(17,327)
Cash paid to acquire net assets (contingent liability payable)	(1,725)	(518)
Capital contributions by redeemable non-controlling interests in operating entities	5,644	705
Capital withdrawals to redeemable non-controlling interests in operating entities	(8,203)	(9,575)
Consolidated Funds
Capital contributions by redeemable non-controlling interests in Consolidated Funds	83,097	9,568
Capital withdrawals to redeemable non-controlling interests in Consolidated Funds	(7,129)	(12,606)
Net cash provided by / (used in) financing activities	134,896	131,008
Change in cash and cash equivalents	(36,655)	11,446
Cash and cash equivalents at beginning of period	129,509	54,720
Cash and cash equivalents at end of period	92,854	66,166
Supplemental information
Purchase of treasury stock, at cost, through net settlement	8,556	5,610
Preferred stock dividends declared	2,358	0
Cash conversion option	0	35,710
Net assets (liabilities) acquired upon acquisition (net of cash)	11,688	0
Common stock issuance upon close of acquisition	$ 3,008	$ 0

Organization and Business

Organization and Business	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business	Organization and Business Cowen Group, Inc., a Delaware corporation formed in 2009, is a diversified financial services firm and, together with its consolidated subsidiaries (collectively, “Cowen,” “Cowen Group” or the “Company”), provides alternative investment management, investment banking, research, sales and trading and prime brokerage services through its two business segments: alternative investment and broker-dealer. The Company's alternative investment segment, includes hedge funds, private equity structures, registered investment companies and listed vehicles . The Company's broker-dealer segment offers research, sales and trading and investment banking services to companies and institutional investor clients primarily in the healthcare, technology, media and telecommunications, information and technology services, consumer, aerospace and defense, industrials, real estate investment trusts ("REITs"), energy and transportation sectors. Cowen's broker-dealer segment also offers a comprehensive suite of prime brokerage services.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2015
Acquisition [Abstract]
Acquisition	Acquisition On September 1, 2015, the Company completed its acquisition of all of the outstanding interests in Concept Capital Markets, LLC ("Concept"), a registered broker-dealer (member Financials Industry Regulatory Authority "FINRA" and SIPC) offering prime brokerage services and outsourced trading. Following the acquisition, Concept was renamed Cowen Prime Services, LLC ("Cowen Prime"). The acquisition was completed for a combination of cash and unregistered shares of the Company's Class A common stock and contingent consideration. In accordance with the terms of the purchase agreement, the Company is also required to pay to the sellers a portion of future net profits of the business over the period through December 31, 2020. The Company estimated the contingent consideration using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amount recognized. The undiscounted amount can range from zero to $6.7 million . 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, the results of operations for Concept 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 (see Note 8 ). The Company recognized total identifiable assets of $25.2 million (including cash and cash equivalents of $1.6 million , fixed assets of $0.6 million , intangibles and goodwill of $17.8 million and receivables and other assets of $5.1 million respectively). The Company also recognized accrued expenses and other liabilities of $2.6 million . The Company is currently in the process of finalizing the valuation for certain acquired assets of Concept; therefore, the fair value measurements as of September 30, 2015 and goodwill are preliminary and subject to measurement period adjustments. The allocation of the purchase price to the net assets acquired will be finalized as necessary, up to one year after the acquisition closing date, as information becomes available. Goodwill, which primarily relates to expected synergies from combining operations, is fully deductible for tax purposes and has been assigned to the broker-dealer segment of the Company. The Company recognized approximately $0.6 million of acquisition-related costs, including legal, accounting, and valuation services. These costs are included in professional, advisory and other fees in the accompanying condensed consolidated statements of operations. Included in the accompanying condensed consolidated statements of operations for the period from September 1, 2015 through September 30, 2015 are revenues of $2.2 million and net income of $0.1 million related to the Concept results of operations. The following unaudited supplemental pro forma information presents condensed consolidated financial results for the nine month periods as if the acquisition was completed as of January 1, 2014. This supplemental pro forma information has been prepared for comparative purposes only and is not intended to be indicative of what the Company's results would have been had the acquisition been completed on January 1, 2014, nor does it purport to be indicative of any future results. For the nine months ended September, 30 2015 2014 (dollars in thousands, except per share data) (unaudited) Revenues $ 375,651 $ 328,677 Net income (loss) attributable to Cowen Group, Inc. common stockholders 12,952 24,840 Net income per common share: Basic $ 0.12 $ 0.21 Diluted $ 0.11 $ 0.21

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies a. Basis of Presentation These unaudited condensed consolidated financial statements and related notes have been prepared in accordance with US GAAP and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) related to interim financial statements. Results for interim periods should not be considered indicative of results for any other interim period or for the full year. These financial statements should be read in conjunction with the audited consolidated financial statements as of December 31, 2014 and 2013 and for the years ended December 31, 2014, 2013, and 2012, included in the Form 10-K of Cowen Group as filed with the SEC on February 26, 2015 and amended on March 30, 2015. The financial information contained herein is unaudited; however, management believes all adjustments have been made that are necessary for a fair presentation of the results for the interim periods. The year-end balance sheet data was derived from audited financial statements, but does not include all disclosures required by US GAAP. These condensed consolidated financial statements include the accounts of the Company, its operating and other subsidiaries, and entities in which the Company has a controlling financial interest or a substantive controlling general partner interest. All material intercompany transactions and balances have been eliminated in consolidation. Certain fund entities that are consolidated in these condensed consolidated financial statements, as further discussed below, are not subject to these consolidation provisions with respect to their own investments pursuant to their specialized accounting. The Company serves as the managing member/general partner and/or investment manager to affiliated fund entities which it sponsors and manages. Funds in which the Company has a controlling financial interest are consolidated with the Company pursuant to US GAAP as described below. Consequently, the Company's condensed consolidated financial statements reflect the assets, liabilities, income and expenses of these funds on a gross basis. The ownership interests in these funds that are not owned by the Company are reflected as redeemable non-controlling interests in consolidated subsidiaries in the accompanying condensed consolidated financial statements. The management fees and incentive income earned by the Company from these funds are eliminated in consolidation. b. Principles of consolidation The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting operating entity ("VOE") or a variable interest entity ("VIE") under US GAAP. Voting Operating Entities — VOEs are entities in which (i) the total equity investment at risk is sufficient to enable the entity to finance its activities independently and (ii) the equity holders at risk have the obligation to absorb losses, the right to receive residual returns and the right to direct the activities of the entity that most significantly impact the entity's economic performance. Under US GAAP, the usual condition for a controlling financial interest in a VOE is ownership of a majority voting interest. Accordingly, the Company consolidates VOEs in which it owns a majority of the entity's voting shares or units. US GAAP also provides that a general partner of a limited partnership (or a managing member, in the case of a limited liability company) is presumed to control the partnership, and thus should consolidate it, unless a simple majority of the limited partners has the right to remove the general partner without cause or to terminate the partnership. In accordance with these standards, the Company presently consolidates three entities deemed to be VOEs for which it acts as the general partner and investment manager. As of September 30, 2015 and December 31, 2014 and during the three and nine month periods ended September 30, 2015 and 2014 , the Company consolidated the following funds: Ramius Enterprise LP (“Enterprise LP”) and Ramius Merger Fund LLC (the "Merger Fund") and as of May 1, 2015, the date that the entity began operations, the Company also consolidates Quadratic Fund LLC ("Quadratic LLC") (collectively the "Consolidated Funds") . RCG Linkem II LLC, an investment company, is consolidated during the period ending September 30, 2015 . It was formed to make an investment in a wireless broadband communication provider in Italy. Cowen AV Investment LLC, an investment company, was consolidated up through the first quarter of 2015 when it was liquidated. It was formed to make an investment in a biotechnology company focused on developing gene therapies for certain medical needs. Ramius Co-Investment I LLC and Ramius Co-Investment II LLC, both investment companies, were formed to invest in biomedical companies that develop gene therapies for severe genetic disorders. Ramius Co-Investment I LLC was consolidated as of December 31, 2013 but was deconsolidated during the first quarter of 2014 when it was liquidated. Ramius Co-Investment II LLC was consolidated but was liquidated during the quarter ended September 30, 2014. The Company determined that all four investment companies are (or were) VOE's due to the Company's controlling equity interests held through the managing member and/or affiliates and control exercised by the managing member who is not subject to substantive removal rights. Variable Interest Entities— VIEs are entities that lack one or more of the characteristics of a VOE. In accordance with US GAAP, an enterprise must consolidate all VIEs of which it is the primary beneficiary. Under the US GAAP consolidation model for VIEs, an enterprise that (1) has the power to direct the activities of a VIE that most significantly impacts the VIE's economic performance, and (2) has an obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE, is considered to be the primary beneficiary of the VIE and thus is required to consolidate it. However, the Financial Accounting Standards Board ("FASB") has deferred the application of the revised consolidation model for VIEs that meet the following conditions (see "recently issued accounting pronouncements"): (a) the entity has all the attributes of an investment company as defined under AICPA Audit and Accounting Guide, Investment Companies, or does not have all the attributes of an investment company but is an entity for which it is acceptable based on industry practice to apply measurement principles that are consistent with investment companies, (b) the reporting entity does not have explicit or implicit obligations to fund any losses of the entity that could potentially be significant to the entity, and (c) the entity is not a securitization entity, asset-backed financing entity or an entity that was formerly considered a qualifying special-purpose entity. The Company's involvement with its funds is such that all three of the above conditions are met for substantially all of the funds managed by the Company. Where the VIEs have qualified for the deferral, the analysis is based on previous consolidation rules. These rules require an analysis to (a) determine whether an entity in which the Company holds a variable interest is a variable interest entity and (b) whether the Company's involvement, through holding interests directly or indirectly in the entity or contractually through other variable interests (e.g., management and performance related fees), would be expected to absorb a majority of the VIE's expected losses, receive a majority of the VIEs expected residual returns, or both. If these conditions are met, the Company is considered to be the primary beneficiary of the VIE and thus is required to consolidate it. The Company reconsiders whether it is the primary beneficiary of a VIE by performing a periodic qualitative and/or quantitative analysis of the VIE that includes a review of, among other things, its capital structure, contractual agreements between the Company and the VIE, the economic interests that create or absorb variability, related party relationships and the design of the VIE. As of September 30, 2015 and December 31, 2014 , the Company consolidated three and two VIEs, respectively. As of September 30, 2015 and December 31, 2014 , the total net assets of the consolidated VIEs were $1.0 million and $2.0 million , respectively. The VIEs act as managing members/general partners and/or investment managers to affiliated fund entities which they sponsor and/or manage. The VIEs are financed through their operations and/or loan agreements with the Company. As of September 30, 2015 and December 31, 2014 , the Company holds variable interests in Ramius Enterprise Master Fund Ltd (“Enterprise Master”), Ramius Merger Master Fund Ltd ("Merger Master"), as of May 1, 2015, Quadratic Master Fund LTD (Quadratic Master Fund") and, as of September 1, 2015, Cowen Private Investments LP (collectively the “Unconsolidated Master Funds”) through the Consolidated Funds. Investment companies, which account for their investments under the specialized industry accounting guidance for investment companies prescribed under US GAAP, are not subject to the consolidation provisions for their investments. Therefore, the Company has not consolidated the Unconsolidated Master Funds. In the ordinary course of business, the Company also sponsors various other entities that it has determined to be VIEs. These VIEs are primarily funds and real estate entities for which the Company serves as the general partner, managing member and/or investment manager with decision-making rights. The Company does not consolidate any of these funds or real estate entities that are VIEs as it has concluded that it is not the primary beneficiary in each instance. Fund investors are entitled to all of the economics of these VIEs with the exception of the management fee and incentive income, if any, earned by the Company. The Company's involvement with funds and real estate entities that are unconsolidated VIEs is limited to providing investment management services in exchange for management fees and incentive income. Although the Company may advance amounts and pay certain expenses on behalf of the funds and real estate entities that it considers to be VIEs, it does not provide, nor is it required to provide, any type of substantive financial support to these entities outside of regular investment management services (see Note 5 for additional disclosures on VIEs). Equity Method Investments — For operating entities over which the Company exercises significant influence but which do not meet the requirements for consolidation as outlined above, the Company uses the equity method of accounting. The Company's investments in equity method investees are recorded in other investments in the accompanying consolidated statements of financial condition. The Company's share of earnings or losses from equity method investees is included in net gains (losses) on securities, derivatives and other investments in the accompanying consolidated statements of operations. The Company evaluates for impairment its equity method investments whenever events or changes in circumstances indicate that the carrying amounts of such investments may not be recoverable. The difference between the carrying value of the equity method investment and its estimated fair value is recognized as an impairment charge when the loss in value is deemed other than temporary. Other — If the Company does not consolidate an entity, apply the equity method of accounting or account for an investment under the cost method, the Company accounts for such entities (primarily, all securities of such entity which are bought and held principally for the purpose of selling them in the near term as trading securities) in accordance with US GAAP, at fair value with unrealized gains (losses) resulting from changes in fair value reflected within net gains (losses) on securities, derivatives and other investments in the accompanying consolidated statements of operations. Retention of Specialized Accounting — The Consolidated Funds are investment companies and apply specialized industry accounting for investment companies. The Company has retained this specialized accounting for these funds pursuant to US GAAP. The Company reports its investments on the consolidated statements of financial condition at their estimated fair value, with unrealized gains (losses) resulting from changes in fair value reflected within net realized and unrealized gains (losses) on investments and other transactions. Accordingly, the accompanying condensed consolidated financial statements reflect different accounting policies for investments depending on whether or not they are held through a consolidated investment company. In addition, the Company's broker-dealer subsidiaries, Cowen and Company, ATM Execution LLC ("ATM Execution"), Cowen Prime, ATM USA, LLC ("ATM USA") (liquidated during the first quarter of 2015) and Cowen Equity Finance LP ("Cowen Equity Finance") (liquidated during the first quarter of 2015), apply the specialized industry accounting for brokers and dealers in securities also prescribed under US GAAP. The Company also retains specialized accounting in consolidation. c. Use of estimates The preparation of the accompanying condensed consolidated financial statements in conformity with US GAAP requires the management of the Company to make estimates and assumptions that affect the fair value of securities and other investments, the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the accompanying condensed consolidated financial statements, the accounting for goodwill and identifiable intangible assets and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates. d. Valuation of investments and derivative contracts US GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurements) and the lowest priority to unobservable inputs (level 3 measurements). The three levels of the fair value hierarchy are as follows: Level 1 Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date; Level 2 Inputs other than quoted prices that are observable for the asset or liability either directly or indirectly, including inputs in markets that are not considered to be active; and Level 3 Fair value is determined based on pricing inputs that are unobservable and includes situations where there is little, if any, market activity for the asset or liability. The determination of fair value for assets and liabilities in this category requires significant management judgment or estimation. Inputs are used in applying the various valuation techniques and broadly refer to the assumptions that market participants use to make valuation decisions, including assumptions about risk. Inputs may include price information, volatility statistics, specific and broad credit data, liquidity statistics, and other factors. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. However, the determination of what constitutes “observable” requires significant judgment by the Company. The Company considers observable data to be that market data which is readily available, regularly distributed or updated, reliable and verifiable, not proprietary, and provided by independent sources that are actively involved in the relevant market. The categorization of a financial instrument within the hierarchy is based upon the pricing transparency of the instrument and does not necessarily correspond to the Company's perceived risk of that instrument. The Company and its operating subsidiaries act as the manager for the Consolidated Funds. Both the Company and the Consolidated Funds hold certain investments which are valued by the Company, acting as the investment manager. The fair value of these investments is generally estimated based on proprietary models developed by the Company, which include discounted cash flow analysis, public market comparables, and other techniques and may be based, at least in part, on independently sourced market information. The material estimates and assumptions used in these models include the timing and expected amount of cash flows, the appropriateness of discount rates used, and, in some cases, the ability to execute, timing of, and estimated proceeds from expected financings. Significant judgment and estimation goes into the selection of an appropriate valuation methodology as well as the assumptions used in these models, and the timing and actual values realized with respect to investments could be materially different from values derived based on the use of those estimates. The valuation methodologies applied impact the reported value of the Company's investments and the investments held by the Consolidated Funds in the condensed consolidated financial statements. Certain of the Company's investments are relatively illiquid or thinly traded and may not be immediately liquidated on demand if needed. Fair values assigned to these investments may differ significantly from the fair values that would have been used had a ready market for the investments existed and such differences could be material . The Company primarily uses the “market approach” to value its financial instruments measured at fair value. In determining an instrument's level within the hierarchy, the Company categorizes the Company's financial instruments into three categories: securities, derivative contracts and other investments. To the extent applicable, each of these categories can further be divided between those held long or sold short. The Company has the option to measure certain financial assets and financial liabilities at fair value with changes in fair value recognized in earnings each period. The election is made on an instrument by instrument basis at initial recognition of an asset or liability or upon an event that gives rise to a new basis of accounting for that instrument. The Company has elected the fair value option for its investments through Cowen Investments, LLC and certain investments it holds though its operating companies. This option has been elected because the Company believes that it is consistent with the manner in which the business is managed as well as the way that financial instruments in other parts of the business are recorded. Securities — Securities with values based on quoted market prices in active markets for identical assets are classified within level 1 of the fair value hierarchy. These securities include active listed equities, certain U.S. government and sovereign obligations, ETF's, mutual funds and certain money market securities. The Company does not adjust the quoted price for such instruments, even in situations where the Company holds a large position and a sale could reasonably impact the quoted price. Certain positions for which trading activity may not be readily visible, consisting primarily of convertible debt, corporate debt and loans and restricted equities, are stated at fair value and classified within level 2 of the fair value hierarchy. The estimated fair values assigned by management are determined in good faith and are based on available information considering, trading activity, broker quotes, quotations provided by published pricing services, counterparties and other market participants, and pricing models using quoted inputs, and do not necessarily represent the amounts which might ultimately be realized. As level 2 investments include positions that are not always traded in active markets and/or are subject to transfer restrictions, valuations may be adjusted to reflect illiquidity and/or non-transferability. Derivative contracts — Derivative contracts can be exchange-traded or privately negotiated over-the-counter (“OTC”). Exchange-traded derivatives, such as futures contracts and exchange-traded option contracts, are typically classified within level 1 or level 2 of the fair value hierarchy depending on whether or not they are deemed to be actively traded. OTC derivatives, such as generic forwards, swaps and options, have inputs which can generally be corroborated by market data and are therefore classified within level 2. OTC derivatives, such as swaps and options where market data is not readily available or observable are classified as level 3. Other investments — Other investments consist primarily of portfolio funds, real estate investments and equity method investments, which are valued as follows : i. Portfolio funds— Portfolio funds (“Portfolio Funds”) include interests in funds and investment companies which may be managed by the Company or its affiliates. The Company follows US GAAP regarding fair value measurements and disclosures relating to investments in certain entities that calculate net asset value (“NAV”) per share (or its equivalent). The guidance permits, as a practical expedient, an entity holding investments in certain entities that either are investment companies as defined by the AICPA Audit and Accounting Guide, Investment Companies, or have attributes similar to an investment company, and calculate net asset value per share or its equivalent for which the fair value is not readily determinable, to measure the fair value of such investments on the basis of that NAV per share, or its equivalent, without adjustment. In accordance with US GAAP, investments which are valued using NAV per share as a practical expedient shall not be categorized within the fair value hierarchy. ii. Real estate investments— Real estate debt and equity investments are valued at fair value. The fair value of real estate investments are estimated based on the price that would be received to sell an asset in an orderly transaction between marketplace participants at the measurement date. Real estate investments without a public market are valued based on assumptions and valuation techniques used by the Company. Such valuation techniques may include discounted cash flow analysis, prevailing market capitalization rates or earnings multiples applied to earnings from the investment, analysis of recent comparable sales transactions, actual sale negotiations and bona fide purchase offers received from third parties, consideration of the amount that currently would be required to replace the asset, as adjusted for obsolescence, as well as independent external appraisals. In general, the Company considers several valuation techniques when measuring the fair value of a real estate investment. However, in certain circumstances, a single valuation technique may be appropriate. Real estate investments are reviewed on a quarterly basis by the Company for significant changes at the property level or a significant change in the overall market which would impact the value of the real estate investment resulting in unrealized appreciation or depreciation. Real estate and capital markets are cyclical in nature. Property and investment values are affected by, among other things, the availability of capital, occupancy rates, rental rates and interest and inflation rates. In addition, the Company invests in real estate and real estate related investments for which no liquid market exists. The market prices for such investments may be volatile and may not be readily ascertainable. Amounts ultimately realized by the Company from investments sold may differ from the fair values presented, and the differences could be material. The Company's real estate investments are typically categorized as a level 3 investment within the fair value hierarchy as management uses significant unobservable inputs in determining their estimated fair value. See Notes 5 and 6 for further information regarding the Company's investments, including equity method investments, and fair value measurements. e. Securities borrowed and securities loaned Securities borrowed and securities loaned are carried at the amounts of cash collateral advanced or received on a gross basis. The related rebates are recorded in the statement of operations as interest income and interest expense. Securities borrowed transactions require the Company to deposit cash collateral with the lender. With respect to securities loaned, the Company receives cash collateral from the borrower. The initial collateral advanced or received approximates or is greater than the market value of securities borrowed or loaned. The Company monitors the market value of securities borrowed and loaned on a daily basis, with additional collateral obtained or returned, as necessary. Securities borrowed and loaned may also result in credit exposures for the Company in an event that the counterparties are unable to fulfill their contractual obligations. The Company minimizes its credit risk by continuously monitoring its credit exposure and collateral values by demanding additional or returning excess collateral in accordance with the netting provisions available in the master securities lending contracts in place with the counterparties. Fees and interest received or paid are recorded in interest and dividend income and interest expense, respectively, on an accrual basis. In cases where the fair value basis of accounting is elected, any resulting change in fair value is reported in trading revenues. Accrued interest income and expense are recorded in the same manner as under the accrual method. During the fourth quarter of 2014, the Company made a decision to wind down the operations of its securities lending business. At December 31, 2014 , the Company did not have any securities lending transactions for which fair value basis of accounting was elected. f. Debt Long-term debt is carried at the principal amount borrowed net of any discount/premium. The discount is accreted to interest expense using the effective interest method over the remaining life of the underlying debt obligations. Accrued but unpaid coupon interest is included in accrued expenses and other liabilities in the accompanying consolidated statements of financial condition. g. Deferred rent Deferred rent primarily consists of step rent, allowances from landlords and valuing the Company's lease properties in accordance with US GAAP. Step rent represents the difference between actual operating lease payments due and straight-line rent expense, which is recorded by the Company over the term of the lease, including the build-out period. This amount is recorded as deferred rent in the early years of the lease, when cash payments are generally lower than straight-line rent expense, and reduced in the later years of the lease when payments begin to exceed the straight-line expense. Landlord allowances are generally comprised of amounts received and/or promised to the Company by landlords and may be received in the form of cash or free rent. These allowances are part of the negotiated terms of the lease. The Company records a receivable from the landlord and a deferred rent liability when the allowances are earned. This deferred rent is amortized into income (through lower rent expense) over the term (including the pre-opening build-out period) of the applicable lease, and the receivable is reduced as amounts are received from the landlord. Liabilities resulting from valuing the Company's leased properties acquired through business combinations are quantified by comparing the current fair value of the leased space to the current rental payments on the date of acquisition. Deferred rent, included in accounts payable, accrued expenses and other liabilities in the accompanying consolidated statements of financial condition, as of September 30, 2015 and December 31, 2014 is $12.2 million and $13.1 million , respectively. h. Recently issued accounting pronouncements In September 2015, as part of its simplification initiative, FASB issued a new accounting pronouncement which eliminates the concept of measurement period adjustments in a business combination transaction. The amendments require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendments also require that the acquirer record, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date and eliminate the current requirement to retrospectively account for those adjustments. For public business entities the guidance is effective prospectively for reporting periods beginning after December 15, 2015. The Company is currently evaluating the impact of this guidance on the Company’s financial condition, results of operations and cash flows. In May 2015, the FASB amended the guidance for fair value measurement and issued the amendment which removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share as practical expedient. The amendment also removes the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the net asset value per share as practical expedient. For public companies, the guidance is effective retrospectively for the reporting periods beginning after December 15, 2015 and early adoption is permitted. During the quarter ended June 30, 2015, the Company early adopted the guidance and excluded the investments measured at fair value using the net asset value per share as practical expedient from the fair value hierarchy. The adoption did not result in any impact on the Company’s financial condition, result of operations and cash flows. See Note 6 which reflects the impact of adopting this guidance and further information. In April 2015, the FASB issued a new accounting pronouncement simplifying the presentation of debt issuance costs. The accounting guidance requires that debt issuance costs related to a recognized debt liability be reported on the Consolidated Statements of Financial Condition as a direct deduction from the carrying amount of that debt liability. The guidance is effective retrospectively for reporting periods beginning after December 15, 2015 and early adoption is permitted. In August 2015, FASB issued another pronouncement amending the SEC guidance pursuant to this amendment. The adoption of this accounting guidance is not expected to have a material impact on the Company’s financial condition. In May 2014, the FASB issued guidance which amends and supersedes the revenue recognition requirements and most industry-specific guidance and creates a single source of revenue guidance. The new guidance outlines the principles an entity must apply to measure and recognize revenue and related cash flows. The guidance also provides a model for the measurement and recognition of gains and losses on the sale of certain non-financial assets. The guidance is effective for reporting periods beginning after December 15, 2017. In July 2015, the FASB confirmed a deferral of the effective date by one year, with early adoption on the original effective date permitted. The Company is currently evaluating the impact of this guidance on the Company’s financial condition, results of operations and cash flows. In February 2015, the FASB issued an accounting pronouncement which amends and updates its previous guidance regarding consolidation analysis. The amendment eliminates the deferral of certain consolidation standards for entities considered to be investment companies and modifies the consolidation analysis performed on certain types of legal entities. The guidance is effective for reporting periods beginning after December 15, 2015. The Company is currently evaluating the impact of the new guidance on our consolidated financial statements. In January 2015, the FASB issued a new accounting pronouncement regarding extraordinary items. The guidance eliminates the concept and presentation requiremen

Cash Collateral Pledged

Cash Collateral Pledged	9 Months Ended
	Sep. 30, 2015
Cash and Cash Equivalents [Abstract]
Cash Collateral Pledged	Cash Collateral Pledged As of September 30, 2015 and December 31, 2014 , the Company pledged cash collateral in the amount of $9.1 million and $8.3 million , respectively, which relates to letters of credit issued to the landlords of the Company's premises in New York City, Boston and San Francisco (See Note 14 ).

Investments of Operating Entiti

Investments of Operating Entities and Consolidated Funds	9 Months Ended
	Sep. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Investments of Operating Entities and Consolidated Funds	Investments of Operating Entities and Consolidated Funds a. Operating Entities Securities owned, at fair value Securities owned, at fair value are held by the Company and are considered held for trading. Substantially all equity securities are pledged to the clearing broker under terms which permit the clearing broker to sell or re-pledge the securities to others subject to certain limitations. As of September 30, 2015 and December 31, 2014 , securities owned, at fair value consisted of the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) U.S. Government securities (a) $ 3,015 $ 2,010 Preferred stock 15,771 15,070 Common stocks 712,489 597,476 Convertible bonds (b) 1,129 900 Corporate bonds (c) 113,585 159,557 Warrants and rights 3,871 1,417 Mutual funds 14,825 15,776 $ 864,685 $ 792,206 (a) As of September 30, 2015 , maturities ranged from December 2015 to August 2016 with interest rates ranged between 0% to 5.95% . As of December 31, 2014 , maturities ranged from May 2015 to April 2016 with interest rates ranged between 0% to 5.95% . (b) As of September 30, 2015 , maturities ranged from July 2016 to March 2018 with interest rates ranged between 8% to 10.00% . As of December 31, 2014 , the maturity was February 2015 with an interest rate of 10.00% . (c) As of September 30, 2015 , maturities ranged from March 2016 to February 2046 and interest rates ranged between 3.17% to 21.74% . As of December 31, 2014 , maturities ranged from February 2015 to February 2046 and interest rates ranged between 5.63% to 11.54% . Receivable on and Payable for derivative contracts, at fair value The Company's direct involvement with derivative financial instruments includes futures, currency forwards, equity swaps, and options. The Company's derivatives trading activities exposes the Company to certain risks, such as price and interest rate fluctuations, volatility risk, credit risk, counterparty risk, foreign currency movements and changes in the liquidity of markets. Upon issuance of the Company's cash convertible unsecured senior notes ("Convertible Notes") (See Note 14 ), the Company recognized the embedded cash conversion option at fair value of $35.7 million which is valued as of September 30, 2015 at $21.6 million and is included in payable for derivative contracts in the accompanying consolidated statement of financial condition. Also, on the date of issuance of the Convertible Notes, the Company entered into a separate cash convertible note economic hedge transaction (the "Hedge Transaction") with a counterparty (the “Option Counterparty”) whereby, the Company purchased a cash settled option contract with terms identical to the conversion option embedded in the Convertible Notes and simultaneously sold an equity settled warrant with a higher strike price. The Hedge Transaction is expected to reduce the Company’s exposure to potential cash payments in excess of the principal amount of converted notes that the Company may be required to make upon conversion of the Convertible Notes. The Company paid a premium of $35.7 million for the option under the Hedge Transaction and received a premium of $15.2 million for the equity settled warrant transaction, for a net cost of $20.5 million . The Hedge Transaction is valued at $21.6 million as of September 30, 2015 and is included in receivable on derivative contracts in the accompanying consolidated statement of financial condition. Aside from the initial premium paid, the Company will not be required to make any cash payments under the Hedge Transaction and could be entitled to receive an amount of cash from the Option Counterparty generally equal to the amount by which the market price per share of common stock exceeds the strike price of the Hedge Transaction during the relevant valuation period. The warrants cover 28,048,786 shares of the Company's Class A common stock and have an initial exercise price of $7.18 per share. The warrants expire over a period of 80 trading days beginning on November 14, 2018. The warrant transaction could have a dilutive effect to the extent that the market value per share of the Company’s Class A common stock exceeds the applicable strike price of the warrants. The Company's long and short exposure to derivatives is as follows: Receivable on derivative contracts As of September 30, 2015 As of December 31, 2014 Number of contracts / Notional Value Fair value Number of contracts / Notional Value Fair value (dollars in thousands) Futures $ 4,679 $ 68 $ 3,041 $ 75 Currency forwards $ 34,036 105 $ 23,961 310 Equity swaps $ 52,000 470 $ 12,904 251 Options other (a) 306,659 34,498 367,441 48,201 Foreign currency options $ 292,475 6,446 $ 32,200 1,040 $ 41,587 $ 49,877 (a) Includes index, equity, commodity future and cash conversion options. Payable for derivative contracts As of September 30, 2015 As of December 31, 2014 Number of contracts / Notional Value Fair value Number of contracts / Notional Value Fair value (dollars in thousands) Futures $ 32,423 $ 381 $ 2,213 $ 33 Currency forwards $ 43,788 107 $ — — Equity and credit default swaps $ 45,193 2,615 $ 18,352 1,603 Options other (a) 14,035 22,975 22,043 39,694 $ 26,078 $ 41,330 (a) Includes index, equity, commodity future and cash conversion options. The following tables present the gross and net derivative positions and the related offsetting amount, as of September 30, 2015 and December 31, 2014 . Gross amounts not offset in the Statement of Financial Condition Gross amounts recognized Gross amounts offset on the Consolidated Statements of Financial Condition (a) Net amounts included on the Consolidated Statements of Financial Condition Financial instruments Cash Collateral pledged (b) Net amounts (dollars in thousands) As of September 30, 2015 Receivable on derivative contracts, at fair value $ 41,587 $ — $ 41,587 $ — $ 8,950 $ 32,637 Payable for derivative contracts, at fair value 26,078 — 26,078 — 2,643 23,435 As of December 31, 2014 Receivable on derivative contracts, at fair value 49,877 — 49,877 — 2,588 47,289 Payable for derivative contracts, at fair value 41,330 — 41,330 — 1,603 39,727 (a) Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred. (b) Includes the amount of collateral held or posted. The realized and unrealized gains/(losses) related to derivatives trading activities were $(0.2) million and $5.1 million for the three months ended September 30, 2015 and 2014 and $(5.6) million and $1.4 million for the nine months ended September 30, 2015 and 2014 , respectively, and are included in other income in the accompanying consolidated statements of operations. Pursuant to the various derivatives transactions discussed above, except for the cash convertible note hedge (see Note 14 ) and exchange traded derivatives, the Company is required to post/receive collateral. As of September 30, 2015 and December 31, 2014 , collateral consisting of $20.9 million and $5.5 million of cash, respectively, is included in receivable from brokers and payable to brokers on the accompanying consolidated statements of financial condition. As of September 30, 2015 and December 31, 2014 all derivative contracts were with multiple major financial institutions. Other investments As of September 30, 2015 and December 31, 2014 , other investments included the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) (1) Portfolio Funds, at fair value $ 108,509 $ 103,466 (2) Real estate investments, at fair value 1,916 2,175 (3) Equity method investments 42,574 61,443 (4) Lehman claims, at fair value 335 380 $ 153,334 $ 167,464 (1) Portfolio Funds, at fair value The Portfolio Funds, at fair value as of September 30, 2015 and December 31, 2014 , included the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) HealthCare Royalty Partners (a)(*) $ 12,016 $ 11,935 HealthCare Royalty Partners II (a)(*) 7,439 6,648 Orchard Square Partners Credit Fund LP (b) 4,473 11,532 Starboard Value and Opportunity Fund LP (c)(*) 20,914 21,792 Starboard Partners Fund LP (d)(*) 13,785 14,652 Starboard Leaders Fund LP (e)(*) 1,251 1,367 Formation8 Partners Fund I, L.P. (f) 17,364 11,283 Formation8 Partners Hardware Fund I, L.P. (g) 1,125 — RCG LV Park Lane LLC (h) (*) 1,364 642 RCGL 12E13th LLC (i) (*) 632 638 RCG Longview Debt Fund V, L.P. (i) (*) 14,745 12,876 RCG LPP SME Co-Invest, L.P. (j) (*) 2,469 — Other private investment (k) 6,591 7,324 Other affiliated funds (l)(*) 4,341 2,777 $ 108,509 $ 103,466 * These portfolio funds are affiliates of the Company. The Company has no unfunded commitments regarding the portfolio funds held by the Company except as noted in Note 13 . (a) HealthCare Royalty Partners, L.P. and HealthCare Royalty Partners II, L.P. are private equity funds and therefore distributions will be made when cash flows are received from the underlying investments, typically on a quarterly basis. (b) Orchard Square Partners Credit Fund LP has a quarterly redemption policy with a 60 day notice period and a 4% penalty on redemptions of investments of less than a year in duration. (c) Starboard Value and Opportunity Fund LP permits quarterly withdrawals upon 90 days notice. (d) Starboard Partners Fund LP permits redemptions on a semi-annual basis on 180 days prior written notice subsequent to an initial two year lock up. (e) Starboard Leaders Fund LP does not permit withdrawals, but instead allows terminations with respect to capital commitments upon 30 days prior written notice at any time following the first anniversary of an investors initial capital contribution. (f) Formation8 Partners Fund I, L.P. is a private equity fund which invests in early stage and growth transformational information and energy technology companies. Distributions will be made when the underlying investments are liquidated. (g) Formation8 Partners Hardware Fund I, L.P. is a private equity fund which invests in early stage and growth hardware companies. Distributions will be made when the underlying investments are liquidated. (h) RCG LV Park Lane LLC is a single purpose entity formed to participate in a joint venture which acquired, at a discount, the mortgage notes on a portfolio of multifamily real estate properties located in Birmingham, Alabama. RCG LV Park Lane LLC is a private equity structure and therefore distributions will be made when the underlying investments are liquidated. (i) RCGL 12E13th LLC and RCG Longview Debt Fund V, L.P. are real estate private equity structures and therefore distributions will be made when the underlying investments are liquidated. (j) RCG LPP SME Co-Invest, L.P. is a single purpose entity formed to participate in a joint venture which acquired two fully entitled residential development sites in the New York City metro area. RCG LPP SME Co-Invest, L.P. is a private equity structure and therefore distributions will be made when the underlying investments are liquidated. (k) Other private investment represents the Company's closed end investment in a portfolio fund that invests in a wireless broadband communication provider in Italy. (l) The majority of these funds are affiliates of the Company or are managed by the Company and the investors can redeem from these funds as investments are liquidated. (2) Real estate investments, at fair value Real estate investments as of September 30, 2015 and December 31, 2014 are carried at fair value and include real estate equity investments held by RCG RE Manager, LLC (“RE Manager”), a real estate operating subsidiary of the Company, of $1.9 million and $2.2 million , respectively. (3) Equity method investments Equity method investments include investments held by the Company in several operating companies whose operations primarily include the day to day management of a number of real estate funds, including the portfolio management and administrative services related to the acquisition, disposition, and active monitoring of the real estate funds' underlying debt and equity investments. The Company's ownership interests in these equity method investments range from 20% to 55% . The Company holds a majority of the outstanding ownership interest (i.e., more than 50%) in RCG Longview Partners II, LLC. The operating agreement that governs the management of day-to-day operations and affairs of this entity stipulates that certain decisions require support and approval from other members in addition to the support and approval of the Company. As a result, all operating decisions made in this entity requires the support of both the Company and an affirmative vote of a majority of the other managing members who are not affiliates of the Company. As the Company does not possess control over any of these entities, the presumption of consolidation has been overcome pursuant to current accounting standards and the Company accounts for these investments under the equity method of accounting. Also included in equity method investments are the investments in (a) HealthCare Royalty Partners General Partners (b) an investment in the CBOE (Chicago Board Options Exchange) Stock Exchange LLC ("CBOE SE") representing a 7.2% stake in the exchange service provider for which the Company exercises significant influence over through representation on the CBOE Board of Directors, and (c) Starboard Value (and certain related parties) which serves as an operating company whose operations primarily include the day to day management (including portfolio management) of several activist hedge funds and related managed accounts. The Company recorded no impairment charges in relation to its equity method investments for the three and nine months ended September 30, 2015 and 2014. The Starboard Value entities were formed to provide a full range of investment advisory and management services and act as a general partner, investment advisor and pension advisor or in similar capacity to clients. In accordance with the respective offering documents of the underlying funds, Starboard Value entities are entitled to fixed percentages of management fees and performance fees. The Company holds a minority interest in the Starboard Value entities. The following table summarizes equity method investments held by the Company: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) RCG Longview Debt Fund IV Management, LLC $ 464 $ 676 RCG Longview Debt Fund V Partners, LLC 3,988 2,684 HealthCare Royalty GP, LLC 980 973 HealthCare Royalty GP II, LLC 1,260 1,125 HealthCare Royalty GP III, LLC 71 62 CBOE Stock Exchange, LLC 568 611 Starboard Value LP 30,079 48,772 RCG Longview Partners, LLC — 237 RCG Longview Management, LLC 1,287 1,117 RCG Urban American, LLC 122 422 RCG Urban American Management, LLC 379 379 RCG Longview Equity Management, LLC 250 316 Urban American Real Estate Fund II, LLC 1,975 2,329 RCG Kennedy House, LLC 268 509 Other 883 1,231 $ 42,574 $ 61,443 For the period ended September 30, 2015 , two equity method investment held by the Company met the significance criteria as defined under applicable SEC guidance. As such, the Company is required to present summarized financial information for these significant investees for the three and nine months ended September 30, 2015 and 2014. The summarized income statement information for the Company's investments in the individually significant investees is as follows: Other equity method investment Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (dollars in thousands) Revenues $ (3,216 ) $ 13,258 $ 8,249 $ 21,956 Expenses (2,033 ) (7,772 ) (1,927 ) (5,349 ) Net realized and unrealized gains (losses) (155 ) (40 ) 51 165 Net Income $ (5,404 ) $ 5,446 $ 6,373 $ 16,772 As of September 30, 2015 and December 31, 2014 , the Company's share of losses in its equity method investment in RCG Longview Partners II, LLC has exceeded the carrying amount recorded in this investee. These amounts are included in accounts payable, accrued expenses and other liabilities in the accompanying consolidated statements of financial condition. RCG Longview Partners II, LLC, as general partner to a real estate fund, has reversed previously recorded incentive income allocations and has recorded a current clawback obligation to the limited partners in the fund. This obligation is due to a change in unrealized value of the fund on which there have previously been distributed carried interest realizations; however, the settlement of a potential obligation is not due until the end of the life of the respective fund. As the Company is obligated to return previous distributions it received from RCG Longview Partners II, LLC, it has continued to record its share of gains/losses in the investee including reflecting its share of the clawback obligation in the amount of $6.2 million . The Company's income (loss) from equity method investments was $(5.9) million and $7.2 million for the three months ended September 30, 2015 and 2014 and $3.4 million and $17.5 million for the nine months ended September 30, 2015 and 2014 , respectively, and is included in net gains (losses) on securities, derivatives and other investments on the accompanying condensed consolidated statements of operations. (4) Lehman Claims, at fair value Lehman Brothers International (Europe) (“LBIE”), through certain affiliates, was a prime broker to the Company, and the Company held cash and cash equivalent balances with LBIE. On September 15, 2008, LBIE was placed into administration (the “Administration”) in the United Kingdom and, as a result, the assets held by the Company in its LBIE accounts were frozen at LBIE. The assets which the Company believed were held at LBIE at the time of Administration (the “Total Net Equity Claim”) consisted of $1.0 million , which represented an unsecured claim against LBIE. The total amounts received to date in respect of the Company’s unsecured claim against LBIE are approximately $1.0 million , representing 100.0% of its agreed claim. The Company may receive further distributions in respect of its claim, but the amount and timing of these distributions remains uncertain. The Company does not expect future distributions to be material. Securities sold, not yet purchased, at fair value Securities sold, not yet purchased, at fair value represent obligations of the Company to deliver a specified security at a contracted price and, thereby, create a liability to purchase that security at prevailing prices. The Company's liability for securities to be delivered is measured at their fair value as of the date of the consolidated financial statements. However, these transactions result in off-balance sheet risk, as the Company's ultimate cost to satisfy the delivery of securities sold, not yet purchased, at fair value may exceed the amount reflected in the accompanying consolidated statements of financial condition. Substantially all equity securities and options are pledged to the clearing broker under terms which permit the clearing broker to sell or re-pledge the securities to others subject to certain limitations. As of September 30, 2015 and December 31, 2014 , securities sold, not yet purchased, at fair value consisted of the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Common stocks $ 250,680 $ 207,815 Corporate bonds (a) 59 60 $ 250,739 $ 207,875 (a) As of September 30, 2015 and December 31, 2014 , the maturity was January 2026 with an interest rate of 5.55% . Securities lending and borrowing transactions The following tables present the contractual gross and net securities borrowing and lending agreements and the related offsetting amount, as of December 31, 2014 . During the first quarter of 2015 this business was completely liquidated. Gross amounts not offset in the Statement of Financial Condition Gross amounts recognized Gross amounts offset on the Consolidated Statements of Financial Condition (a) Net amounts included on the Consolidated Statements of Financial Condition Additional Amounts Available Financial instruments Cash Collateral pledged (b) Net amounts (dollars in thousands) As of December 31, 2014 Securities borrowed $ 676,100 $ — $ 676,100 $ (15,655 ) $ (660,445 ) $ — $ — Securities loaned 682,493 — 682,493 (2,441 ) (680,052 ) — — (a) Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred. (b) Includes the amount of cash collateral held/posted. Variable Interest Entities The total assets and liabilities of the variable interest entities for which the Company has concluded that it holds a variable interest, but for which it is not the primary beneficiary, are $3.2 billion and $415.6 million as of September 30, 2015 and $3.0 billion and $499.2 million as of December 31, 2014 , respectively. In addition, the maximum exposure relating to these variable interest entities as of September 30, 2015 was $314.6 million , and as of December 31, 2014 was $260.9 million , all of which is included in other investments, at fair value in the accompanying consolidated statements of financial condition. The exposure to loss primarily relates to the Consolidated Feeder Funds' investment in their Unconsolidated Master Funds as of September 30, 2015 and December 31, 2014 . b. Consolidated Funds Securities owned, at fair value As of September 30, 2015 , securities owned, at fair value, of $19.0 million represents various private investments in shares of preferred stock of biotechnology companies. Other investments, at fair value As of September 30, 2015 and December 31, 2014 other investments, at fair value, held by the Consolidated Funds are comprised of: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) (1) Portfolio Funds $ 255,896 $ 188,884 (2) Lehman claims — 493 $ 255,896 $ 189,377 Investments in Portfolio Funds, at fair value As of September 30, 2015 and December 31, 2014 , investments in Portfolio Funds, at fair value, included the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Investments of Enterprise LP $ 122,858 $ 138,253 Investments of Merger Fund 60,432 50,631 Investments of Quadratic LLC 72,606 — $ 255,896 $ 188,884 Consolidated investments of Enterprise LP Enterprise LP operates under a “master-feeder” structure, whereby Enterprise Master's shareholders are Enterprise LP and RCG II Intermediate Fund, L.P. The consolidated investments in Portfolio Funds include Enterprise LP's investment of $122.9 million and $138.3 million in Enterprise Master as of September 30, 2015 and December 31, 2014 , respectively. On May 12, 2010, the Company announced its intention to close Enterprise Master. Prior to this announcement, strategies utilized by Enterprise Master included merger arbitrage and activist investing, investments in distressed securities, convertible hedging, capital structure arbitrage, equity market neutral, investments in private placements of convertible securities, proprietary mortgages, structured credit investments, investments in mortgage backed securities and other structured finance products, investments in real estate and real property interests, structured private placements and other relative value strategies. Enterprise Master had broad investment powers and maximum flexibility in seeking to achieve its investment objective. Enterprise Master was permitted to invest in equity securities, debt instruments, options, futures, swaps, credit default swaps and other derivatives. As Enterprise Master winds down its positions, it will return capital to its investors. There are no unfunded commitments at Enterprise LP. Consolidated investments of Merger Fund The Merger Fund operates under a “master-feeder” structure, whereby Ramius Merger Master Ltd's ("Merger Master") shareholders are Merger Fund and Ramius Merger Fund Ltd. The consolidated investments in Portfolio Funds include Merger Fund's investment of $60.4 million and $50.6 million in Merger Master as of September 30, 2015 and December 31, 2014 , respectively. The Merger Master’s investment objective is to achieve consistent absolute returns while emphasizing the preservation of investor capital. The Merger Master seeks to achieve these objectives by taking a fundamental, research-driven approach to investing, primarily in the securities of issuers engaged in, or subject to, announced (or unannounced but otherwise anticipated) extraordinary corporate transactions, which may include, but are not limited to, mergers, acquisitions, leveraged buyouts, tender offers, hostile takeover bids, sale processes, exchange offers, and recapitalizations. Merger Master invests in the securities of one or more issuers engaged in or subject to such extraordinary corporate transactions. Merger Master typically seeks to derive a profit by realizing the price differential, or “spread,” between the market price of securities purchased or sold short and the market price or value of securities realized in connection with the completion or termination of the extraordinary corporate transaction, or in connection with the adjustment of market prices in anticipation thereof, while seeking to minimize the market risk associated with the aforementioned investment activities. Merger Master will, depending on markets conditions, generally focus the majority of its investment program on announced transactions. If the investment manager of Merger Master considers it necessary, it may either alone or as part of a group, also initiate shareholder actions seeking to maximize value. Such shareholder actions may include, but are not limited to, re-orienting management’s focus or initiating the sale of the company (or one or more of its divisions) to a third party. There are no unfunded commitments at Merger Fund. Consolidated investments of Quadratic Fund LLC Quadratic LLC operates under a “master-feeder” structure, whereby Quadratic Master Fund Ltd's ("Quadratic Master") shareholders are Quadratic Fund LLC and Quadratic Fund Ltd. The consolidated investments in Portfolio Funds include Quadratic Fund LLC's investment of $72.6 million in Quadratic Master as of September 30, 2015 . The Quadratic Master’s investment objective is to achieve attractive, risk-adjusted rates of return through the use of proprietary fundamental global macro and options/swaptions based strategies. Quadratic Master’s strategy is primarily executed via options and swaptions. Quadratic Master will pursue absolute returns in all market environments. Occasionally, Quadratic Master may use dividend swaps, credit default swaps, interest rate swaps, inflation swaps, futures, foreign currency forwards, tranches and other delta one products as a hedge against existing options positions or when the investment manager believes that the payoff possibilities thereof are sufficiently asymmetric as to exhibit option-like qualities. There are no unfunded commitments at Quadratic Fund. (2) Lehman Claims, at fair value With respect to the aforementioned Lehman claims, the Total Net Equity Claim of Enterprise Master based on the value of assets at the time of Lehman's insolvency held directly by Enterprise Master and through Enterprise Master's ownership interest in affiliated funds consisted of $24.3 million . As of September 30, 2015 , Enterprise Master has received distributions totaling approximately $37.2 million in respect of its claim. Enterprise Master does not expect to receive any further distributions in respect of its claim. Indirect Concentration of the Underlying Investments Held by Consolidated Funds From time to time, either directly or indirectly through its investments in the Consolidated Funds, the Company may maintain exposure to a particular issue or issuer (both long and/or short) which may account for 5% or more of the Company's equity. Based on information that is available to the Company as of September 30, 2015 and December 31, 2014 , the Company assessed whether or not its interests in an issuer for which the Company's pro-rata share exceeds 5% of the Company's equity. There were no indirect concentrations that exceed 5% of the Company's equity as of September 30, 2015 and December 31, 2014 . Underlying Investments of Unconsolidated Funds Held by Consolidated Funds Enterprise Master and Merger Master Enterprise LP's investment in Enterprise Master represents Enterprise LP's proportionate share of Enterprise Master's net assets; as a result, the investment balances of Enterprise Master reflected below may exceed the net investment which Enterprise LP has recorded. Merger Fund's investment in Merger Master represents Merger Fund's proportionate share of Merger Master's net assets; as a result, the investment balances of Merger Master reflected below may exceed the net investment which Merger Fund has recorded. The following tables present summarized investment information for the underlying investments and derivatives held by Enterprise Master and Merger Master as of September 30, 2015 and December 31, 2014 : Securities owned by Enterprise Master, at fair value As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Bank debt $ — $ 20 Common stock 1,657 1,659 Preferred stock 626 576 Private equity — 587 Restricted stock 124 124 Rights 2,715 2,802 Trade claims 128 128 $ 5,250 $ 5,896 Receivable/(Payable) on derivative contracts, at fair value, owned by Enterprise Master As of September 30, 2015 As of December 31, 2014 Description (dollars in thousands) Currency forwards $ (4 ) $ 64 $ (4 ) $ 64 Portfolio Funds, owned by Enterprise Master, at fair value As of September 30, 2015 As of December 31, 2014 Strategy (dollars in thousands) RCG Longview Equity Fund, LP* Real Estate $ 7,637 $ 9,090 RCG Longview II, LP* Real Estate 785 747 RCG Longview Debt Fund IV, LP* Real Estate 3,999 5,348 RCG Longview, LP* Real Estate — 40 RCG Soundview, LLC* Real Estate 452 452 RCG Urban American Real Estate Fund, L.P.* Real Estate 648 1,161 RCG International Sarl* Multi-Strategy 1,220 2,113 RCG Special Opportunities Fund, Ltd* Multi-Strategy 89,303 92,405 RCG Energy, LLC * Energy 1,398 2,294 RCG Renergys, LLC* Energy 1 1 Other Private Investments Various 10,629 12,057 Other Real Estate Investments (*) Real Estate 5,731 10,138 $ 121,803 $ 135,846 * Affiliates of the Company. Merger Master Securities owned by Merger Master, at fair value As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Common stocks $ 179,650 $ 133,510 Corporate bonds (a) — 3,383 $ 179,650 $ 136,893 (a) As of December 31, 2014 , maturities ranged from February 2017 to June 2019 and interest rates ranged between 8.50% and 9.75% . Securities sold, not yet purchased, by Merger Master, at fair value As of September 30, 2015 and December 31, 2014 , Merger Master held common stock, sold not yet purchased, of $57.7 million and $39.9 million , respectively. Receivable on derivative contracts, at fair value, owned by Merger Master As of September 30, 2015 As of December 31, 2014 Description (dollars in thousands) Options $ 604 $ 541 Currency forwards 22 — Equity swaps 150 76 $ 776 $ 617 Payable for derivative contracts, at fair value, owned by Merger Master As of September 30, 2015 As of December 31, 2014 Description (dollars in thousands) Options $ 36 $ 238 Exchange traded fund 3,801 — Equity swaps 862 56 $ 4,699 $ 294 Quadratic Master Securities owned by Quadratic Master, at fair value As of September 30, 2015 (dollars in thousands) Common stocks $ 267 U.S. Government securities (a) 15,000 $ 15,267 (a) As of September 30, 2015 , the maturity was October 2015 with an interest rate of 0% . The Company's long and short exposure to derivatives is as follows: Receivable on derivative contracts, at fair value, owned by Quadratic Master As of September 30, 2015 Description (dollars in thousands) Options $ 9,622 Currency forwards 32 $ 9,654 As of September 30, 2015 , Quadratic Master held options payable for derivative, of $0.1 million .

Fair Value Measurements for Ope

Fair Value Measurements for Operating Entities and Consolidated Funds	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements for Operating Entities and Consolidated Funds	Fair Value Measurements for Operating Entities and Consolidated Funds The following table presents the assets and liabilities that are measured at fair value on a recurring basis on the accompanying consolidated statements of financial condition by caption and by level within the valuation hierarchy as of September 30, 2015 and December 31, 2014 : Assets at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (dollars in thousands) Operating Entities Securities owned US Government securities $ 3,015 $ — $ — $ 3,015 Preferred stock — — 15,771 15,771 Common stocks 689,252 22,920 317 712,489 Convertible bonds — — 1,129 1,129 Corporate bonds — 113,585 — 113,585 Warrants and rights 877 — 2,994 3,871 Mutual funds 14,825 — — 14,825 Receivable on derivative contracts, at fair value — Futures 68 — — 68 Currency forwards — 105 — 105 Equity swaps — 470 — 470 Options 10,277 9,076 21,591 40,944 Other investments Real estate investments — — 1,916 1,916 Lehman claim — — 335 335 Consolidated funds Preferred stock — — 19,000 19,000 $ 718,314 $ 146,156 $ 63,053 $ 927,523 Percentage of total assets measured at fair value 77.4 % 15.8 % 6.8 % Portfolio funds measured at net asset value (a) 108,509 Consolidated funds' portfolio funds measured at net asset value (a) 255,896 Equity method investments 42,574 Total investments $ 1,334,502 Liabilities at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (dollars in thousands) Securities sold, not yet purchased Common stocks $ 250,680 $ — $ — $ 250,680 Corporate bonds — 59 — 59 Payable for derivative contracts, at fair value Futures 381 — — 381 Currency forwards 107 — 107 Equity and credit default swaps 2,615 — 2,615 Options 1,384 — 21,591 22,975 Accounts payable, accrued expenses and other liabilities Contingent consideration liability (b) — — 5,458 5,458 $ 252,445 $ 2,781 $ 27,049 $ 282,275 Percentage of total liabilities measured at fair value 89.4 % 1.0 % 9.6 % (a) In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition. (b) In accordance with the terms of the purchase agreements for acquisitions that closed during 2012 and the third quarter of 2015, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the periods ended August 2016 and December 2020, respectively. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts as of September 30, 2015 can range from zero to $6.7 million . Assets at Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total (dollars in thousands) Operating Entities Securities owned US Government securities $ 2,010 $ — $ — $ 2,010 Preferred stock — 2,553 12,517 15,070 Common stocks 578,934 18,130 412 597,476 Convertible bonds — — 900 900 Corporate bonds — 159,557 — 159,557 Warrants and rights 95 — 1,322 1,417 Mutual funds 15,776 — — 15,776 Receivable on derivative contracts, at fair value Futures 75 — — 75 Currency forwards — 310 — 310 Equity swaps — 251 — 251 Options 10,462 1,972 36,807 49,241 Other investments Real estate investments — — 2,175 2,175 Lehman claim — — 380 380 Consolidated funds Lehman claim — — 493 493 $ 607,352 $ 182,773 $ 55,006 $ 845,131 Percentage of total assets measured at fair value 71.9 % 21.6 % 6.5 % Portfolio funds measured at net asset value (a) 103,466 Consolidated funds' portfolio funds measured at net asset value (a) 188,884 Equity method investments 61,443 Total investments $ 1,198,924 Liabilities at Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total (dollars in thousands) Securities sold, not yet purchased Common stocks $ 207,815 $ — $ — $ 207,815 Corporate bonds — 60 — 60 Payable for derivative contracts, at fair value Futures 33 — — 33 Equity and credit default swaps — 1,603 — 1,603 Options 2,887 — 36,807 39,694 Accounts payable, accrued expenses and other liabilities Contingent consideration liability (b) — — 4,083 4,083 $ 210,735 $ 1,663 $ 40,890 $ 253,288 Percentage of total liabilities measured at fair value 83.2 % 0.7 % 16.1 % (a) In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition. (b) In accordance with the terms of a purchase agreement for an acquisitions that closed during 2012, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the period ended August 2016. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts can range from $0.9 million to $7.1 million . The following table includes a rollforward of the amounts for the three and nine months ended September 30, 2015 and 2014 , for financial instruments classified within level 3. The classification of a financial instrument within level 3 is based upon the significance of the unobservable inputs to the overall fair value measurement. Three Months Ended September 30, 2015 Balance at June 30, 2015 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2015 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 23,462 $ — $ (9,000 ) (a) (b) $ 3,500 $ (6,665 ) $ 4,474 $ 15,771 $ 1,200 Common stocks 404 — — 104 (89 ) (102 ) 317 (87 ) Convertible bonds 879 — — 250 — — 1,129 — Options, asset 58,576 — — — — (36,985 ) 21,591 (36,985 ) Options, liability 58,576 — — — — (36,985 ) 21,591 (36,985 ) Warrants and rights 2,316 — — — — 678 2,994 878 Real estate 1,987 — — — (70 ) (1 ) 1,916 (1 ) Lehman claim 347 — — — — (12 ) 335 (12 ) Contingent consideration liability 2,358 — — 3,100 — — 5,458 — Consolidated Funds Preferred stock — — 7,000 (b) 12,000 — — 19,000 — Lehman claim 744 — — — (739 ) (5 ) — — Three Months Ended September 30, 2014 Balance at June 30, 2014 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2014 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 2,574 $ — $ (2,000 ) (a) $ — $ — $ — $ 574 $ — Common stocks 419 — — — (1 ) (128 ) 290 (14 ) Convertible bonds 1,750 — — — — — 1,750 — Options, asset 37,658 — — — — (8,873 ) 28,785 (8,873 ) Options, liability 37,658 — — — — (8,873 ) 28,785 (8,873 ) Warrants and rights 3,346 — — 57 (57 ) (738 ) 2,608 (434 ) Real estate 2,262 — — — — 23 2,285 23 Lehman claim 418 — — — — (58 ) 360 (58 ) Contingent consideration liability 6,783 — — — (364 ) — 6,419 — Consolidated Funds Lehman claim 4,090 — — — (3,731 ) 2 361 2 Nine Months Ended September 30, 2015 Balance at December 31, 2014 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2015 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 12,517 $ — $ (15,823 ) (a) (b) $ 21,750 $ (6,665 ) $ 3,992 $ 15,771 $ 717 Common stocks 412 — — 104 (120 ) (79 ) 317 (74 ) Convertible bonds 900 — — 250 — (21 ) 1,129 (21 ) Options, asset 36,807 — — — — (15,216 ) 21,591 (15,216 ) Options, liability 36,807 — — — — (15,216 ) 21,591 (15,216 ) Warrants and Rights 1,322 — — 26 (71 ) 1,717 2,994 1,757 Real estate 2,175 — — — (377 ) 118 1,916 118 Lehman claim 380 — — — — (45 ) 335 (45 ) Contingent consideration liability 4,083 — — 3,100 (1,725 ) — 5,458 — Consolidated Funds Preferred stock — — 7,000 (b) 12,000 — — 19,000 — Lehman claim 493 — — — (739 ) 246 — — Nine Months Ended September 30, 2014 Balance at December 31, 2013 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2014 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 324 $ — $ (2,000 ) (a) $ 2,250 $ — $ — $ 574 $ — Common stocks 3,559 — (3,150 ) (a) 9 (1 ) (127 ) 290 (13 ) Convertible bonds 1,950 — — — (200 ) — 1,750 — Options, asset — — — 35,710 — (6,925 ) 28,785 (6,925 ) Options, liability — — — 35,710 — (6,925 ) 28,785 (6,925 ) Warrants and Rights, asset 5,805 — — 57 (1,385 ) (1,869 ) 2,608 (432 ) Real estate 2,088 — — 50,000 (50,027 ) 224 2,285 224 Lehman claim 378 — — — (76 ) 58 360 58 Contingent consideration liability 6,937 — — — (518 ) — 6,419 — Consolidated Funds Lehman claim 4,842 — — — (4,711 ) 230 361 230 (1) Unrealized gains/losses are reported in other income (loss) in the accompanying consolidated statements of operations. (a) The company completed an initial public offering. (b) The company transferred investments to a consolidated fund. All realized and unrealized gains (losses) in the table above are reflected in other income (loss) in the accompanying consolidated statements of operations. Certain assets and liabilities are measured at fair value on a nonrecurring basis and therefore are not included in the tables above. The Company recognizes all transfers and the related unrealized gain (loss) at the beginning of the reporting period. Transfers between level 1 and 2 generally relate to whether the principal market for the security becomes active or inactive. Transfers between level 2 and 3 generally relate to whether significant relevant observable inputs are available for the fair value measurements or due to change in liquidity restrictions for the investments. During the three and nine months ended September 30, 2015 and 2014, there were no transfers between level 1 and level 2 assets and liabilities. The following table includes quantitative information as of September 30, 2015 and December 31, 2014 for financial instruments classified within level 3. The table below quantifies information about the significant unobservable inputs used in the fair value measurement of the Company's level 3 financial instruments. Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30, 2015 Valuation techniques Unobservable Inputs Range Level 3 Assets (dollars in thousands) Common and preferred stocks $ 3,110 Market/transaction multiples and option pricing method Volatility Market multiples 42% 1x to 5.25x Convertible bonds 1,129 Recovery analysis Recovery rate 50% Warrants and rights, net 2,994 Model based Volatility 17% to 60% (weighted average 29%) Options 21,591 Option pricing models Volatility 29% Other level 3 assets (a) 34,229 Total level 3 assets 63,053 Level 3 Liabilities Options 21,591 Option pricing models Volatility 29% Contingent consideration 5,458 Discounted cash flows Projected cash flow and discount rate 9% - 24.5% (weighted average 18%) Total level 3 liabilities $ 27,049 Quantitative Information about Level 3 Fair Value Measurements Fair Value at December 31, 2014 Valuation techniques Unobservable Inputs Range Level 3 Assets (dollars in thousands) Common and preferred stocks $ 12,269 Market multiples and option pricing method Volatility Market multiples 45% 1x to 6x Convertible bonds 900 Recovery analysis Recovery rate 50% Warrants and rights, net 1,322 Model based Volatility 20% to 60% (weighted average 34%) Options 36,807 Option pricing models Volatility Credit spreads 30% to 40% 500bps - 750 bps Other level 3 assets (a) 3,708 Total level 3 assets 55,006 Level 3 Liabilities Options 36,807 Option pricing models Volatility Credit spreads 30% to 40% 500bps - 750 bps Contingent consideration 4,083 Discounted cash flows Projected cash flow and discount rate 9% Total level 3 liabilities $ 40,890 (a) The quantitative disclosures exclude financial instruments for which the determination of fair value is based on prices from prior transactions and investments for which NAV per share is used as a practical expedient to determine fair value. The Company has established valuation policies and procedures and an internal control infrastructure over its fair value measurement of financial instruments which includes ongoing oversight by the valuation committee as well as periodic audits performed by the Company's internal audit group. The valuation committee is comprised of senior management, including non-investment professionals, who are responsible for overseeing and monitoring the pricing of the Company's investments, including the review of the results of the independent price verification process, approval of new trading asset classes and use of applicable pricing models and approaches. The US GAAP fair value leveling hierarchy is designated and monitored on an ongoing basis. In determining the designation, the Company takes into consideration a number of factors including the observability of inputs, liquidity of the investment and the significance of a particular input to the fair value measurement. Designations, models, pricing vendors, third party valuation providers and inputs used to derive fair market value are subject to review by the valuation committee and the internal audit group. The Company reviews its valuation policy guidelines on an ongoing basis and may adjust them in light of, improved valuation metrics and models, the availability of reliable inputs and information, and prevailing market conditions. The Company reviews a daily profit and loss report, as well as other periodic reports, and analyzes material changes from period-to-period in the valuation of its investments as part of its control procedures. The Company also performs back testing on a regular basis by comparing prices observed in executed transactions to previous valuations. The fair market value for level 3 securities may be highly sensitive to the use of industry standard models, unobservable inputs and subjective assumptions. The degree of fair market value sensitivity is also contingent upon the subjective weight given to specific inputs and valuation metrics. The Company holds various equity and debt instruments where different weight may be applied to industry standard models representing standard valuation metrics such as: discounted cash flows, market multiples, comparative transactions, capital rates, recovery rates and timing, and bid levels. Generally, changes in the weights ascribed to the various valuation metrics and the significant unobservable inputs in isolation may result in significantly lower or higher fair value measurements. Volatility levels for warrants and options are not readily observable and subject to interpretation. Changes in capital rates, discount rates and replacement costs could significantly increase or decrease the valuation of the real estate investments. The interrelationship between unobservable inputs may vary significantly amongst level 3 securities as they are generally highly idiosyncratic. Significant increases (decreases) in any of those inputs in isolation can result in a significantly lower (higher) fair value measurement. Other financial assets and liabilities at fair value The following table presents the carrying values and fair values, at September 30, 2015 and December 31, 2014 , of financial assets and liabilities and information on their classification within the fair value hierarchy which are not measured at fair value on a recurring basis. For additional information regarding the financial instruments within the scope of this disclosure, and the methods and significant assumptions used to estimate their fair value see Note 3 . September 30, 2015 December 31, 2014 Fair Value Hierarchy Carrying Amount Fair Value Carrying Amount Fair Value (dollars in thousands) Financial Assets Operating companies Cash and cash equivalents $ 92,854 $ 92,854 $ 129,509 $ 129,509 Level 1 Cash collateral pledged 9,129 9,129 8,306 8,306 Level 2 Securities borrowed — — 676,100 660,445 Level 1 Consolidated funds Cash and cash equivalents 16,625 16,625 501 501 Level 1 Financial Liabilities Securities loaned — — 682,493 661,533 Level 1 Convertible debt 123,149 (a) 158,470 (b) 118,475 (a) 160,713 (b) Level 2 Notes payable and other debt 66,628 69,436 67,144 69,548 Level 2 (a) The carrying amount of the convertible debt includes an unamortized discount of $26.4 million and $31.0 million as of September 30, 2015 and December 31, 2014 . (b) The convertible debt include the conversion option and is based on the last broker quote available.

Receivables from and Payable to

Receivables from and Payable to Brokers	9 Months Ended
	Sep. 30, 2015
Brokers and Dealers [Abstract]
Receivables from and Payable to Brokers	Receivables from and Payable to Brokers Receivables from and payable to brokers includes cash held at the clearing brokers, amounts receivable or payable for unsettled transactions, monies borrowed and proceeds from short sales (including commissions and fees related to securities transactions) equal to the fair value of securities sold, not yet purchased, which are restricted until the Company purchases the securities sold short. Pursuant to the master netting agreements the Company entered into with its brokers, these balances are presented net (assets less liabilities) across balances with the same broker. As of September 30, 2015 and December 31, 2014 , receivable from brokers was $115.3 million and $84.7 million , respectively. Payable to brokers was $328.9 million and $ 335.8 million as of September 30, 2015 and December 31, 2014 , respectively. The Company's receivables from and payable to brokers balances are held at multiple financial institutions.

Goodwill and Intangibles

Goodwill and Intangibles	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	Goodwill and Intangibles In accordance with US GAAP, the Company tests goodwill for impairment on an annual basis or at an interim period if events or changed circumstances would more likely than not reduce the fair value of a reporting unit below its carrying amount. Under US GAAP, the Company first assesses the qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amounts as a basis for determining if it is necessary to perform the two-step approach. Periodically estimating the fair value of a reporting unit requires significant judgment and often involves the use of significant estimates and assumptions. These estimates and assumptions could have a significant effect on whether or not an impairment charge is recorded and the magnitude of such a charge. In connection with the Cowen Prime transaction, the Company recognized goodwill of $9.3 million and intangible assets (including customer relationships, trade name and non-compete arrangements) with an estimated fair value of $8.5 million which are included within Intangible assets, net in the condensed consolidation statements of financial condition with the expected useful lives ranging from 1 to 9 years with a weighted average useful life of 7.7 years . Amortization expense related to intangibles from the Cowen Prime acquisition for the three and nine months ended September 30, 2015 is $0.1 million respectively. No impairment charges for goodwill were recognized during the three and nine months ended September 30, 2015 and 2014 , respectively.

Redeemable Non-Controlling Inte

Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds	9 Months Ended
	Sep. 30, 2015
Noncontrolling Interest [Abstract]
Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds	Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds Redeemable non-controlling interests in consolidated subsidiaries and funds and the related net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds are comprised as follows: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Redeemable non-controlling interests in consolidated subsidiaries and funds Operating companies $ 15,730 $ 9,619 Consolidated funds 155,515 76,457 $ 171,245 $ 86,076 Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (dollars in thousands) Income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds Operating companies $ 4,577 $ 3,223 $ 8,669 $ 9,690 Consolidated funds (233 ) 783 2,311 3,719 $ 4,344 $ 4,006 $ 10,980 $ 13,409

Share-Based Compensation and Em

Share-Based Compensation and Employee Ownership Plans	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation and Employee Ownership Plans	Share-Based and Deferred Compensation and Employee Ownership Plans The Company issues share based compensation under the 2006 Equity and Incentive Plan, the 2007 Equity and Incentive Plan (both established prior to the November 2009 transaction between Ramius and Cowen) and the Cowen Group, Inc. 2010 Equity and Incentive Plan (collectively, the “Equity Plans”). The Equity Plans permit the grant of options, restricted shares, restricted stock units, stock appreciation rights ("SAR's") and other equity based awards to the Company's employees and directors. Stock options granted generally vest over two -to- five -year periods and expire seven years from the date of grant. Restricted shares and restricted share units issued may be immediately vested or may generally vest over a two -to- five -year period. SAR's vest and expire after five years from grant date. Awards are subject to the risk of forfeiture. As of September 30, 2015 , there were approximately 4.2 million shares available for future issuance under the Equity Plans. Under the 2010 Equity Plan, the Company awarded $12.5 million of deferred cash awards to its employees during the nine months ended September 30, 2015 . These awards vest over a four year period and accrue interest between 0.70% to 0.75% per year. As of September 30, 2015 , the Company had unrecognized compensation expense related to deferred cash awards of $32.4 million . The Company measures compensation cost for share based awards according to the equity method. In accordance with the expense recognition provisions of those standards, the Company amortizes unearned compensation associated with share based awards on a straight-line basis over the vesting period of the option or award. In relation to awards under the Equity Plans, the Company recognized expense of $5.3 million and $3.8 million for the three months ended September 30, 2015 and 2014 and $16.2 million and $14.3 million for the nine months ended September 30, 2015 and 2014 , respectively. The income tax effect recognized for the Equity Plans was a benefit of $2.1 million and $1.4 million for the three months ended September 30, 2015 and 2014 and $2.8 million and $4.4 million for the nine months ended September 30, 2015 and 2014 , respectively. However, for the three and nine months ended September 30, 2014, the Company recorded a valuation allowance against these tax benefits. Stock Options and Stock Appreciation Rights The Company values options and SAR's on grant date using the Black-Scholes valuation model which requires the Company to make assumptions regarding the expected term, volatility, risk-free rate and dividend yield: Expected term . Expected term represents the period of time that awards granted are expected to be outstanding. The Company elected to use the "simplified" calculation method, as applicable to companies that lack extensive historical data. The mid-point between the vesting date and the contractual expiration date is used as the expected term under this method. Expected volatility . The Company bases its expected volatility on its own stock price history. Risk free rate . The risk-free rate for periods within the expected term of the award is based on the interest rate of a traded zero-coupon U.S. Treasury bond with a term equal to the awards' expected term on the date of grant. Dividend yield . The Company has not paid and does not expect to pay dividends in the foreseeable future. Accordingly, the assumed dividend yield is zero . The following table summarizes the Company's stock option activity for the nine months ended September 30, 2015 : Shares Subject Weighted Average Weighted Average Aggregate Intrinsic (in years) (dollars in thousands) Balance outstanding at December 31, 2014 216,672 $ 5.65 1.60 $ 87 Options granted — — — — Options exercised (100,002 ) 3.96 — — Options expired (100,003 ) 7.49 — — Balance outstanding at September 30, 2015 16,667 $ 4.89 1.35 $ — Options exercisable at September 30, 2015 16,667 $ 4.89 1.35 $ — (1) Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014 . As of September 30, 2015 , the unrecognized compensation expense related to the Company's grant of stock options was insignificant. The following table summarizes the Company's SAR's for the nine months ended September 30, 2015 : Shares Subject Weighted Average Weighted Average Aggregate Intrinsic (in years) (dollars in thousands) Balance outstanding at December 31, 2014 400,000 $ 2.90 3.21 $ 913 SAR's granted — — — — SAR's acquired — — — — SAR's expired — — — — Balance outstanding at September 30, 2015 400,000 $ 2.90 2.46 $ 781 SAR's exercisable at September 30, 2015 — $ — — $ — (1) Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014 . As of September 30, 2015 and December 31, 2014 , the unrecognized compensation expense related to the Company's grant of SAR's was $0.2 million and $0.2 million , respectively. Restricted Shares and Restricted Stock Units Granted to Employees Restricted shares and restricted stock units are referred to collectively as restricted stock. The following table summarizes the Company's restricted share and restricted stock unit activity for the nine months ended September 30, 2015 : Nonvested Restricted Shares and Restricted Stock Units Weighted-Average Balance outstanding at December 31, 2014 17,654,582 $ 3.70 Granted 5,718,605 4.79 Vested (3,992,005 ) 3.08 Canceled — — Forfeited (1,017,758 ) 3.41 Balance outstanding at September 30, 2015 (1) 18,363,424 $ 4.19 (1) Performance linked restricted stock units of 1,925,750 were awarded to employees of the Company in December 2013 and January 2014. Of the awards granted, 326,250 have been forfeited through September 30, 2015 . The remaining awards, included in the outstanding balance as of September 30, 2015 , will vest on June 10, 2019 and will be earned only to the extent that the Company attains specified performance goals relating to its volume-weighted average share price and the aggregate net income for the years from 2014 to 2018. The actual number of RSUs ultimately earned could vary from zero, if performance goals are not met, to as much as 100% of the targeted award. Each RSU is equal to the one share of the Company’s Class A common stock. Compensation expense is recognized to the extent that it is probable that the Company will attain the performance goals. The fair value of restricted stock (excluding performance linked units which are valued using the Monte Carlo valuation model) is determined based on the number of shares granted and the quoted price of the Company's common stock on the date of grant. As of September 30, 2015 , there was $52.7 million of unrecognized compensation expense related to the Company's grant of nonvested restricted shares and restricted stock units to employees. Unrecognized compensation expense related to nonvested restricted shares and restricted stock units granted to employees is expected to be recognized over a weighted-average period of 1.66 years. Restricted Shares and Restricted Stock Units Granted to Non-employee Board Members There were 157,621 restricted stock units awarded during the nine months ended September 30, 2015 . As of September 30, 2015 there were 497,570 restricted stock units outstanding.

Defined Benefit Plan

Defined Benefit Plan	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Plan	Defined Benefit Plan On December 1, 2005, the Company adopted a defined benefit plan ("Cash Balance Plan") to provide retirement income to all eligible employees of the Company and its subsidiaries in accordance with the terms and conditions in the Cash Balance Plan. The Company made the decision to terminate the Cash Balance Plan effective December 31, 2013. On May 12, 2014 Cowen received a favorable determination letter from the IRS approving the termination of the Cash Balance Plan. Subsequently, steps were taken to process the distributions based on participant distribution elections by December 15, 2014 and the Company will file a final Form 5500 for the Plan Year 2014. The amounts contained in the following table relate to the Company's defined benefit plan(s) for the three and nine months ended September 30, 2014 : Three Months Ended September 30, 2014 Nine Months Ended September 30, 2014 (dollars in thousands) Components of net periodic benefit cost included in employee compensation and benefits Service cost $ — $ — Interest cost 18 85 Expected return on plan assets (168 ) (300 ) Amortization of loss / (gain) (7 ) (7 ) Amortization of prior service cost — — Effect of settlement — — Net periodic benefit cost $ (157 ) $ (222 )

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The taxable results of the Company’s U.S. operations are included in the consolidated income tax returns of Cowen Group, Inc. as well as stand-alone state and local tax returns. The Company has subsidiaries that are resident in foreign countries where tax filings have to be submitted on a stand‑alone basis. These subsidiaries are subject to tax in their respective countries and the Company is responsible for and, thus, reports all taxes incurred by these subsidiaries. The countries where the Company owns subsidiaries that file tax returns are United Kingdom, Luxembourg, Gibraltar, and Hong Kong. The Company calculates its U.S. tax provision using the estimated annual effective tax rate methodology. The tax expense or benefit caused by an unusual or infrequent item is recorded in the quarter in which it occurs. The Company uses the discrete methodology to calculate its income tax provision for its foreign subsidiaries. Based on these methodologies, the Company’s effective income tax rate was 17.81% and 0.69% for the nine months ended September 30, 2015 and 2014, respectively. During the nine months ended September 30, 2015 , the unusual or infrequent items whose tax impact were recorded discretely related primarily to state taxes, the impact of change in tax legislation in New York and the tax provisions of the Company’s foreign subsidiaries. For the nine months ended September 30, 2015 , the effective tax rate differs from the statutory rate of 35% primarily due to state taxes, stock compensation and other nondeductible expenses. For the nine months ended September 30, 2014, the effective tax rate differs from the statutory rate of 35% primarily due to a change in the Company's valuation allowance, stock compensation and other nondeductible expenses. The Company records deferred tax assets and liabilities for the future tax benefit or expense that will result from differences between the carrying value of its assets for income tax purposes and for financial reporting purposes, as well as for operating or capital loss and tax credit carryovers. A valuation allowance is recorded to bring the net deferred tax assets to a level that, in management's view, is more likely than not to be realized in the foreseeable future. This level will be estimated based on a number of factors, especially the amount of net deferred tax assets of the Company that are actually expected to be realized, for tax purposes, in the foreseeable future. As of September 30, 2015 , the Company recorded no valuation allowance against its net deferred tax assets. The Company is subject to examination by the United States Internal Revenue Service, the United Kingdom Inland Revenue Service as well as state, local and foreign tax authorities in jurisdictions where the Company has significant business operations, such as New York. Currently, the Company is under audit by New York State for the 2010 to 2012 tax years. Management is not expecting a material tax liability from this audit. The Company intends to permanently reinvest the capital and accumulated earnings of its foreign subsidiaries in the respective subsidiary, but remits the current earnings of its foreign subsidiaries to the United States to the extent permissible under local regulatory rules. The undistributed earnings of the Company’s foreign subsidiaries totaled $0.8 million and $1.1 million as of September 30, 2015 and December 31, 2014 , respectively, and the tax liability that would arise if these earnings were remitted to the United States would be approximately $0.1 million and $0.2 million , respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Obligations The Company has entered into leases for office space and equipment. These leases contain rent escalation clauses. The Company records rent expense on a straight-line basis over the lease term, including any rent holiday periods. Rent expense was $4.6 million and $4.3 million for the three months ended September 30, 2015 and 2014 and $13.3 million and $12.5 million , for the nine months ended September 30, 2015 and 2014 , respectively. As of September 30, 2015 , future minimum annual lease and service payments for the Company were as follows: Equipment Leases (a) Service Payments Facility Leases (b) (dollars in thousands) 2015 $ 700 $ 4,490 $ 5,094 2016 2,502 12,391 19,401 2017 2,301 6,245 16,030 2018 2,221 4,162 15,621 2019 813 1,375 14,822 Thereafter — — 47,064 $ 8,537 $ 28,663 $ 118,032 (a) Equipment Leases include the Company's commitments relating to operating and capital leases. See Note 14 for further information on the capital lease minimum payments which are included in the table. (b) The Company has entered into various agreements to sublease certain of its premises. The Company recorded sublease income related to these leases of $0.5 million and $0.5 million for the three months ended September 30, 2015 and 2014 and $1.4 million and $1.3 million for the nine months ended September 30, 2015 and 2014 , respectively. Clawback Obligations For financial reporting purposes, the general partners of a real estate fund have recorded a liability for potential clawback obligations to the limited partners, due to changes in the unrealized value of the fund's remaining investments and where the fund's general partner has previously received carried interest distributions. The clawback liability, however, is not realized until the end of the fund's life. The life of the real estate fund's with a potential clawback obligation is currently in a winding-up phase whereby the remaining assets of the fund are being liquidated as promptly as possible so as to maximize value, however a final date for liquidation has not been set. The fund is currently winding-down and as of both September 30, 2015 and December 31, 2014 , and the clawback obligation was $6.2 million . The Company serves as the general partner/managing member and/or investment manager to various affiliated and sponsored funds. As such, the Company is contingently liable for obligations for those entities. These amounts are not included above as the Company believes that the assets in these funds are sufficient to discharge any liabilities. Unfunded Commitments As of September 30, 2015 , the Company had unfunded commitments of $9.6 million pertaining to capital commitments in four real estate investments held by the Company, all of which pertain to related party investments. Such commitments can be called at any time, subject to advance notice. The Company, as a limited partner of the HealthCare Royalty Partners funds and also as a member of HealthCare Royalty Partners General Partners, has committed to invest $45.4 million in the Healthcare Royalty Partners funds which are managed by Healthcare Royalty Management. This commitment is expected to be called over a two to five year period. The Company will make its pro-rata investment in the HealthCare Royalty Partners funds along with the other limited partners. Through September 30, 2015 , the Company has funded $36 million towards these commitments. In April 2013, the Company committed $1.0 million t o Starboard Leaders Fund LP, which may increase or decrease over time, and, as of September 30, 2015 , has funded $0.9 million towards this commitment. As of September 30, 2015 , the Company has an unfunded commitment to Formation8 Partners Fund I, L.P. of $1.4 million . The remaining capital commitment is expected to be called over a one year period . As of September 30, 2015, the Company has an unfunded commitme n t to Formation 8 Partners Hardware Fund I, L.P. of $1.1 million . The remaining capital commitment is expected to be called over a one year peri od. Litigation In the ordinary course of business, the Company and its affiliates and subsidiaries and current and former officers, directors and employees (the "Company and Related Parties") are named as defendants in, or as parties to, various legal actions and proceedings. Certain of these actions and proceedings assert claims or seek relief in connection with alleged violations of securities, banking, anti-fraud, anti-money laundering, employment and other statutory and common laws. Certain of these actual or threatened legal actions and proceedings include claims for substantial or indeterminate compensatory or punitive damages, or for injunctive relief. In the ordinary course of business, the Company and Related Parties are also subject to governmental and regulatory examinations, information gathering requests (both formal and informal), certain of which may result in adverse judgments, settlements, fines, penalties, injunctions or other relief. Certain affiliates and subsidiaries of the Company are investment banks, registered broker-dealers, futures commission merchants, investment advisers or other regulated entities and, in those capacities, are subject to regulation by various U.S., state and foreign securities, commodity futures and other regulators. In connection with formal and informal inquiries by these regulators, the Company and such affiliates and subsidiaries receive requests, and orders seeking documents and other information in connection with various aspects of their regulated activities. Due to the global scope of the Company's operations, and its presence in countries around the world, the Company and Related Parties may be subject to litigation, and governmental and regulatory examinations, information gathering requests, investigations and proceedings (both formal and informal), in multiple jurisdictions with legal and regulatory regimes that may differ substantially, and present substantially different risks, from those the Company and Related Parties are subject to in the United States. The Company seeks to resolve all litigation and regulatory matters in the manner management believes is in the best interests of the Company and its shareholders, and contests liability, allegations of wrongdoing and, where applicable, the amount of damages or scope of any penalties or other relief sought as appropriate in each pending matter. In accordance with US GAAP, the Company establishes reserves for contingencies when the Company believes that it is probable that a loss has been incurred and the amount of loss can be reasonably estimated. The Company discloses a contingency if there is at least a reasonable possibility that a loss may have been incurred and there is no reserve for the loss because the conditions above are not met. The Company's disclosure includes an estimate of the reasonably possible loss or range of loss for those matters, for which an estimate can be made. Neither a reserve nor disclosure is required for losses that are deemed remote . The Company appropriately reserves for certain matters where, in the opinion of management, the likelihood of liability is probable and the extent of such liability is reasonably estimable. Such amounts are included within accounts payable, accrued expenses and other liabilities in the accompanying consolidated statements of financial condition. Estimates, by their nature, are based on judgment and currently available information and involve a variety of factors, including, but not limited to, the type and nature of the litigation, claim or proceeding, the progress of the matter, the advice of legal counsel, the Company's defenses and its experience in similar cases or proceedings as well as its assessment of matters, including settlements, involving other defendants in similar or related cases or proceedings. The Company may increase or decrease its legal reserves in the future, on a matter-by-matter basis, to account for developments in such matters. The Company accrues legal fees as incurred. The following information reflects developments with respect to the Company's legal proceedings that occurred in the quarter ended September 30, 2015. These items should be read together with the Company's discussion in Note 18 "Commitments and Contingencies" in the Notes to Consolidated Financial Statements in Part IV and the Company's discussion set forth under Legal Proceedings in Part I, Item 3 of the Company's Annual Report on Form 10-K for the year ended December 31, 2014. On May 28, 2014, Energy Intelligence Group, Inc. and Energy Intelligence Group UK (collectively, "EIG") filed a lawsuit against Cowen and Company, LLC in the United States Court for the Southern District of New York (Energy Intelligence Group, Inc. and Energy Intelligence Group UK v. Cowen and Company, LLC, No. 14-CV-3789). The complaint alleges copyright infringement based on alleged impermissible distribution of EIG's publication, Oil Daily, by Cowen and Company, LLC, and Dahlman Rose & Company, LLC, as Cowen's alleged predecessor-in-interest. EIG is seeking statutory damages based on alleged willful infringement of their copyrights. The Company intends to vigorously defend against this lawsuit. On November 12, 2014, the Company filed an answer and affirmative defenses to the EIG complaint. During the third quarter, the Company and EIG continued to engage in targeted discovery relating to the Company’s defense that it did not assume unknown liabilities of Dahlman Rose. On September 25, 2015, the Company filed its motion for partial summary judgment to dismiss certain of EIG’s claims relating to Dahlman Rose’s alleged copyright infringement. We expect the Company’s motion to be heard late in the fourth quarter, but we cannot predict when the Court will issue a decision. The case is in its preliminary stages, therefore the Company cannot predict the outcome at this time but does not currently expect this case to have a material effect on its financial position but it could have a material effect on the Company’s results of operations in a future period.

Convertible Debt and Notes Paya

Convertible Debt and Notes Payable	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Convertible Debt and Notes Payable	Convertible Debt and Notes Payable As of September 30, 2015 and December 31, 2014 , the Company's outstanding debt was as follows: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Convertible debt $ 123,149 $ 118,475 Note Payable 63,250 63,250 Other Note payable 355 — Capital lease obligations 3,023 3,894 $ 189,777 $ 185,619 Convertible Debt On March 10, 2014, the Company issued $149.5 million of 3.0% cash convertible senior notes ("Convertible Notes"). The Convertible Notes are due on March 15, 2019 unless earlier repurchased by the Company or converted by the holder into cash in accordance with their terms prior to such date. The interest on the Convertible Notes is payable semi-annually on March 15 and September 15 of each year. The Convertible Notes are senior unsecured obligations and rank senior in right of payments to other obligations. The Convertible Notes may be converted into cash, upon the occurrence of certain events, whereby a holder will receive, per $1,000 principal amount of notes being converted, an amount equal to the sum of principal amount outstanding and the conversion amount based on the current conversion price (the "Conversion Option"). The Convertible Notes were issued with an initial conversion price of $5.33 per share. The Company recorded interest expense of $1.1 million for the three months ended September 30, 2015 and 2014, respectively, and $3.4 million and $1.1 million for the nine months ended September 30, 2015 and 2014 , respectively. The initial unamortized discount on the Convertible Notes was $35.7 million and is shown net in convertible debt in the accompanying consolidated statements of financial condition. Amortization on the discount, included within interest expense in the accompanying consolidated statements of operations is $1.6 million and $1.5 million for the three months ended September 30, 2015 and 2014 and $4.7 million and $3.2 million for the nine months ended September 30, 2015 and 2014 , respectively, based on an effective interest rate of 8.89% . The Company capitalized the debt issuance costs in the amount of $3.7 million , which is included in other assets in the accompanying consolidated statements of financial condition , and will be amortized over the life of the Convertible Notes. As of September 30, 2015 , the Company is in compliance with all covenants included in the indenture governing the Convertible Notes. Of the net proceeds from the sale of the Convertible Notes, approximately $20.5 million was applied to pay the net cost of a cash convertible note economic hedge and warrant transaction which increases the effective conversion price to $7.18 (see Note 5 ), and approximately $0.3 million was applied to repurchase shares of Cowen Class A common stock. The remainder of the net proceeds is being used for general corporate purposes. Note Payable On October 10, 2014 the Company completed its public offering of $63.3 million aggregate principal amount of 8.25% senior notes due on October 15, 2021 ("2021 Notes"). Interest on the 2021 Notes is payable quarterly in arrears on January 15, April 15, July 15 and October 15, commencing on January 15, 2015. The Company recorded interest expense of $1.3 million and $3.9 million for the three and nine months ended September 30, 2015 , respectively. The Company capitalized debt issuance costs of approximately $2.9 million which are included in other assets in the accompanying consolidated statements of financial condition and will be amortized over the life of the 2021 Notes. As of September 30, 2015 , the Company is in compliance with all covenants included in the indenture governing the 2021 Notes. Other Note Payable During January 2015, the Company borrowed $2.0 million to fund insurance premium payments. This note has an effective interest rate of 1.33% and is due on December 1, 2015, with monthly payment requirements of $0.2 million . As of September 30, 2015 , the outstanding balance on this note payable was $0.4 million . Interest expense for the three and nine months ended September 30, 2015 was insignificant. Revolver On July 31, 2015, the Company entered into a $25.0 million 364 day revolving unsecured credit facility with multiple financial institutions. The Company had no amounts outstanding under this facility as of September 30, 2015 . Interest accrues on borrowed funds at LIBOR plus 3.0% and interest accrues on the undrawn facility amount at LIBOR plus 0.38% . The Company is required to comply with certain financial covenants for which the Company was in compliance with at September 30, 2015 . Capital Lease Obligations The Company entered into several capital leases for computer equipment during the fourth quarter of 2010 and one in January 2014. These leases amounted to $7.6 million and are recorded in fixed assets and as capital lease obligations, which are included in short-term borrowings and other debt in the accompanying consolidated statements of financial condition, and have lease terms that range from 48 to 60 months and interest rates that range from 0.60% to 6.03% . As of September 30, 2015 , t he remaining balance on these capital leases was $3.0 million . Interest expense was $0.1 million for the three months ended September 30, 2015 and 2014, respectively, and $0.1 million and $0.2 million for the nine months ended September 30, 2015 and 2014, respectively. Annual scheduled maturities of debt and minimum payments for all debt outstanding as of September 30, 2015 , is as follows: Convertible Debt Note Payable Other Note Payable Capital Lease (dollars in thousands) 2015 $ — $ 1,304 $ 361 $ 330 2016 4,485 5,218 — 1,025 2017 4,485 5,218 — 938 2018 4,485 5,218 — 938 2019 151,743 5,218 — 78 Thereafter — 73,686 — — Subtotal 165,198 95,862 361 3,309 Less: Amount representing interest (a) (42,049 ) (32,612 ) (6 ) (286 ) Total $ 123,149 $ 63,250 $ 355 $ 3,023 (a) Amount necessary to reduce net minimum payments to present value calculated at the Company's implicit rate at inception. This amount also includes the unamortized discount on the convertible debt. Letters of Credit As of September 30, 2015 , the Company has the following seven irrevocable letters of credit related to leased office space, for which there is cash collateral pledged, which the Company pays a fee on the stated amount of the letter of credit. Location Amount Maturity (dollars in thousands) San Francisco $ 710 October 2025 New York $ 1,000 February 2016 Boston $ 382 March 2016 New York $ 355 May 2016 New York $ 1,861 May 2016 New York $ 794 October 2016 New York $ 3,935 October 2016 To the extent any letter of credit is drawn upon, interest will be assessed at the prime commercial lending rate . As of September 30, 2015 and December 31, 2014 , there were no amounts due related to these letters of credit .

Stockholder's Equity

Stockholder's Equity	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Stockholder's Equity	Stockholder's Equity Preferred Stock and Purchase of Capped Call Option On May 19, 2015, the Company completed its offering of 120,750 shares of the Company's 5.625% Series A cumulative perpetual convertible preferred stock ("Series A Convertible Preferred Stock") that provided $117.2 million of proceeds, net of underwriting fees and issuance costs of $3.4 million . Each share of the Series A Convertible Preferred Stock is entitled to dividends at a rate of 5.625% per annum which will be payable, when and if declared by the board of directors of the Company, quarterly, in arrears, on February 15, May 15, August 15 and November 15 of each year. The Company may, at its option, pay dividends in cash, common stock or a combination thereof . During the three and nine months ended September 30, 2015 the Company declared and accrued a cash dividend of $1.6 million and $2.4 million , respectively. Each share of Series A Convertible Preferred Stock is non-voting and will have liquidity preference over the Company's Class A common stock and will rank senior to all classes or series of the Company's Class A common stock, but junior to all of the Company's existing and future indebtedness with respect to divided rights and rights upon the Company's involuntary liquidation, dissolution or winding down. Each share of Series A Convertible Preferred Stock is convertible, at the option of the holder, into a number of shares of our Class A common stock equal to the liquidation preference of $1,000 divided by the conversion rate. The initial conversion rate is 152.2476 shares of the Company's Class A common stock for each share of the Series A Convertible Preferred Stock. At any time on or after May 20, 2020, the Company may elect all outstanding shares of the Series A Convertible Preferred Stock to be automatically converted into shares of the Company’s Class A common stock, cash or a combination thereof, at the Company’s election, in each case, based on the then-applicable conversion rate, if the last reported sale price of the Company’s Class A common stock equals or exceeds 150% of the then-current conversion price on at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days (including on the last trading day of such period) immediately prior to such election. At the time of conversion, the conversion rate may be adjusted based on certain events including but not limited to the issuance of cash dividends or Class A common stock as a dividends to the Company's Class A common shareholders or a share split or combination. In connection with the issuance and sale of the Series A Convertible Preferred Stock, the Company entered into a privately negotiated capped call option transaction (the “Capped Call Option Transaction”) with Nomura Global Financial Products Inc. (the “option counterparty”) for $15.9 million . The Capped Call Option Transaction is expected generally to reduce the potential dilution to the Company’s Class A common stock (had the Company elected to convert to common shares) and/or offset any cash payments that the Company is required to make upon conversion of any Series A Convertible Preferred Stock. The Capped Call Option Transaction has an initial effective strike price of $6.57 per share, which matches the initial conversion price of the Series A Convertible Preferred Stock, and a cap price of $8.39 per share. However, to the extent that the market price of Class A common stock, as measured under the terms of the Capped Call Option Transaction, exceeds the cap price thereof, there would nevertheless be dilution and/or such cash payments would not be offset. As the Capped Call Option Transaction is a free standing derivative that is indexed to the Company's own stock price and the Company controls if it is settled in cash or stock it qualifies for equity classification as a reduction to additional paid in capital. Treasury Stock Treasury stock of $130.0 million as of September 30, 2015 , compared to $79.8 million as of December 31, 2014 , resulted from $8.6 million acquired through repurchases of shares to cover employee minimum tax withholding obligations related to stock compensation vesting events under the Company's Equity Plan or other similar transactions and $41.7 million purchased in connection with a share repurchase program. The following represents the activity relating to the treasury stock held by the Company during the nine months ended September 30, 2015 : Treasury stock shares Cost Average cost Balance outstanding at December 31, 2014 23,507,656 $ 79,771 $ 3.39 Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions 1,574,949 8,556 5.43 Treasury stock reissued — — — Purchase of treasury stock 7,694,214 41,697 5.42 Balance outstanding at September 30, 2015 32,776,819 $ 130,024 $ 3.97

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss) (Notes)	9 Months Ended
	Sep. 30, 2015
Accumulated Other Comprehensive Income / (Loss) [Abstract]
Accumulated other comprehensive income (loss)	Accumulated Other Comprehensive Income (Loss) Accumulated other comprehensive income includes the after tax change in unrealized gains and losses on foreign currency translation adjustments and net gain (loss) and amortization of prior service costs related to the Company's defined benefit plans. Foreign currency translation (a) Defined benefit plans (a) Total (dollars in thousands) Balance at December 31, 2014 $ 17 $ — $ 17 Net change (4 ) — (4 ) Balance at September 30, 2015 $ 13 $ — $ 13 Foreign currency translation (a) Defined benefit plans (a) Total (dollars in thousands) Balance at December 31, 2013 $ 248 $ 344 $ 592 Net change (233 ) (87 ) (320 ) Balance at September 30, 2014 $ 15 $ 257 $ 272 (a) During the periods presented, the Company did not have material reclassifications out of other comprehensive income.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The Company calculates its basic and diluted earnings per share in accordance with US GAAP. Basic earnings per share is calculated by dividing net income attributable to the Company's common stockholders by the weighted average number of common shares outstanding for the period. As of September 30, 2015 , there were 107,098,068 shares outstanding. The Company has included 497,570 fully vested, unissued restricted stock units in its calculation of basic earnings per share. Diluted earnings per common share are calculated by adjusting the weighted average outstanding shares to assume conversion of all potentially dilutive items. The Company uses the treasury stock method to reflect the potential dilutive effect of the warrants (see Note 5 (a)), unexercised stock options, unvested restricted shares, restricted stock units, and SAR's. In calculating the number of dilutive shares outstanding, the shares of common stock underlying unvested restricted shares and restricted stock units are assumed to have been delivered, and options and warrants are assumed to have been exercised, on the grant date. The assumed proceeds from the assumed vesting, delivery and exercising were calculated as the sum of (a) the amount of compensation cost attributed to future services and not yet recognized and (b) the amount of tax benefit that would be credited to additional paid-in capital assuming vesting and delivery of the shares. The tax benefit is the amount resulting from a tax deduction for compensation in excess of compensation expense recognized for financial statement reporting purposes. All outstanding warrants were not included in the computation of diluted net income (loss) per common share for the three and nine months ended September 30, 2015 and 2014, respectively, as their inclusion would have been anti-dilutive. The Company can elect to settle the Series A Convertible Preferred Stock in shares or cash. The Company's intent is to settle in cash and, based on current and projected liquidity needs, the Company has the ability to do so. The computation of earnings per share is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (dollars in thousands, except per share data) Net income (loss) $ (6,002 ) $ 10,529 $ 24,048 $ 38,154 Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds 4,344 4,006 10,980 13,409 Net income (loss) attributable to Cowen Group, Inc. (10,346 ) 6,523 13,068 24,745 Preferred stock dividends 1,603 — 2,358 — Net income (loss) attributable to Cowen Group, Inc. common stockholders $ (11,949 ) $ 6,523 $ 10,710 $ 24,745 Shares for basic and diluted calculations: Weighted average shares used in basic computation 109,191 114,969 111,050 115,407 Stock options — — 19 — Performance based restricted stock — — 266 — Stock appreciation rights — 59 152 57 Restricted stock — 3,773 5,762 4,563 Weighted average shares used in diluted computation 109,191 118,801 117,249 120,027 Earnings (loss) per share: Basic $ (0.11 ) $ 0.06 $ 0.10 $ 0.21 Diluted $ (0.11 ) $ 0.05 $ 0.09 $ 0.21

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company conducts its operations through two segments: the alternative investment segment and the broker‑dealer segment. These activities are conducted primarily in the United States and substantially all of its revenues are generated domestically. The performance measure for these segments is Economic Income (Loss), which management uses to evaluate the financial performance of and make operating decisions for the segments including determining appropriate compensation levels. Expenses not directly associated with specific segments are allocated based on the most relevant measures applicable, including headcount, square footage and other factors. In general, Economic Income (Loss) is a pre-tax measure that (i) eliminates the impact of consolidation for consolidated funds (ii) excludes goodwill and intangible impairment (iii) excludes certain other acquisition-related and/or reorganization expenses and (iv) excludes preferred stock dividends. In addition, Economic Income (Loss) revenues include investment income that represents the income the Company has earned in investing its own capital, including realized and unrealized gains and losses, interest and dividends, net of associated investment related expenses. For US GAAP purposes, these items are included in each of their respective line items. Economic Income (Loss) revenues also include management fees, incentive income and investment income earned through the Company's investment as a general partner in certain real estate entities and the Company's investment in the activist business. For US GAAP purposes, all of these items are recorded in other income (loss). In addition, Economic Income (Loss) expenses are reduced by reimbursement from affiliates, which for US GAAP purposes is presented gross as part of revenue. As further stated below, one major difference between Economic Income (Loss) and US GAAP net income (loss) is that Economic Income (Loss) presents the segments' results of operations without the impact resulting from the full consolidation of any of the Consolidated Funds. Consolidation of these funds results in including in income the pro rata share of the income or loss attributable to other owners of such entities which is reflected in net income (loss) attributable to redeemable non-controlling interest in consolidated subsidiaries in the accompanying consolidated statements of operations. This pro rata share has no effect on the overall financial performance for the alternative investment segment, as ultimately, this income or loss is not income or loss for the alternative investment segment itself. Included in Economic Income (Loss) is the actual pro rata share of the income or loss attributable to the Company as an investor in such entities, which is relevant in management making operating decisions and evaluating financial performance. The following tables set forth operating results for the Company's alternative investment and broker dealer segments and related adjustments necessary to reconcile the Company's Economic Income (Loss) measure to arrive at the Company's consolidated US GAAP net income (loss): Three Months Ended September 30, 2015 Adjustments Alternative Broker-Dealer Total Economic Income/(Loss) Funds Other US GAAP (dollars in thousands) Revenues Investment banking $ — $ 53,012 $ 53,012 $ — $ — $ 53,012 Brokerage 18 41,857 41,875 — (790 ) (e) 41,085 Management fees 17,739 282 18,021 (371 ) (7,131 ) (a) 10,519 Incentive income (8,629 ) — (8,629 ) 29 8,693 (a) 93 Investment Income (16,781 ) (5,243 ) (22,024 ) — 22,024 (c) — Interest and dividends — — — — 3,604 (c)(e) 3,604 Reimbursement from affiliates — — — (85 ) 3,440 (f) 3,355 Other revenue (9 ) 573 564 — 748 (c) 1,312 Consolidated Funds revenues — — — 274 — 274 Total revenues (7,662 ) 90,481 82,819 (153 ) 30,588 113,254 Expenses Non interest expense 6,133 84,721 90,854 — 2,112 (c)(d) 92,966 Interest and dividends 2,970 1,287 4,257 — 3,110 (c)(e) 7,367 Consolidated Funds expenses — — — 634 — 634 Total expenses 9,103 86,008 95,111 634 5,222 100,967 Total other income (loss) — — — 554 (23,924 ) (c) (23,370 ) Income taxes expense / (benefit) — — — — (5,081 ) (b) (5,081 ) (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (2,231 ) — (2,231 ) 233 (2,346 ) (4,344 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ (18,996 ) $ 4,473 $ (14,523 ) $ — $ 4,177 $ (10,346 ) Three Months Ended September 30, 2014 Adjustments Alternative Broker-Dealer Total Funds Other US GAAP (dollars in thousands) Revenues Investment banking $ — $ 45,799 $ 45,799 $ — $ — $ 45,799 Brokerage 15 35,568 35,583 — (1,249 ) (e) 34,334 Management fees 16,319 — 16,319 (246 ) (6,277 ) (a) 9,796 Incentive income 4,488 — 4,488 (34 ) (5,291 ) (a) (837 ) Investment Income 4,064 3,399 7,463 — (7,463 ) (c) — Interest and dividends — — — — 13,725 (c)(e) 13,725 Reimbursement from affiliates — — — 119 2,354 (f) 2,473 Other revenue 43 353 396 — 724 (c) 1,120 Consolidated Funds revenues — — — 691 — 691 Total revenues 24,929 85,119 110,048 530 (3,477 ) 107,101 Expenses Non interest expense 21,754 77,050 98,804 — 832 (c)(d) 99,636 Interest and dividends 1,852 812 2,664 — 9,765 (c)(e) 12,429 Consolidated Funds expenses — — — 635 — 635 Total expenses 23,606 77,862 101,468 635 10,597 112,700 Total other income (loss) — — — 888 15,381 (c) 16,269 Income taxes expense / (benefit) — — — — 141 (b) 141 (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (1,877 ) — (1,877 ) (783 ) (1,346 ) (4,006 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ (554 ) $ 7,257 $ 6,703 $ — $ (180 ) $ 6,523 Nine Months Ended September 30, 2015 Adjustments Alternative Investment Broker-Dealer Total Economic Income/(Loss) Funds Consolidation Other Adjustments US GAAP (dollars in thousands) Revenues Investment banking $ — $ 186,763 $ 186,763 $ — $ — $ 186,763 Brokerage 41 112,292 112,333 — (837 ) (e) 111,496 Management fees 50,885 282 51,167 (937 ) (19,061 ) (a) 31,169 Incentive income (1,081 ) — (1,081 ) (278 ) 1,724 (a) 365 Investment Income 14,309 4,763 19,072 — (19,072 ) (c) — Interest and dividends — — — — 9,846 (c)(e) 9,846 Reimbursement from affiliates — — — (261 ) 10,760 (f) 10,499 Other revenue 84 605 689 — 1,995 (c) 2,684 Consolidated Funds revenues — — — 1,134 — 1,134 Total revenues 64,238 304,705 368,943 (342 ) (14,645 ) 353,956 Expenses Non interest expense 57,164 273,939 331,103 — 4,799 (c)(d) 335,902 Interest and dividends 8,880 3,545 12,425 — 6,816 (c)(e) 19,241 Consolidated Funds expenses — — — 1,626 — 1,626 Total expenses 66,044 277,484 343,528 1,626 11,615 356,769 Total other income (loss) — — — 4,278 27,795 (c) 32,073 Income taxes expense / (benefit) — — — — 5,212 (b) 5,212 (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (6,128 ) — (6,128 ) (2,310 ) (2,542 ) (10,980 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ (7,934 ) $ 27,221 $ 19,287 $ — $ (6,219 ) $ 13,068 Nine Months Ended September 30, 2014 Adjustments Alternative Investment Broker-Dealer Total Economic Income/(Loss) Funds Consolidation Other Adjustments US GAAP (dollars in thousands) Revenues Investment banking $ — $ 125,653 $ 125,653 $ — $ — $ 125,653 Brokerage 40 104,943 104,983 — (4,508 ) (e) 100,475 Management fees 46,574 — 46,574 (723 ) (17,439 ) (a) 28,412 Incentive income 16,900 — 16,900 (188 ) (12,327 ) (a) 4,385 Investment Income 29,025 8,207 37,232 — (37,232 ) (c) — Interest and dividends — — — — 35,437 (c)(e) 35,437 Reimbursement from affiliates — — — (45 ) 7,436 (f) 7,391 Other revenue 140 354 494 — 1,933 (c) 2,427 Consolidated Funds revenues — — — 2,500 — 2,500 Total revenues 92,679 239,157 331,836 1,544 (26,700 ) 306,680 Expenses Non interest expense 71,421 220,913 292,334 — 3,269 (c)(d) 295,603 Interest and dividends 5,083 878 5,961 — 23,733 (c)(e) 29,694 Consolidated Funds expenses — — — 1,335 — 1,335 Total expenses 76,504 221,791 298,295 1,335 27,002 326,632 Total other income (loss) — — — 3,509 54,863 (c) 58,372 Income taxes expense / (benefit) — — — — 266 (b) 266 (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (8,320 ) — (8,320 ) (3,718 ) (1,371 ) (13,409 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ 7,855 $ 17,366 $ 25,221 $ — $ (476 ) $ 24,745 The following is a summary of the adjustments made to US GAAP net income (loss) for the segment to arrive at Economic Income (Loss): Funds Consolidation: The impacts of consolidation and the related elimination entries of the Consolidated Funds are not included in Economic Income (Loss). Adjustments to reconcile to US GAAP net income (loss) include elimination of incentive income and management fees earned from the Consolidated Funds and addition of fund expenses excluding management fees paid, fund revenues and investment income (loss). Other Adjustments: (a) Economic Income (Loss) recognizes revenues (i) net of distribution fees paid to agents and (ii) our proportionate share of management and incentive fees of certain real estate operating entities and the activist business. (b) Economic Income (Loss) excludes income taxes as management does not consider this item when evaluating the performance of the segment. (c) Economic Income (Loss) recognizes Company income from proprietary trading (including interest and dividends) net of related expenses. (d) Economic Income (Loss) recognizes the Company's proportionate share of expenses for certain real estate and other operating entities for which the investments are recorded under the equity method of accounting for investments. (e) Economic Income (Loss) recognizes stock borrow/loan activity (prior to January 2015) and other brokerage dividends as brokerage revenue. (f) Reimbursement from affiliates is shown as a reduction of Economic Income expenses, but is included as a part of revenues under US GAAP. For the three and nine months ended September 30, 2015 and 2014, there was no one fund or other customer which represented more than 10% of the Company's total revenues.

Regulatory Requirements

Regulatory Requirements	9 Months Ended
	Sep. 30, 2015
Brokers and Dealers [Abstract]
Regulatory Requirements	Regulatory Requirements As registered broker-dealers, Cowen and Company, ATM Execution and Cowen Prime are subject to the SEC's Uniform Net Capital Rule 15c3-1 (the “Rule”), which requires the maintenance of minimum net capital. Under the alternative method permitted by the Rule, Cowen and Company's minimum net capital requirement, as defined, is $1.0 million . Under the alternative method ATM Execution and Cowen Prime are required to maintain minimum net capital, as defined, equal to $250,000 . The broker-dealers are not permitted to withdraw equity if certain minimum net capital requirements are not met. As of September 30, 2015 , Cowen and Company had total net capital of approximately $123.4 million , which was approximately $122.4 million in excess of its minimum net capital requirement of $1.0 million . As of September 30, 2015 , ATM Execution had total net capital of approximately $4.7 million , which was approximately $4.4 million in excess of its minimum net capital requirement of $250,000 . As of September 30, 2015 , Cowen Prime had total net capital of approximately $4.2 million , which was approximately $3.9 million in excess of its minimum net capital requirement of $250,000 . Cowen and Company, ATM Execution and Cowen Prime claim exemption from the provisions of Rule 15c3-3 under the Securities Exchange Act of 1934 as their activities are limited to those set forth in the conditions for exemption appearing in paragraph (k)(2)(ii) of the Rule. Proprietary accounts of broker dealers (“PAB”) held at the clearing broker are considered allowable assets for net capital purposes, pursuant to agreements between Cowen and Company and ATM Execution and the clearing broker, which require, among other things, that the clearing broker performs computations for PAB and segregates certain balances on behalf of Cowen and Company, ATM Execution and Cowen Prime, if applicable. Ramius UK Ltd. ("Ramius UK") and Cowen International Limited ("CIL") are subject to the capital requirements of the Financial Conduct Authority (“FCA”) of the UK. Financial Resources, as defined, must exceed the requirement of the FCA . As of September 30, 2015 , Ramius UK's Financial Resources of $0.29 million exceeded its minimum requirement of $0.06 million by $0.2 million . As of September 30, 2015 , CIL's Financial Resources of $3.3 million exceeded its minimum requirement of $2.0 million by $1.3 million . Cowen and Company (Asia) Limited (“Cowen Asia”) is subject to the financial resources requirements of the Securities and Futures Commission (“SFC”) of Hong Kong. Financial Resources, as defined, must exceed the Total Financial Resources requirement of the SFC. As of September 30, 2015 , Cowen Asia's Financial Resources of $0.5 million exceeded the minimum requirement of $0.4 million by $0.1 million .

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company and its affiliated entities are the managing member, general partner and/or investment manager to the Company's alternative asset management products and certain managed accounts. Management fees and incentive income are primarily earned from affiliated entities. As of September 30, 2015 and December 31, 2014 , $5.4 million and $5.1 million , respectively, included in fees receivable are earned from related parties. The Company may, at its discretion, reimburse certain fees charged to the funds that it manages to avoid duplication of fees when such funds have an underlying investment in another affiliated investment fund. The Company reimbursed the funds it manages an immaterial amount for the three months ended September 30, 2015 and 2014 and for the nine months ended September 30, 2015. For the nine months ended September 30, 2014, the Company reimbursed the funds it manages $0.8 million , which were recorded net in management fees and incentive income in the accompanying consolidated statements of operations. As of September 30, 2015 and December 31, 2014 , related amounts still payable were $0.1 million and $0.1 million , respectively, and were reflected in fees payable in the accompanying consolidated statements of financial condition. Fees receivable and fees payable are recorded at carrying value, which approximates fair value. The Company may also make loans to employees or other affiliates, excluding executive officers of the Company. These loans are interest bearing and settle pursuant to the agreed-upon terms with such employees or affiliates and are included in due from related parties in the accompanying consolidated statements of financial condition. As of September 30, 2015 and December 31, 2014 , loans to employees of $3.8 million and $6.1 million , respectively, were included in due from related parties on the accompanying consolidated statements of financial condition. Of these amounts $1.7 million and $3.9 million , respectively, are related to forgivable loans. These forgivable loans provide for a cash payment up-front to employees, with the amount due back to the Company forgiven over a vesting period. An employee that voluntarily ceases employment, or is terminated with cause, is generally required to pay back to the Company any unvested forgivable loans granted to them. The forgivable loans are recorded as an asset to the Company on the date of grant and payment, and then amortized to compensation expense on a straight-line basis over the vesting period. The vesting period on forgivable loans is generally one to three years. The Company recorded compensation expense of $0.6 million and $1.3 million , for the three months ended September 30, 2015 and 2014 and $2.6 million and $3.2 million for the nine months ended September 30, 2015 and 2014 , respectively. This expense is included in employee compensation and benefits in the accompanying consolidated statement of operations. For the three and nine months ended September 30, 2015 , and 2014 , the interest income was insignificant for all loans and advances. The remaining balance included in due from related parties primarily relates to amounts due to the Company from affiliated funds and real estate entities due to expenses paid on their behalf. Included in due to related parties is approximately $0.3 million and $0.5 million as of September 30, 2015 and December 31, 2014 , respectively, related to a subordination agreement with an investor in certain real estate funds. This total is based on a hypothetical liquidation of the real estate funds as of the balance sheet date. During March 2015, the Company issued a $15.0 million unsecured loan to its real estate business with maturity of June 29, 2015 and an effective annualized interest rate of 8.8% . This balance was fully repaid to the Company during June 2015. The interest income for the three and nine months ended September 30, 2015 was $0.3 million . During June 2015, the Company issued a $0.9 million unsecured loan to its real estate business with a maturity date of July 29, 2015 and an effective annualized interest rate of LIBOR plus 6% . This loan is included in due from related parties on the accompanying consolidated statements of financial condition. The interest income for the three and nine months ended September 30, 2015 was insignificant. Employees and certain other related parties invest on a discretionary basis within consolidated entities. These investments generally are subject to preferential management fee and performance fee arrangements. As of September 30, 2015 and December 31, 2014 , such investments aggregated $ 25 million and $ 15 million , respectively, were included in redeemable non-controlling interests on the accompanying consolidated statements of financial condition. Their share of the net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds aggregated $ 5.5 million and $ 3.2 million for the three months ended September 30, 2015 and 2014 and $ 10.3 million and $ 10.1 million for the nine months ended September 30, 2015 and 2014 , respectively.

Guarantees and Off-Balance Shee

Guarantees and Off-Balance Sheet Arrangements	9 Months Ended
	Sep. 30, 2015
Guarantees and Off Balance Sheet Arrangements [Abstract]
Guarantees and Off-Balance Sheet Arrangements	Guarantees and Off-Balance Sheet Arrangements Guarantees US GAAP requires the Company to disclose information about its obligations under certain guarantee arrangements. Those standards define guarantees as contracts and indemnification agreements that contingently require a guarantor to make payments to the guaranteed party based on changes in an underlying security (such as an interest or foreign exchange rate, security or commodity price, an index or the occurrence or nonoccurrence of a specified event) related to an asset, liability or equity security of a guaranteed party. Those standards also define guarantees as contracts that contingently require the guarantor to make payments to the guaranteed party based on another entity's failure to perform under an agreement as well as indirect guarantees of the indebtedness of others. In the normal course of its operations, the Company enters into contracts that contain a variety of representations and warranties and which provide general indemnifications. The Company's maximum exposure under these arrangements is unknown as this would involve future claims that may be made against the Company that have not yet occurred. However, based on experience, the Company expects the risk of loss to be remote. The Company indemnifies and guarantees certain service providers, such as clearing and custody agents, trustees and administrators, against specified potential losses in connection with their acting as an agent of, or providing services to, the Company or its affiliates. The Company also indemnifies some clients against potential losses incurred in the event specified third-party service providers, including sub-custodians and third-party brokers, improperly execute transactions. The maximum potential amount of future payments that the Company could be required to make under these indemnifications cannot be estimated. However, the Company believes that it is unlikely it will have to make significant payments under these arrangements and has not recorded any contingent liability in the consolidated financial statements for these indemnifications. The Company is a member of various securities exchanges. Under the standard membership agreements, members are required to guarantee the performance of other members and, accordingly, if another member becomes unable to satisfy its obligations to the exchange, all other members would be required to meet the shortfall. The Company's liability under these arrangements is not quantifiable and could exceed the cash and securities it has posted as collateral. However, management believes that the potential for the Company to be required to make payments under these arrangements is remote. Accordingly, no contingent liability is recorded in the accompanying consolidated statements of financial condition for these arrangements. The Company also provides representations and warranties to counterparties in connection with a variety of commercial transactions and occasionally indemnifies them against potential losses caused by the breach of those representations and warranties. The Company may also provide standard indemnifications to some counterparties to protect them in the event additional taxes are owed or payments are withheld, due either to a change in or adverse application of certain tax laws. These indemnifications generally are standard contractual terms and are entered into in the normal course of business. The maximum potential amount of future payments that the Company could be required to make under these indemnifications cannot be estimated. However, the Company believes it is unlikely it will have to make material payments under these arrangements and has not recorded any contingent liability in the accompanying consolidated financial statements for these indemnifications. Off-Balance Sheet Arrangements The Company has no material off-balance sheet arrangements as of September 30, 2015 and December 31, 2014. However, through indemnification provisions in the clearing agreement, customer activities may expose the Company to off-balance-sheet credit risk. Pursuant to the clearing agreement, the Company is required to reimburse the Company's clearing broker, without limit, for any losses incurred due to a counterparty's failure to satisfy its contractual obligations. However, these transactions are collateralized by the underlying security, thereby reducing the associated risk to changes in the market value of the security through the settlement date. In addition, during the normal course of business, the Company has exposure to a number of risks including market risk, currency risk, credit risk, operational risk, liquidity risk and legal risk. As part of the Company's risk management process, these risks are monitored on a regular basis throughout the course of the year.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 1, 2015, the Company completed its acquisition of all of the outstanding interests in Conifer Securities, LLC ("Conifer"), a registered broker-dealer (member FINRA and SIPC) representing the prime brokerage services division of Conifer Financial Services LLC. The acquisition was completed for a combination of cash and contingent consideration. In accordance with the terms of the purchase agreement, the Company is required to pay the sellers a portion of future net revenues once certain revenue targets are achieved through December 31, 2018. The Company is currently in the process of identifying the assets and liabilities acquired and finalizing the purchase price and valuation for certain acquired assets of Conifer therefore the initial accounting for the business acquisition is incomplete. Following the acquisition, Conifer was in the process of being integrated in to the broker-dealer segment and was renamed Cowen Prime Services Trading, LLC. On October 28, 2015, the Company's Board of Directors approved a $19.1 million increase in the Company's share repurchase program (see Note 15 ) bringing the total remaining shares available for repurchase to $25.0 million . The Company has evaluated events that have occurred after the balance sheet date but before the financial statements are issued and has determined that there were no additional subsequent events requiring adjustment or disclosure in the consolidated financial statements.

Significant Accounting Polici30

Significant Accounting Policies - Quarterly (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of presentation	Basis of Presentation These unaudited condensed consolidated financial statements and related notes have been prepared in accordance with US GAAP and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) related to interim financial statements. Results for interim periods should not be considered indicative of results for any other interim period or for the full year. These financial statements should be read in conjunction with the audited consolidated financial statements as of December 31, 2014 and 2013 and for the years ended December 31, 2014, 2013, and 2012, included in the Form 10-K of Cowen Group as filed with the SEC on February 26, 2015 and amended on March 30, 2015. The financial information contained herein is unaudited; however, management believes all adjustments have been made that are necessary for a fair presentation of the results for the interim periods. The year-end balance sheet data was derived from audited financial statements, but does not include all disclosures required by US GAAP. These condensed consolidated financial statements include the accounts of the Company, its operating and other subsidiaries, and entities in which the Company has a controlling financial interest or a substantive controlling general partner interest. All material intercompany transactions and balances have been eliminated in consolidation. Certain fund entities that are consolidated in these condensed consolidated financial statements, as further discussed below, are not subject to these consolidation provisions with respect to their own investments pursuant to their specialized accounting. The Company serves as the managing member/general partner and/or investment manager to affiliated fund entities which it sponsors and manages. Funds in which the Company has a controlling financial interest are consolidated with the Company pursuant to US GAAP as described below. Consequently, the Company's condensed consolidated financial statements reflect the assets, liabilities, income and expenses of these funds on a gross basis. The ownership interests in these funds that are not owned by the Company are reflected as redeemable non-controlling interests in consolidated subsidiaries in the accompanying condensed consolidated financial statements. The management fees and incentive income earned by the Company from these funds are eliminated in consolidation.
Principles of consolidation	Principles of consolidation The Company determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting operating entity ("VOE") or a variable interest entity ("VIE") under US GAAP. Voting Operating Entities — VOEs are entities in which (i) the total equity investment at risk is sufficient to enable the entity to finance its activities independently and (ii) the equity holders at risk have the obligation to absorb losses, the right to receive residual returns and the right to direct the activities of the entity that most significantly impact the entity's economic performance. Under US GAAP, the usual condition for a controlling financial interest in a VOE is ownership of a majority voting interest. Accordingly, the Company consolidates VOEs in which it owns a majority of the entity's voting shares or units. US GAAP also provides that a general partner of a limited partnership (or a managing member, in the case of a limited liability company) is presumed to control the partnership, and thus should consolidate it, unless a simple majority of the limited partners has the right to remove the general partner without cause or to terminate the partnership. In accordance with these standards, the Company presently consolidates three entities deemed to be VOEs for which it acts as the general partner and investment manager. As of September 30, 2015 and December 31, 2014 and during the three and nine month periods ended September 30, 2015 and 2014 , the Company consolidated the following funds: Ramius Enterprise LP (“Enterprise LP”) and Ramius Merger Fund LLC (the "Merger Fund") and as of May 1, 2015, the date that the entity began operations, the Company also consolidates Quadratic Fund LLC ("Quadratic LLC") (collectively the "Consolidated Funds") . RCG Linkem II LLC, an investment company, is consolidated during the period ending September 30, 2015 . It was formed to make an investment in a wireless broadband communication provider in Italy. Cowen AV Investment LLC, an investment company, was consolidated up through the first quarter of 2015 when it was liquidated. It was formed to make an investment in a biotechnology company focused on developing gene therapies for certain medical needs. Ramius Co-Investment I LLC and Ramius Co-Investment II LLC, both investment companies, were formed to invest in biomedical companies that develop gene therapies for severe genetic disorders. Ramius Co-Investment I LLC was consolidated as of December 31, 2013 but was deconsolidated during the first quarter of 2014 when it was liquidated. Ramius Co-Investment II LLC was consolidated but was liquidated during the quarter ended September 30, 2014. The Company determined that all four investment companies are (or were) VOE's due to the Company's controlling equity interests held through the managing member and/or affiliates and control exercised by the managing member who is not subject to substantive removal rights. Variable Interest Entities— VIEs are entities that lack one or more of the characteristics of a VOE. In accordance with US GAAP, an enterprise must consolidate all VIEs of which it is the primary beneficiary. Under the US GAAP consolidation model for VIEs, an enterprise that (1) has the power to direct the activities of a VIE that most significantly impacts the VIE's economic performance, and (2) has an obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE, is considered to be the primary beneficiary of the VIE and thus is required to consolidate it. However, the Financial Accounting Standards Board ("FASB") has deferred the application of the revised consolidation model for VIEs that meet the following conditions (see "recently issued accounting pronouncements"): (a) the entity has all the attributes of an investment company as defined under AICPA Audit and Accounting Guide, Investment Companies, or does not have all the attributes of an investment company but is an entity for which it is acceptable based on industry practice to apply measurement principles that are consistent with investment companies, (b) the reporting entity does not have explicit or implicit obligations to fund any losses of the entity that could potentially be significant to the entity, and (c) the entity is not a securitization entity, asset-backed financing entity or an entity that was formerly considered a qualifying special-purpose entity. The Company's involvement with its funds is such that all three of the above conditions are met for substantially all of the funds managed by the Company. Where the VIEs have qualified for the deferral, the analysis is based on previous consolidation rules. These rules require an analysis to (a) determine whether an entity in which the Company holds a variable interest is a variable interest entity and (b) whether the Company's involvement, through holding interests directly or indirectly in the entity or contractually through other variable interests (e.g., management and performance related fees), would be expected to absorb a majority of the VIE's expected losses, receive a majority of the VIEs expected residual returns, or both. If these conditions are met, the Company is considered to be the primary beneficiary of the VIE and thus is required to consolidate it. The Company reconsiders whether it is the primary beneficiary of a VIE by performing a periodic qualitative and/or quantitative analysis of the VIE that includes a review of, among other things, its capital structure, contractual agreements between the Company and the VIE, the economic interests that create or absorb variability, related party relationships and the design of the VIE. As of September 30, 2015 and December 31, 2014 , the Company consolidated three and two VIEs, respectively. As of September 30, 2015 and December 31, 2014 , the total net assets of the consolidated VIEs were $1.0 million and $2.0 million , respectively. The VIEs act as managing members/general partners and/or investment managers to affiliated fund entities which they sponsor and/or manage. The VIEs are financed through their operations and/or loan agreements with the Company. As of September 30, 2015 and December 31, 2014 , the Company holds variable interests in Ramius Enterprise Master Fund Ltd (“Enterprise Master”), Ramius Merger Master Fund Ltd ("Merger Master"), as of May 1, 2015, Quadratic Master Fund LTD (Quadratic Master Fund") and, as of September 1, 2015, Cowen Private Investments LP (collectively the “Unconsolidated Master Funds”) through the Consolidated Funds. Investment companies, which account for their investments under the specialized industry accounting guidance for investment companies prescribed under US GAAP, are not subject to the consolidation provisions for their investments. Therefore, the Company has not consolidated the Unconsolidated Master Funds. In the ordinary course of business, the Company also sponsors various other entities that it has determined to be VIEs. These VIEs are primarily funds and real estate entities for which the Company serves as the general partner, managing member and/or investment manager with decision-making rights. The Company does not consolidate any of these funds or real estate entities that are VIEs as it has concluded that it is not the primary beneficiary in each instance. Fund investors are entitled to all of the economics of these VIEs with the exception of the management fee and incentive income, if any, earned by the Company. The Company's involvement with funds and real estate entities that are unconsolidated VIEs is limited to providing investment management services in exchange for management fees and incentive income. Although the Company may advance amounts and pay certain expenses on behalf of the funds and real estate entities that it considers to be VIEs, it does not provide, nor is it required to provide, any type of substantive financial support to these entities outside of regular investment management services (see Note 5 for additional disclosures on VIEs). Equity Method Investments — For operating entities over which the Company exercises significant influence but which do not meet the requirements for consolidation as outlined above, the Company uses the equity method of accounting. The Company's investments in equity method investees are recorded in other investments in the accompanying consolidated statements of financial condition. The Company's share of earnings or losses from equity method investees is included in net gains (losses) on securities, derivatives and other investments in the accompanying consolidated statements of operations. The Company evaluates for impairment its equity method investments whenever events or changes in circumstances indicate that the carrying amounts of such investments may not be recoverable. The difference between the carrying value of the equity method investment and its estimated fair value is recognized as an impairment charge when the loss in value is deemed other than temporary. Other — If the Company does not consolidate an entity, apply the equity method of accounting or account for an investment under the cost method, the Company accounts for such entities (primarily, all securities of such entity which are bought and held principally for the purpose of selling them in the near term as trading securities) in accordance with US GAAP, at fair value with unrealized gains (losses) resulting from changes in fair value reflected within net gains (losses) on securities, derivatives and other investments in the accompanying consolidated statements of operations. Retention of Specialized Accounting — The Consolidated Funds are investment companies and apply specialized industry accounting for investment companies. The Company has retained this specialized accounting for these funds pursuant to US GAAP. The Company reports its investments on the consolidated statements of financial condition at their estimated fair value, with unrealized gains (losses) resulting from changes in fair value reflected within net realized and unrealized gains (losses) on investments and other transactions. Accordingly, the accompanying condensed consolidated financial statements reflect different accounting policies for investments depending on whether or not they are held through a consolidated investment company. In addition, the Company's broker-dealer subsidiaries, Cowen and Company, ATM Execution LLC ("ATM Execution"), Cowen Prime, ATM USA, LLC ("ATM USA") (liquidated during the first quarter of 2015) and Cowen Equity Finance LP ("Cowen Equity Finance") (liquidated during the first quarter of 2015), apply the specialized industry accounting for brokers and dealers in securities also prescribed under US GAAP. The Company also retains specialized accounting in consolidation.
Use of estimates	Use of estimates The preparation of the accompanying condensed consolidated financial statements in conformity with US GAAP requires the management of the Company to make estimates and assumptions that affect the fair value of securities and other investments, the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the accompanying condensed consolidated financial statements, the accounting for goodwill and identifiable intangible assets and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates.
Valuation of investments and derivative contracts	Valuation of investments and derivative contracts US GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurements) and the lowest priority to unobservable inputs (level 3 measurements). The three levels of the fair value hierarchy are as follows: Level 1 Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date; Level 2 Inputs other than quoted prices that are observable for the asset or liability either directly or indirectly, including inputs in markets that are not considered to be active; and Level 3 Fair value is determined based on pricing inputs that are unobservable and includes situations where there is little, if any, market activity for the asset or liability. The determination of fair value for assets and liabilities in this category requires significant management judgment or estimation. Inputs are used in applying the various valuation techniques and broadly refer to the assumptions that market participants use to make valuation decisions, including assumptions about risk. Inputs may include price information, volatility statistics, specific and broad credit data, liquidity statistics, and other factors. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. However, the determination of what constitutes “observable” requires significant judgment by the Company. The Company considers observable data to be that market data which is readily available, regularly distributed or updated, reliable and verifiable, not proprietary, and provided by independent sources that are actively involved in the relevant market. The categorization of a financial instrument within the hierarchy is based upon the pricing transparency of the instrument and does not necessarily correspond to the Company's perceived risk of that instrument. The Company and its operating subsidiaries act as the manager for the Consolidated Funds. Both the Company and the Consolidated Funds hold certain investments which are valued by the Company, acting as the investment manager. The fair value of these investments is generally estimated based on proprietary models developed by the Company, which include discounted cash flow analysis, public market comparables, and other techniques and may be based, at least in part, on independently sourced market information. The material estimates and assumptions used in these models include the timing and expected amount of cash flows, the appropriateness of discount rates used, and, in some cases, the ability to execute, timing of, and estimated proceeds from expected financings. Significant judgment and estimation goes into the selection of an appropriate valuation methodology as well as the assumptions used in these models, and the timing and actual values realized with respect to investments could be materially different from values derived based on the use of those estimates. The valuation methodologies applied impact the reported value of the Company's investments and the investments held by the Consolidated Funds in the condensed consolidated financial statements. Certain of the Company's investments are relatively illiquid or thinly traded and may not be immediately liquidated on demand if needed. Fair values assigned to these investments may differ significantly from the fair values that would have been used had a ready market for the investments existed and such differences could be material . The Company primarily uses the “market approach” to value its financial instruments measured at fair value. In determining an instrument's level within the hierarchy, the Company categorizes the Company's financial instruments into three categories: securities, derivative contracts and other investments. To the extent applicable, each of these categories can further be divided between those held long or sold short. The Company has the option to measure certain financial assets and financial liabilities at fair value with changes in fair value recognized in earnings each period. The election is made on an instrument by instrument basis at initial recognition of an asset or liability or upon an event that gives rise to a new basis of accounting for that instrument. The Company has elected the fair value option for its investments through Cowen Investments, LLC and certain investments it holds though its operating companies. This option has been elected because the Company believes that it is consistent with the manner in which the business is managed as well as the way that financial instruments in other parts of the business are recorded. Securities — Securities with values based on quoted market prices in active markets for identical assets are classified within level 1 of the fair value hierarchy. These securities include active listed equities, certain U.S. government and sovereign obligations, ETF's, mutual funds and certain money market securities. The Company does not adjust the quoted price for such instruments, even in situations where the Company holds a large position and a sale could reasonably impact the quoted price. Certain positions for which trading activity may not be readily visible, consisting primarily of convertible debt, corporate debt and loans and restricted equities, are stated at fair value and classified within level 2 of the fair value hierarchy. The estimated fair values assigned by management are determined in good faith and are based on available information considering, trading activity, broker quotes, quotations provided by published pricing services, counterparties and other market participants, and pricing models using quoted inputs, and do not necessarily represent the amounts which might ultimately be realized. As level 2 investments include positions that are not always traded in active markets and/or are subject to transfer restrictions, valuations may be adjusted to reflect illiquidity and/or non-transferability. Derivative contracts — Derivative contracts can be exchange-traded or privately negotiated over-the-counter (“OTC”). Exchange-traded derivatives, such as futures contracts and exchange-traded option contracts, are typically classified within level 1 or level 2 of the fair value hierarchy depending on whether or not they are deemed to be actively traded. OTC derivatives, such as generic forwards, swaps and options, have inputs which can generally be corroborated by market data and are therefore classified within level 2. OTC derivatives, such as swaps and options where market data is not readily available or observable are classified as level 3. Other investments — Other investments consist primarily of portfolio funds, real estate investments and equity method investments, which are valued as follows : i. Portfolio funds— Portfolio funds (“Portfolio Funds”) include interests in funds and investment companies which may be managed by the Company or its affiliates. The Company follows US GAAP regarding fair value measurements and disclosures relating to investments in certain entities that calculate net asset value (“NAV”) per share (or its equivalent). The guidance permits, as a practical expedient, an entity holding investments in certain entities that either are investment companies as defined by the AICPA Audit and Accounting Guide, Investment Companies, or have attributes similar to an investment company, and calculate net asset value per share or its equivalent for which the fair value is not readily determinable, to measure the fair value of such investments on the basis of that NAV per share, or its equivalent, without adjustment. In accordance with US GAAP, investments which are valued using NAV per share as a practical expedient shall not be categorized within the fair value hierarchy. ii. Real estate investments— Real estate debt and equity investments are valued at fair value. The fair value of real estate investments are estimated based on the price that would be received to sell an asset in an orderly transaction between marketplace participants at the measurement date. Real estate investments without a public market are valued based on assumptions and valuation techniques used by the Company. Such valuation techniques may include discounted cash flow analysis, prevailing market capitalization rates or earnings multiples applied to earnings from the investment, analysis of recent comparable sales transactions, actual sale negotiations and bona fide purchase offers received from third parties, consideration of the amount that currently would be required to replace the asset, as adjusted for obsolescence, as well as independent external appraisals. In general, the Company considers several valuation techniques when measuring the fair value of a real estate investment. However, in certain circumstances, a single valuation technique may be appropriate. Real estate investments are reviewed on a quarterly basis by the Company for significant changes at the property level or a significant change in the overall market which would impact the value of the real estate investment resulting in unrealized appreciation or depreciation. Real estate and capital markets are cyclical in nature. Property and investment values are affected by, among other things, the availability of capital, occupancy rates, rental rates and interest and inflation rates. In addition, the Company invests in real estate and real estate related investments for which no liquid market exists. The market prices for such investments may be volatile and may not be readily ascertainable. Amounts ultimately realized by the Company from investments sold may differ from the fair values presented, and the differences could be material. The Company's real estate investments are typically categorized as a level 3 investment within the fair value hierarchy as management uses significant unobservable inputs in determining their estimated fair value. See Notes 5 and 6 for further information regarding the Company's investments, including equity method investments, and fair value measurements.
Securities borrowed and securities loaned and repurchase agreements	Securities borrowed and securities loaned Securities borrowed and securities loaned are carried at the amounts of cash collateral advanced or received on a gross basis. The related rebates are recorded in the statement of operations as interest income and interest expense. Securities borrowed transactions require the Company to deposit cash collateral with the lender. With respect to securities loaned, the Company receives cash collateral from the borrower. The initial collateral advanced or received approximates or is greater than the market value of securities borrowed or loaned. The Company monitors the market value of securities borrowed and loaned on a daily basis, with additional collateral obtained or returned, as necessary. Securities borrowed and loaned may also result in credit exposures for the Company in an event that the counterparties are unable to fulfill their contractual obligations. The Company minimizes its credit risk by continuously monitoring its credit exposure and collateral values by demanding additional or returning excess collateral in accordance with the netting provisions available in the master securities lending contracts in place with the counterparties. Fees and interest received or paid are recorded in interest and dividend income and interest expense, respectively, on an accrual basis. In cases where the fair value basis of accounting is elected, any resulting change in fair value is reported in trading revenues. Accrued interest income and expense are recorded in the same manner as under the accrual method. During the fourth quarter of 2014, the Company made a decision to wind down the operations of its securities lending business. At December 31, 2014 , the Company did not have any securities lending transactions for which fair value basis of accounting was elected.
Debt	Debt Long-term debt is carried at the principal amount borrowed net of any discount/premium. The discount is accreted to interest expense using the effective interest method over the remaining life of the underlying debt obligations. Accrued but unpaid coupon interest is included in accrued expenses and other liabilities in the accompanying consolidated statements of financial condition.
Deferred rent	Deferred rent Deferred rent primarily consists of step rent, allowances from landlords and valuing the Company's lease properties in accordance with US GAAP. Step rent represents the difference between actual operating lease payments due and straight-line rent expense, which is recorded by the Company over the term of the lease, including the build-out period. This amount is recorded as deferred rent in the early years of the lease, when cash payments are generally lower than straight-line rent expense, and reduced in the later years of the lease when payments begin to exceed the straight-line expense. Landlord allowances are generally comprised of amounts received and/or promised to the Company by landlords and may be received in the form of cash or free rent. These allowances are part of the negotiated terms of the lease. The Company records a receivable from the landlord and a deferred rent liability when the allowances are earned. This deferred rent is amortized into income (through lower rent expense) over the term (including the pre-opening build-out period) of the applicable lease, and the receivable is reduced as amounts are received from the landlord. Liabilities resulting from valuing the Company's leased properties acquired through business combinations are quantified by comparing the current fair value of the leased space to the current rental payments on the date of acquisition. Deferred rent, included in accounts payable, accrued expenses and other liabilities in the accompanying consolidated statements of financial condition, as of September 30, 2015 and December 31, 2014 is $12.2 million and $13.1 million , respectively.
New accounting pronouncements	Recently issued accounting pronouncements In September 2015, as part of its simplification initiative, FASB issued a new accounting pronouncement which eliminates the concept of measurement period adjustments in a business combination transaction. The amendments require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendments also require that the acquirer record, in the same period’s financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date and eliminate the current requirement to retrospectively account for those adjustments. For public business entities the guidance is effective prospectively for reporting periods beginning after December 15, 2015. The Company is currently evaluating the impact of this guidance on the Company’s financial condition, results of operations and cash flows. In May 2015, the FASB amended the guidance for fair value measurement and issued the amendment which removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share as practical expedient. The amendment also removes the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the net asset value per share as practical expedient. For public companies, the guidance is effective retrospectively for the reporting periods beginning after December 15, 2015 and early adoption is permitted. During the quarter ended June 30, 2015, the Company early adopted the guidance and excluded the investments measured at fair value using the net asset value per share as practical expedient from the fair value hierarchy. The adoption did not result in any impact on the Company’s financial condition, result of operations and cash flows. See Note 6 which reflects the impact of adopting this guidance and further information. In April 2015, the FASB issued a new accounting pronouncement simplifying the presentation of debt issuance costs. The accounting guidance requires that debt issuance costs related to a recognized debt liability be reported on the Consolidated Statements of Financial Condition as a direct deduction from the carrying amount of that debt liability. The guidance is effective retrospectively for reporting periods beginning after December 15, 2015 and early adoption is permitted. In August 2015, FASB issued another pronouncement amending the SEC guidance pursuant to this amendment. The adoption of this accounting guidance is not expected to have a material impact on the Company’s financial condition. In May 2014, the FASB issued guidance which amends and supersedes the revenue recognition requirements and most industry-specific guidance and creates a single source of revenue guidance. The new guidance outlines the principles an entity must apply to measure and recognize revenue and related cash flows. The guidance also provides a model for the measurement and recognition of gains and losses on the sale of certain non-financial assets. The guidance is effective for reporting periods beginning after December 15, 2017. In July 2015, the FASB confirmed a deferral of the effective date by one year, with early adoption on the original effective date permitted. The Company is currently evaluating the impact of this guidance on the Company’s financial condition, results of operations and cash flows. In February 2015, the FASB issued an accounting pronouncement which amends and updates its previous guidance regarding consolidation analysis. The amendment eliminates the deferral of certain consolidation standards for entities considered to be investment companies and modifies the consolidation analysis performed on certain types of legal entities. The guidance is effective for reporting periods beginning after December 15, 2015. The Company is currently evaluating the impact of the new guidance on our consolidated financial statements. In January 2015, the FASB issued a new accounting pronouncement regarding extraordinary items. The guidance eliminates the concept and presentation requirements for extraordinary items and issuers are no longer required to evaluate and present separately any transaction which is unusual and infrequent. The guidance is effective for reporting periods beginning after December 15, 2015. The Company does not expect this guidance to have any impact on its financial position and results of operations.
Earnings Per Share	Diluted earnings per common share are calculated by adjusting the weighted average outstanding shares to assume conversion of all potentially dilutive items. The Company uses the treasury stock method to reflect the potential dilutive effect of the warrants (see Note 5 (a)), unexercised stock options, unvested restricted shares, restricted stock units, and SAR's. In calculating the number of dilutive shares outstanding, the shares of common stock underlying unvested restricted shares and restricted stock units are assumed to have been delivered, and options and warrants are assumed to have been exercised, on the grant date. The assumed proceeds from the assumed vesting, delivery and exercising were calculated as the sum of (a) the amount of compensation cost attributed to future services and not yet recognized and (b) the amount of tax benefit that would be credited to additional paid-in capital assuming vesting and delivery of the shares. The tax benefit is the amount resulting from a tax deduction for compensation in excess of compensation expense recognized for financial statement reporting purposes. All outstanding warrants were not included in the computation of diluted net income (loss) per common share for the three and nine months ended September 30, 2015 and 2014, respectively, as their inclusion would have been anti-dilutive.
Segment Reporting	The performance measure for these segments is Economic Income (Loss), which management uses to evaluate the financial performance of and make operating decisions for the segments including determining appropriate compensation levels. Expenses not directly associated with specific segments are allocated based on the most relevant measures applicable, including headcount, square footage and other factors. In general, Economic Income (Loss) is a pre-tax measure that (i) eliminates the impact of consolidation for consolidated funds (ii) excludes goodwill and intangible impairment (iii) excludes certain other acquisition-related and/or reorganization expenses and (iv) excludes preferred stock dividends. In addition, Economic Income (Loss) revenues include investment income that represents the income the Company has earned in investing its own capital, including realized and unrealized gains and losses, interest and dividends, net of associated investment related expenses. For US GAAP purposes, these items are included in each of their respective line items. Economic Income (Loss) revenues also include management fees, incentive income and investment income earned through the Company's investment as a general partner in certain real estate entities and the Company's investment in the activist business. For US GAAP purposes, all of these items are recorded in other income (loss). In addition, Economic Income (Loss) expenses are reduced by reimbursement from affiliates, which for US GAAP purposes is presented gross as part of revenue. As further stated below, one major difference between Economic Income (Loss) and US GAAP net income (loss) is that Economic Income (Loss) presents the segments' results of operations without the impact resulting from the full consolidation of any of the Consolidated Funds. Consolidation of these funds results in including in income the pro rata share of the income or loss attributable to other owners of such entities which is reflected in net income (loss) attributable to redeemable non-controlling interest in consolidated subsidiaries in the accompanying consolidated statements of operations. This pro rata share has no effect on the overall financial performance for the alternative investment segment, as ultimately, this income or loss is not income or loss for the alternative investment segment itself. Included in Economic Income (Loss) is the actual pro rata share of the income or loss attributable to the Company as an investor in such entities, which is relevant in management making operating decisions and evaluating financial performance.

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2015
Acquisition [Abstract]
Business Acquisition, Pro Forma Information	The following unaudited supplemental pro forma information presents condensed consolidated financial results for the nine month periods as if the acquisition was completed as of January 1, 2014. This supplemental pro forma information has been prepared for comparative purposes only and is not intended to be indicative of what the Company's results would have been had the acquisition been completed on January 1, 2014, nor does it purport to be indicative of any future results. For the nine months ended September, 30 2015 2014 (dollars in thousands, except per share data) (unaudited) Revenues $ 375,651 $ 328,677 Net income (loss) attributable to Cowen Group, Inc. common stockholders 12,952 24,840 Net income per common share: Basic $ 0.12 $ 0.21 Diluted $ 0.11 $ 0.21

Investments of Operating Enti32

Investments of Operating Entities and Consolidated Funds - Quarterly (Tables)	9 Months Ended
	Sep. 30, 2015
Investment Holdings [Line Items]
Marketable Securities	As of September 30, 2015 and December 31, 2014 , securities owned, at fair value consisted of the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) U.S. Government securities (a) $ 3,015 $ 2,010 Preferred stock 15,771 15,070 Common stocks 712,489 597,476 Convertible bonds (b) 1,129 900 Corporate bonds (c) 113,585 159,557 Warrants and rights 3,871 1,417 Mutual funds 14,825 15,776 $ 864,685 $ 792,206 (a) As of September 30, 2015 , maturities ranged from December 2015 to August 2016 with interest rates ranged between 0% to 5.95% . As of December 31, 2014 , maturities ranged from May 2015 to April 2016 with interest rates ranged between 0% to 5.95% . (b) As of September 30, 2015 , maturities ranged from July 2016 to March 2018 with interest rates ranged between 8% to 10.00% . As of December 31, 2014 , the maturity was February 2015 with an interest rate of 10.00% . (c) As of September 30, 2015 , maturities ranged from March 2016 to February 2046 and interest rates ranged between 3.17% to 21.74% . As of December 31, 2014 , maturities ranged from February 2015 to February 2046 and interest rates ranged between 5.63% to 11.54% .
Schedule of Derivative Instruments	The Company's long and short exposure to derivatives is as follows: Receivable on derivative contracts As of September 30, 2015 As of December 31, 2014 Number of contracts / Notional Value Fair value Number of contracts / Notional Value Fair value (dollars in thousands) Futures $ 4,679 $ 68 $ 3,041 $ 75 Currency forwards $ 34,036 105 $ 23,961 310 Equity swaps $ 52,000 470 $ 12,904 251 Options other (a) 306,659 34,498 367,441 48,201 Foreign currency options $ 292,475 6,446 $ 32,200 1,040 $ 41,587 $ 49,877 (a) Includes index, equity, commodity future and cash conversion options. Payable for derivative contracts As of September 30, 2015 As of December 31, 2014 Number of contracts / Notional Value Fair value Number of contracts / Notional Value Fair value (dollars in thousands) Futures $ 32,423 $ 381 $ 2,213 $ 33 Currency forwards $ 43,788 107 $ — — Equity and credit default swaps $ 45,193 2,615 $ 18,352 1,603 Options other (a) 14,035 22,975 22,043 39,694 $ 26,078 $ 41,330 (a) Includes index, equity, commodity future and cash conversion options. The following tables present the gross and net derivative positions and the related offsetting amount, as of September 30, 2015 and December 31, 2014 . Gross amounts not offset in the Statement of Financial Condition Gross amounts recognized Gross amounts offset on the Consolidated Statements of Financial Condition (a) Net amounts included on the Consolidated Statements of Financial Condition Financial instruments Cash Collateral pledged (b) Net amounts (dollars in thousands) As of September 30, 2015 Receivable on derivative contracts, at fair value $ 41,587 $ — $ 41,587 $ — $ 8,950 $ 32,637 Payable for derivative contracts, at fair value 26,078 — 26,078 — 2,643 23,435 As of December 31, 2014 Receivable on derivative contracts, at fair value 49,877 — 49,877 — 2,588 47,289 Payable for derivative contracts, at fair value 41,330 — 41,330 — 1,603 39,727 (a) Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred. (b) Includes the amount of collateral held or posted.
Schedule of Other Investments	As of September 30, 2015 and December 31, 2014 , other investments included the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) (1) Portfolio Funds, at fair value $ 108,509 $ 103,466 (2) Real estate investments, at fair value 1,916 2,175 (3) Equity method investments 42,574 61,443 (4) Lehman claims, at fair value 335 380 $ 153,334 $ 167,464
Schedule of Other Investments, Portfolio Funds	The Portfolio Funds, at fair value as of September 30, 2015 and December 31, 2014 , included the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) HealthCare Royalty Partners (a)(*) $ 12,016 $ 11,935 HealthCare Royalty Partners II (a)(*) 7,439 6,648 Orchard Square Partners Credit Fund LP (b) 4,473 11,532 Starboard Value and Opportunity Fund LP (c)(*) 20,914 21,792 Starboard Partners Fund LP (d)(*) 13,785 14,652 Starboard Leaders Fund LP (e)(*) 1,251 1,367 Formation8 Partners Fund I, L.P. (f) 17,364 11,283 Formation8 Partners Hardware Fund I, L.P. (g) 1,125 — RCG LV Park Lane LLC (h) (*) 1,364 642 RCGL 12E13th LLC (i) (*) 632 638 RCG Longview Debt Fund V, L.P. (i) (*) 14,745 12,876 RCG LPP SME Co-Invest, L.P. (j) (*) 2,469 — Other private investment (k) 6,591 7,324 Other affiliated funds (l)(*) 4,341 2,777 $ 108,509 $ 103,466 * These portfolio funds are affiliates of the Company. The Company has no unfunded commitments regarding the portfolio funds held by the Company except as noted in Note 13 . (a) HealthCare Royalty Partners, L.P. and HealthCare Royalty Partners II, L.P. are private equity funds and therefore distributions will be made when cash flows are received from the underlying investments, typically on a quarterly basis. (b) Orchard Square Partners Credit Fund LP has a quarterly redemption policy with a 60 day notice period and a 4% penalty on redemptions of investments of less than a year in duration. (c) Starboard Value and Opportunity Fund LP permits quarterly withdrawals upon 90 days notice. (d) Starboard Partners Fund LP permits redemptions on a semi-annual basis on 180 days prior written notice subsequent to an initial two year lock up. (e) Starboard Leaders Fund LP does not permit withdrawals, but instead allows terminations with respect to capital commitments upon 30 days prior written notice at any time following the first anniversary of an investors initial capital contribution. (f) Formation8 Partners Fund I, L.P. is a private equity fund which invests in early stage and growth transformational information and energy technology companies. Distributions will be made when the underlying investments are liquidated. (g) Formation8 Partners Hardware Fund I, L.P. is a private equity fund which invests in early stage and growth hardware companies. Distributions will be made when the underlying investments are liquidated. (h) RCG LV Park Lane LLC is a single purpose entity formed to participate in a joint venture which acquired, at a discount, the mortgage notes on a portfolio of multifamily real estate properties located in Birmingham, Alabama. RCG LV Park Lane LLC is a private equity structure and therefore distributions will be made when the underlying investments are liquidated. (i) RCGL 12E13th LLC and RCG Longview Debt Fund V, L.P. are real estate private equity structures and therefore distributions will be made when the underlying investments are liquidated. (j) RCG LPP SME Co-Invest, L.P. is a single purpose entity formed to participate in a joint venture which acquired two fully entitled residential development sites in the New York City metro area. RCG LPP SME Co-Invest, L.P. is a private equity structure and therefore distributions will be made when the underlying investments are liquidated. (k) Other private investment represents the Company's closed end investment in a portfolio fund that invests in a wireless broadband communication provider in Italy. (l) The majority of these funds are affiliates of the Company or are managed by the Company and the investors can redeem from these funds as investments are liquidated.
Schedule of Other Investments, Equity Method	The following table summarizes equity method investments held by the Company: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) RCG Longview Debt Fund IV Management, LLC $ 464 $ 676 RCG Longview Debt Fund V Partners, LLC 3,988 2,684 HealthCare Royalty GP, LLC 980 973 HealthCare Royalty GP II, LLC 1,260 1,125 HealthCare Royalty GP III, LLC 71 62 CBOE Stock Exchange, LLC 568 611 Starboard Value LP 30,079 48,772 RCG Longview Partners, LLC — 237 RCG Longview Management, LLC 1,287 1,117 RCG Urban American, LLC 122 422 RCG Urban American Management, LLC 379 379 RCG Longview Equity Management, LLC 250 316 Urban American Real Estate Fund II, LLC 1,975 2,329 RCG Kennedy House, LLC 268 509 Other 883 1,231 $ 42,574 $ 61,443 For the period ended September 30, 2015 , two equity method investment held by the Company met the significance criteria as defined under applicable SEC guidance. As such, the Company is required to present summarized financial information for these significant investees for the three and nine months ended September 30, 2015 and 2014. The summarized income statement information for the Company's investments in the individually significant investees is as follows: Other equity method investment Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (dollars in thousands) Revenues $ (3,216 ) $ 13,258 $ 8,249 $ 21,956 Expenses (2,033 ) (7,772 ) (1,927 ) (5,349 ) Net realized and unrealized gains (losses) (155 ) (40 ) 51 165 Net Income $ (5,404 ) $ 5,446 $ 6,373 $ 16,772
Schedule of Securities Sold, Not yet Purchased	As of September 30, 2015 and December 31, 2014 , securities sold, not yet purchased, at fair value consisted of the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Common stocks $ 250,680 $ 207,815 Corporate bonds (a) 59 60 $ 250,739 $ 207,875 (a) As of September 30, 2015 and December 31, 2014 , the maturity was January 2026 with an interest rate of 5.55% .
Securities Borrowed and Securities Loaned	Securities lending and borrowing transactions The following tables present the contractual gross and net securities borrowing and lending agreements and the related offsetting amount, as of December 31, 2014 . During the first quarter of 2015 this business was completely liquidated. Gross amounts not offset in the Statement of Financial Condition Gross amounts recognized Gross amounts offset on the Consolidated Statements of Financial Condition (a) Net amounts included on the Consolidated Statements of Financial Condition Additional Amounts Available Financial instruments Cash Collateral pledged (b) Net amounts (dollars in thousands) As of December 31, 2014 Securities borrowed $ 676,100 $ — $ 676,100 $ (15,655 ) $ (660,445 ) $ — $ — Securities loaned 682,493 — 682,493 (2,441 ) (680,052 ) — — (a) Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred. (b) Includes the amount of cash collateral held/posted.
Consolidated Funds
Investment Holdings [Line Items]
Schedule of Other Investments	Other investments, at fair value As of September 30, 2015 and December 31, 2014 other investments, at fair value, held by the Consolidated Funds are comprised of: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) (1) Portfolio Funds $ 255,896 $ 188,884 (2) Lehman claims — 493 $ 255,896 $ 189,377
Schedule of Other Investments, Portfolio Funds	Investments in Portfolio Funds, at fair value As of September 30, 2015 and December 31, 2014 , investments in Portfolio Funds, at fair value, included the following: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Investments of Enterprise LP $ 122,858 $ 138,253 Investments of Merger Fund 60,432 50,631 Investments of Quadratic LLC 72,606 — $ 255,896 $ 188,884
Enterprise Master
Investment Holdings [Line Items]
Schedule of Derivative Instruments	Receivable/(Payable) on derivative contracts, at fair value, owned by Enterprise Master As of September 30, 2015 As of December 31, 2014 Description (dollars in thousands) Currency forwards $ (4 ) $ 64 $ (4 ) $ 64
Schedule of Securities Owned	Securities owned by Enterprise Master, at fair value As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Bank debt $ — $ 20 Common stock 1,657 1,659 Preferred stock 626 576 Private equity — 587 Restricted stock 124 124 Rights 2,715 2,802 Trade claims 128 128 $ 5,250 $ 5,896
Schedule of Other Investments, Portfolio Funds	Portfolio Funds, owned by Enterprise Master, at fair value As of September 30, 2015 As of December 31, 2014 Strategy (dollars in thousands) RCG Longview Equity Fund, LP* Real Estate $ 7,637 $ 9,090 RCG Longview II, LP* Real Estate 785 747 RCG Longview Debt Fund IV, LP* Real Estate 3,999 5,348 RCG Longview, LP* Real Estate — 40 RCG Soundview, LLC* Real Estate 452 452 RCG Urban American Real Estate Fund, L.P.* Real Estate 648 1,161 RCG International Sarl* Multi-Strategy 1,220 2,113 RCG Special Opportunities Fund, Ltd* Multi-Strategy 89,303 92,405 RCG Energy, LLC * Energy 1,398 2,294 RCG Renergys, LLC* Energy 1 1 Other Private Investments Various 10,629 12,057 Other Real Estate Investments (*) Real Estate 5,731 10,138 $ 121,803 $ 135,846 * Affiliates of the Company.
Merger Master
Investment Holdings [Line Items]
Marketable Securities	Securities owned by Merger Master, at fair value As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Common stocks $ 179,650 $ 133,510 Corporate bonds (a) — 3,383 $ 179,650 $ 136,893 (a) As of December 31, 2014 , maturities ranged from February 2017 to June 2019 and interest rates ranged between 8.50% and 9.75%
Schedule of Derivative Instruments	Receivable on derivative contracts, at fair value, owned by Merger Master As of September 30, 2015 As of December 31, 2014 Description (dollars in thousands) Options $ 604 $ 541 Currency forwards 22 — Equity swaps 150 76 $ 776 $ 617 Payable for derivative contracts, at fair value, owned by Merger Master As of September 30, 2015 As of December 31, 2014 Description (dollars in thousands) Options $ 36 $ 238 Exchange traded fund 3,801 — Equity swaps 862 56 $ 4,699 $ 294
Quadratic Master
Investment Holdings [Line Items]
Schedule of Derivative Instruments	The Company's long and short exposure to derivatives is as follows: Receivable on derivative contracts, at fair value, owned by Quadratic Master As of September 30, 2015 Description (dollars in thousands) Options $ 9,622 Currency forwards 32 $ 9,654 As of September 30, 2015 , Quadratic Master held options payable for derivative, of $0.1 million .
Schedule of Other Investments, Portfolio Funds	Securities owned by Quadratic Master, at fair value As of September 30, 2015 (dollars in thousands) Common stocks $ 267 U.S. Government securities (a) 15,000 $ 15,267 (a) As of September 30, 2015 , the maturity was October 2015 with an interest rate of 0% .

Fair Value Measurements for O33

Fair Value Measurements for Operating Entities and Consolidated Funds (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the assets and liabilities that are measured at fair value on a recurring basis on the accompanying consolidated statements of financial condition by caption and by level within the valuation hierarchy as of September 30, 2015 and December 31, 2014 : Assets at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (dollars in thousands) Operating Entities Securities owned US Government securities $ 3,015 $ — $ — $ 3,015 Preferred stock — — 15,771 15,771 Common stocks 689,252 22,920 317 712,489 Convertible bonds — — 1,129 1,129 Corporate bonds — 113,585 — 113,585 Warrants and rights 877 — 2,994 3,871 Mutual funds 14,825 — — 14,825 Receivable on derivative contracts, at fair value — Futures 68 — — 68 Currency forwards — 105 — 105 Equity swaps — 470 — 470 Options 10,277 9,076 21,591 40,944 Other investments Real estate investments — — 1,916 1,916 Lehman claim — — 335 335 Consolidated funds Preferred stock — — 19,000 19,000 $ 718,314 $ 146,156 $ 63,053 $ 927,523 Percentage of total assets measured at fair value 77.4 % 15.8 % 6.8 % Portfolio funds measured at net asset value (a) 108,509 Consolidated funds' portfolio funds measured at net asset value (a) 255,896 Equity method investments 42,574 Total investments $ 1,334,502 Liabilities at Fair Value as of September 30, 2015 Level 1 Level 2 Level 3 Total (dollars in thousands) Securities sold, not yet purchased Common stocks $ 250,680 $ — $ — $ 250,680 Corporate bonds — 59 — 59 Payable for derivative contracts, at fair value Futures 381 — — 381 Currency forwards 107 — 107 Equity and credit default swaps 2,615 — 2,615 Options 1,384 — 21,591 22,975 Accounts payable, accrued expenses and other liabilities Contingent consideration liability (b) — — 5,458 5,458 $ 252,445 $ 2,781 $ 27,049 $ 282,275 Percentage of total liabilities measured at fair value 89.4 % 1.0 % 9.6 % (a) In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition. (b) In accordance with the terms of the purchase agreements for acquisitions that closed during 2012 and the third quarter of 2015, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the periods ended August 2016 and December 2020, respectively. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts as of September 30, 2015 can range from zero to $6.7 million . Assets at Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total (dollars in thousands) Operating Entities Securities owned US Government securities $ 2,010 $ — $ — $ 2,010 Preferred stock — 2,553 12,517 15,070 Common stocks 578,934 18,130 412 597,476 Convertible bonds — — 900 900 Corporate bonds — 159,557 — 159,557 Warrants and rights 95 — 1,322 1,417 Mutual funds 15,776 — — 15,776 Receivable on derivative contracts, at fair value Futures 75 — — 75 Currency forwards — 310 — 310 Equity swaps — 251 — 251 Options 10,462 1,972 36,807 49,241 Other investments Real estate investments — — 2,175 2,175 Lehman claim — — 380 380 Consolidated funds Lehman claim — — 493 493 $ 607,352 $ 182,773 $ 55,006 $ 845,131 Percentage of total assets measured at fair value 71.9 % 21.6 % 6.5 % Portfolio funds measured at net asset value (a) 103,466 Consolidated funds' portfolio funds measured at net asset value (a) 188,884 Equity method investments 61,443 Total investments $ 1,198,924 Liabilities at Fair Value as of December 31, 2014 Level 1 Level 2 Level 3 Total (dollars in thousands) Securities sold, not yet purchased Common stocks $ 207,815 $ — $ — $ 207,815 Corporate bonds — 60 — 60 Payable for derivative contracts, at fair value Futures 33 — — 33 Equity and credit default swaps — 1,603 — 1,603 Options 2,887 — 36,807 39,694 Accounts payable, accrued expenses and other liabilities Contingent consideration liability (b) — — 4,083 4,083 $ 210,735 $ 1,663 $ 40,890 $ 253,288 Percentage of total liabilities measured at fair value 83.2 % 0.7 % 16.1 % (a) In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition. (b) In accordance with the terms of a purchase agreement for an acquisitions that closed during 2012, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the period ended August 2016. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts can range from $0.9 million to $7.1 million .
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following table includes a rollforward of the amounts for the three and nine months ended September 30, 2015 and 2014 , for financial instruments classified within level 3. The classification of a financial instrument within level 3 is based upon the significance of the unobservable inputs to the overall fair value measurement. Three Months Ended September 30, 2015 Balance at June 30, 2015 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2015 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 23,462 $ — $ (9,000 ) (a) (b) $ 3,500 $ (6,665 ) $ 4,474 $ 15,771 $ 1,200 Common stocks 404 — — 104 (89 ) (102 ) 317 (87 ) Convertible bonds 879 — — 250 — — 1,129 — Options, asset 58,576 — — — — (36,985 ) 21,591 (36,985 ) Options, liability 58,576 — — — — (36,985 ) 21,591 (36,985 ) Warrants and rights 2,316 — — — — 678 2,994 878 Real estate 1,987 — — — (70 ) (1 ) 1,916 (1 ) Lehman claim 347 — — — — (12 ) 335 (12 ) Contingent consideration liability 2,358 — — 3,100 — — 5,458 — Consolidated Funds Preferred stock — — 7,000 (b) 12,000 — — 19,000 — Lehman claim 744 — — — (739 ) (5 ) — — Three Months Ended September 30, 2014 Balance at June 30, 2014 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2014 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 2,574 $ — $ (2,000 ) (a) $ — $ — $ — $ 574 $ — Common stocks 419 — — — (1 ) (128 ) 290 (14 ) Convertible bonds 1,750 — — — — — 1,750 — Options, asset 37,658 — — — — (8,873 ) 28,785 (8,873 ) Options, liability 37,658 — — — — (8,873 ) 28,785 (8,873 ) Warrants and rights 3,346 — — 57 (57 ) (738 ) 2,608 (434 ) Real estate 2,262 — — — — 23 2,285 23 Lehman claim 418 — — — — (58 ) 360 (58 ) Contingent consideration liability 6,783 — — — (364 ) — 6,419 — Consolidated Funds Lehman claim 4,090 — — — (3,731 ) 2 361 2 Nine Months Ended September 30, 2015 Balance at December 31, 2014 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2015 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 12,517 $ — $ (15,823 ) (a) (b) $ 21,750 $ (6,665 ) $ 3,992 $ 15,771 $ 717 Common stocks 412 — — 104 (120 ) (79 ) 317 (74 ) Convertible bonds 900 — — 250 — (21 ) 1,129 (21 ) Options, asset 36,807 — — — — (15,216 ) 21,591 (15,216 ) Options, liability 36,807 — — — — (15,216 ) 21,591 (15,216 ) Warrants and Rights 1,322 — — 26 (71 ) 1,717 2,994 1,757 Real estate 2,175 — — — (377 ) 118 1,916 118 Lehman claim 380 — — — — (45 ) 335 (45 ) Contingent consideration liability 4,083 — — 3,100 (1,725 ) — 5,458 — Consolidated Funds Preferred stock — — 7,000 (b) 12,000 — — 19,000 — Lehman claim 493 — — — (739 ) 246 — — Nine Months Ended September 30, 2014 Balance at December 31, 2013 Transfers in Transfers out Purchases/(covers) (Sales)/shorts Realized and Unrealized gains/losses Balance at September 30, 2014 Change in unrealized gains/losses relating to instruments still held (1) (dollars in thousands) Operating Entities Preferred stock $ 324 $ — $ (2,000 ) (a) $ 2,250 $ — $ — $ 574 $ — Common stocks 3,559 — (3,150 ) (a) 9 (1 ) (127 ) 290 (13 ) Convertible bonds 1,950 — — — (200 ) — 1,750 — Options, asset — — — 35,710 — (6,925 ) 28,785 (6,925 ) Options, liability — — — 35,710 — (6,925 ) 28,785 (6,925 ) Warrants and Rights, asset 5,805 — — 57 (1,385 ) (1,869 ) 2,608 (432 ) Real estate 2,088 — — 50,000 (50,027 ) 224 2,285 224 Lehman claim 378 — — — (76 ) 58 360 58 Contingent consideration liability 6,937 — — — (518 ) — 6,419 — Consolidated Funds Lehman claim 4,842 — — — (4,711 ) 230 361 230 (1) Unrealized gains/losses are reported in other income (loss) in the accompanying consolidated statements of operations. (a) The company completed an initial public offering. (b) The company transferred investments to a consolidated fund.
Fair Value Inputs, Assets, Quantitative Information	The following table includes quantitative information as of September 30, 2015 and December 31, 2014 for financial instruments classified within level 3. The table below quantifies information about the significant unobservable inputs used in the fair value measurement of the Company's level 3 financial instruments. Quantitative Information about Level 3 Fair Value Measurements Fair Value at September 30, 2015 Valuation techniques Unobservable Inputs Range Level 3 Assets (dollars in thousands) Common and preferred stocks $ 3,110 Market/transaction multiples and option pricing method Volatility Market multiples 42% 1x to 5.25x Convertible bonds 1,129 Recovery analysis Recovery rate 50% Warrants and rights, net 2,994 Model based Volatility 17% to 60% (weighted average 29%) Options 21,591 Option pricing models Volatility 29% Other level 3 assets (a) 34,229 Total level 3 assets 63,053 Level 3 Liabilities Options 21,591 Option pricing models Volatility 29% Contingent consideration 5,458 Discounted cash flows Projected cash flow and discount rate 9% - 24.5% (weighted average 18%) Total level 3 liabilities $ 27,049 Quantitative Information about Level 3 Fair Value Measurements Fair Value at December 31, 2014 Valuation techniques Unobservable Inputs Range Level 3 Assets (dollars in thousands) Common and preferred stocks $ 12,269 Market multiples and option pricing method Volatility Market multiples 45% 1x to 6x Convertible bonds 900 Recovery analysis Recovery rate 50% Warrants and rights, net 1,322 Model based Volatility 20% to 60% (weighted average 34%) Options 36,807 Option pricing models Volatility Credit spreads 30% to 40% 500bps - 750 bps Other level 3 assets (a) 3,708 Total level 3 assets 55,006 Level 3 Liabilities Options 36,807 Option pricing models Volatility Credit spreads 30% to 40% 500bps - 750 bps Contingent consideration 4,083 Discounted cash flows Projected cash flow and discount rate 9% Total level 3 liabilities $ 40,890 (a) The quantitative disclosures exclude financial instruments for which the determination of fair value is based on prices from prior transactions and investments for which NAV per share is used as a practical expedient to determine fair value.
Fair Value Measurements, Nonrecurring	The following table presents the carrying values and fair values, at September 30, 2015 and December 31, 2014 , of financial assets and liabilities and information on their classification within the fair value hierarchy which are not measured at fair value on a recurring basis. For additional information regarding the financial instruments within the scope of this disclosure, and the methods and significant assumptions used to estimate their fair value see Note 3 . September 30, 2015 December 31, 2014 Fair Value Hierarchy Carrying Amount Fair Value Carrying Amount Fair Value (dollars in thousands) Financial Assets Operating companies Cash and cash equivalents $ 92,854 $ 92,854 $ 129,509 $ 129,509 Level 1 Cash collateral pledged 9,129 9,129 8,306 8,306 Level 2 Securities borrowed — — 676,100 660,445 Level 1 Consolidated funds Cash and cash equivalents 16,625 16,625 501 501 Level 1 Financial Liabilities Securities loaned — — 682,493 661,533 Level 1 Convertible debt 123,149 (a) 158,470 (b) 118,475 (a) 160,713 (b) Level 2 Notes payable and other debt 66,628 69,436 67,144 69,548 Level 2 (a) The carrying amount of the convertible debt includes an unamortized discount of $26.4 million and $31.0 million as of September 30, 2015 and December 31, 2014 . (b) The convertible debt include the conversion option and is based on the last broker quote available.

Redeemable Non-Controlling In34

Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds (Tables)	9 Months Ended
	Sep. 30, 2015
Noncontrolling Interest [Abstract]
Redeemable non-controlling interests in consolidated subsidiaries and funds	Redeemable non-controlling interests in consolidated subsidiaries and funds and the related net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds are comprised as follows: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Redeemable non-controlling interests in consolidated subsidiaries and funds Operating companies $ 15,730 $ 9,619 Consolidated funds 155,515 76,457 $ 171,245 $ 86,076
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (dollars in thousands) Income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds Operating companies $ 4,577 $ 3,223 $ 8,669 $ 9,690 Consolidated funds (233 ) 783 2,311 3,719 $ 4,344 $ 4,006 $ 10,980 $ 13,409

Share-Based Compensation and 35

Share-Based Compensation and Employee Ownership Plans (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Stock Options, Activity	The following table summarizes the Company's stock option activity for the nine months ended September 30, 2015 : Shares Subject Weighted Average Weighted Average Aggregate Intrinsic (in years) (dollars in thousands) Balance outstanding at December 31, 2014 216,672 $ 5.65 1.60 $ 87 Options granted — — — — Options exercised (100,002 ) 3.96 — — Options expired (100,003 ) 7.49 — — Balance outstanding at September 30, 2015 16,667 $ 4.89 1.35 $ — Options exercisable at September 30, 2015 16,667 $ 4.89 1.35 $ — (1) Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014 .
Schedule of Share-based Compensation, Stock Appreciation Rights, Activity	As of September 30, 2015 , the unrecognized compensation expense related to the Company's grant of stock options was insignificant. The following table summarizes the Company's SAR's for the nine months ended September 30, 2015 : Shares Subject Weighted Average Weighted Average Aggregate Intrinsic (in years) (dollars in thousands) Balance outstanding at December 31, 2014 400,000 $ 2.90 3.21 $ 913 SAR's granted — — — — SAR's acquired — — — — SAR's expired — — — — Balance outstanding at September 30, 2015 400,000 $ 2.90 2.46 $ 781 SAR's exercisable at September 30, 2015 — $ — — $ — (1) Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014 .
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity	Restricted shares and restricted stock units are referred to collectively as restricted stock. The following table summarizes the Company's restricted share and restricted stock unit activity for the nine months ended September 30, 2015 : Nonvested Restricted Shares and Restricted Stock Units Weighted-Average Balance outstanding at December 31, 2014 17,654,582 $ 3.70 Granted 5,718,605 4.79 Vested (3,992,005 ) 3.08 Canceled — — Forfeited (1,017,758 ) 3.41 Balance outstanding at September 30, 2015 (1) 18,363,424 $ 4.19 (1) Performance linked restricted stock units of 1,925,750 were awarded to employees of the Company in December 2013 and January 2014. Of the awards granted, 326,250 have been forfeited through September 30, 2015 . The remaining awards, included in the outstanding balance as of September 30, 2015 , will vest on June 10, 2019 and will be earned only to the extent that the Company attains specified performance goals relating to its volume-weighted average share price and the aggregate net income for the years from 2014 to 2018. The actual number of RSUs ultimately earned could vary from zero, if performance goals are not met, to as much as 100% of the targeted award. Each RSU is equal to the one share of the Company’s Class A common stock. Compensation expense is recognized to the extent that it is probable that the Company will attain the performance goals.

Defined Benefit Plan - Quarterl

Defined Benefit Plan - Quarterly (Tables)	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule of Net Periodic Benefit Cost	The amounts contained in the following table relate to the Company's defined benefit plan(s) for the three and nine months ended September 30, 2014 : Three Months Ended September 30, 2014 Nine Months Ended September 30, 2014 (dollars in thousands) Components of net periodic benefit cost included in employee compensation and benefits Service cost $ — $ — Interest cost 18 85 Expected return on plan assets (168 ) (300 ) Amortization of loss / (gain) (7 ) (7 ) Amortization of prior service cost — — Effect of settlement — — Net periodic benefit cost $ (157 ) $ (222 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Annual Lease and Service Payments	As of September 30, 2015 , future minimum annual lease and service payments for the Company were as follows: Equipment Leases (a) Service Payments Facility Leases (b) (dollars in thousands) 2015 $ 700 $ 4,490 $ 5,094 2016 2,502 12,391 19,401 2017 2,301 6,245 16,030 2018 2,221 4,162 15,621 2019 813 1,375 14,822 Thereafter — — 47,064 $ 8,537 $ 28,663 $ 118,032 (a) Equipment Leases include the Company's commitments relating to operating and capital leases. See Note 14 for further information on the capital lease minimum payments which are included in the table. (b) The Company has entered into various agreements to sublease certain of its premises. The Company recorded sublease income related to these leases of $0.5 million and $0.5 million for the three months ended September 30, 2015 and 2014 and $1.4 million and $1.3 million for the nine months ended September 30, 2015 and 2014 , respectively.

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Schedule of Debt and Capital Lease Obligations	As of September 30, 2015 and December 31, 2014 , the Company's outstanding debt was as follows: As of September 30, 2015 As of December 31, 2014 (dollars in thousands) Convertible debt $ 123,149 $ 118,475 Note Payable 63,250 63,250 Other Note payable 355 — Capital lease obligations 3,023 3,894 $ 189,777 $ 185,619
Schedule of Maturities of Debt and Future Minimum Lease Payments for Capital Leases	Annual scheduled maturities of debt and minimum payments for all debt outstanding as of September 30, 2015 , is as follows: Convertible Debt Note Payable Other Note Payable Capital Lease (dollars in thousands) 2015 $ — $ 1,304 $ 361 $ 330 2016 4,485 5,218 — 1,025 2017 4,485 5,218 — 938 2018 4,485 5,218 — 938 2019 151,743 5,218 — 78 Thereafter — 73,686 — — Subtotal 165,198 95,862 361 3,309 Less: Amount representing interest (a) (42,049 ) (32,612 ) (6 ) (286 ) Total $ 123,149 $ 63,250 $ 355 $ 3,023 (a) Amount necessary to reduce net minimum payments to present value calculated at the Company's implicit rate at inception. This amount also includes the unamortized discount on the convertible debt.
Schedule of Line of Credit Facilities	As of September 30, 2015 , the Company has the following seven irrevocable letters of credit related to leased office space, for which there is cash collateral pledged, which the Company pays a fee on the stated amount of the letter of credit. Location Amount Maturity (dollars in thousands) San Francisco $ 710 October 2025 New York $ 1,000 February 2016 Boston $ 382 March 2016 New York $ 355 May 2016 New York $ 1,861 May 2016 New York $ 794 October 2016 New York $ 3,935 October 2016

Stockholder's Equity (Tables)

Stockholder's Equity (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Treasury Stock Activity	The following represents the activity relating to the treasury stock held by the Company during the nine months ended September 30, 2015 : Treasury stock shares Cost Average cost Balance outstanding at December 31, 2014 23,507,656 $ 79,771 $ 3.39 Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions 1,574,949 8,556 5.43 Treasury stock reissued — — — Purchase of treasury stock 7,694,214 41,697 5.42 Balance outstanding at September 30, 2015 32,776,819 $ 130,024 $ 3.97

Accumulated Other Comprehensi40

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2015
Accumulated Other Comprehensive Income / (Loss) [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Foreign currency translation (a) Defined benefit plans (a) Total (dollars in thousands) Balance at December 31, 2014 $ 17 $ — $ 17 Net change (4 ) — (4 ) Balance at September 30, 2015 $ 13 $ — $ 13 Foreign currency translation (a) Defined benefit plans (a) Total (dollars in thousands) Balance at December 31, 2013 $ 248 $ 344 $ 592 Net change (233 ) (87 ) (320 ) Balance at September 30, 2014 $ 15 $ 257 $ 272 (a) During the periods presented, the Company did not have material reclassifications out of other comprehensive income.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share, Basic and Diluted	The computation of earnings per share is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (dollars in thousands, except per share data) Net income (loss) $ (6,002 ) $ 10,529 $ 24,048 $ 38,154 Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds 4,344 4,006 10,980 13,409 Net income (loss) attributable to Cowen Group, Inc. (10,346 ) 6,523 13,068 24,745 Preferred stock dividends 1,603 — 2,358 — Net income (loss) attributable to Cowen Group, Inc. common stockholders $ (11,949 ) $ 6,523 $ 10,710 $ 24,745 Shares for basic and diluted calculations: Weighted average shares used in basic computation 109,191 114,969 111,050 115,407 Stock options — — 19 — Performance based restricted stock — — 266 — Stock appreciation rights — 59 152 57 Restricted stock — 3,773 5,762 4,563 Weighted average shares used in diluted computation 109,191 118,801 117,249 120,027 Earnings (loss) per share: Basic $ (0.11 ) $ 0.06 $ 0.10 $ 0.21 Diluted $ (0.11 ) $ 0.05 $ 0.09 $ 0.21

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segment Reporting Information, by Segment	The following tables set forth operating results for the Company's alternative investment and broker dealer segments and related adjustments necessary to reconcile the Company's Economic Income (Loss) measure to arrive at the Company's consolidated US GAAP net income (loss): Three Months Ended September 30, 2015 Adjustments Alternative Broker-Dealer Total Economic Income/(Loss) Funds Other US GAAP (dollars in thousands) Revenues Investment banking $ — $ 53,012 $ 53,012 $ — $ — $ 53,012 Brokerage 18 41,857 41,875 — (790 ) (e) 41,085 Management fees 17,739 282 18,021 (371 ) (7,131 ) (a) 10,519 Incentive income (8,629 ) — (8,629 ) 29 8,693 (a) 93 Investment Income (16,781 ) (5,243 ) (22,024 ) — 22,024 (c) — Interest and dividends — — — — 3,604 (c)(e) 3,604 Reimbursement from affiliates — — — (85 ) 3,440 (f) 3,355 Other revenue (9 ) 573 564 — 748 (c) 1,312 Consolidated Funds revenues — — — 274 — 274 Total revenues (7,662 ) 90,481 82,819 (153 ) 30,588 113,254 Expenses Non interest expense 6,133 84,721 90,854 — 2,112 (c)(d) 92,966 Interest and dividends 2,970 1,287 4,257 — 3,110 (c)(e) 7,367 Consolidated Funds expenses — — — 634 — 634 Total expenses 9,103 86,008 95,111 634 5,222 100,967 Total other income (loss) — — — 554 (23,924 ) (c) (23,370 ) Income taxes expense / (benefit) — — — — (5,081 ) (b) (5,081 ) (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (2,231 ) — (2,231 ) 233 (2,346 ) (4,344 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ (18,996 ) $ 4,473 $ (14,523 ) $ — $ 4,177 $ (10,346 ) Three Months Ended September 30, 2014 Adjustments Alternative Broker-Dealer Total Funds Other US GAAP (dollars in thousands) Revenues Investment banking $ — $ 45,799 $ 45,799 $ — $ — $ 45,799 Brokerage 15 35,568 35,583 — (1,249 ) (e) 34,334 Management fees 16,319 — 16,319 (246 ) (6,277 ) (a) 9,796 Incentive income 4,488 — 4,488 (34 ) (5,291 ) (a) (837 ) Investment Income 4,064 3,399 7,463 — (7,463 ) (c) — Interest and dividends — — — — 13,725 (c)(e) 13,725 Reimbursement from affiliates — — — 119 2,354 (f) 2,473 Other revenue 43 353 396 — 724 (c) 1,120 Consolidated Funds revenues — — — 691 — 691 Total revenues 24,929 85,119 110,048 530 (3,477 ) 107,101 Expenses Non interest expense 21,754 77,050 98,804 — 832 (c)(d) 99,636 Interest and dividends 1,852 812 2,664 — 9,765 (c)(e) 12,429 Consolidated Funds expenses — — — 635 — 635 Total expenses 23,606 77,862 101,468 635 10,597 112,700 Total other income (loss) — — — 888 15,381 (c) 16,269 Income taxes expense / (benefit) — — — — 141 (b) 141 (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (1,877 ) — (1,877 ) (783 ) (1,346 ) (4,006 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ (554 ) $ 7,257 $ 6,703 $ — $ (180 ) $ 6,523 Nine Months Ended September 30, 2015 Adjustments Alternative Investment Broker-Dealer Total Economic Income/(Loss) Funds Consolidation Other Adjustments US GAAP (dollars in thousands) Revenues Investment banking $ — $ 186,763 $ 186,763 $ — $ — $ 186,763 Brokerage 41 112,292 112,333 — (837 ) (e) 111,496 Management fees 50,885 282 51,167 (937 ) (19,061 ) (a) 31,169 Incentive income (1,081 ) — (1,081 ) (278 ) 1,724 (a) 365 Investment Income 14,309 4,763 19,072 — (19,072 ) (c) — Interest and dividends — — — — 9,846 (c)(e) 9,846 Reimbursement from affiliates — — — (261 ) 10,760 (f) 10,499 Other revenue 84 605 689 — 1,995 (c) 2,684 Consolidated Funds revenues — — — 1,134 — 1,134 Total revenues 64,238 304,705 368,943 (342 ) (14,645 ) 353,956 Expenses Non interest expense 57,164 273,939 331,103 — 4,799 (c)(d) 335,902 Interest and dividends 8,880 3,545 12,425 — 6,816 (c)(e) 19,241 Consolidated Funds expenses — — — 1,626 — 1,626 Total expenses 66,044 277,484 343,528 1,626 11,615 356,769 Total other income (loss) — — — 4,278 27,795 (c) 32,073 Income taxes expense / (benefit) — — — — 5,212 (b) 5,212 (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (6,128 ) — (6,128 ) (2,310 ) (2,542 ) (10,980 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ (7,934 ) $ 27,221 $ 19,287 $ — $ (6,219 ) $ 13,068 Nine Months Ended September 30, 2014 Adjustments Alternative Investment Broker-Dealer Total Economic Income/(Loss) Funds Consolidation Other Adjustments US GAAP (dollars in thousands) Revenues Investment banking $ — $ 125,653 $ 125,653 $ — $ — $ 125,653 Brokerage 40 104,943 104,983 — (4,508 ) (e) 100,475 Management fees 46,574 — 46,574 (723 ) (17,439 ) (a) 28,412 Incentive income 16,900 — 16,900 (188 ) (12,327 ) (a) 4,385 Investment Income 29,025 8,207 37,232 — (37,232 ) (c) — Interest and dividends — — — — 35,437 (c)(e) 35,437 Reimbursement from affiliates — — — (45 ) 7,436 (f) 7,391 Other revenue 140 354 494 — 1,933 (c) 2,427 Consolidated Funds revenues — — — 2,500 — 2,500 Total revenues 92,679 239,157 331,836 1,544 (26,700 ) 306,680 Expenses Non interest expense 71,421 220,913 292,334 — 3,269 (c)(d) 295,603 Interest and dividends 5,083 878 5,961 — 23,733 (c)(e) 29,694 Consolidated Funds expenses — — — 1,335 — 1,335 Total expenses 76,504 221,791 298,295 1,335 27,002 326,632 Total other income (loss) — — — 3,509 54,863 (c) 58,372 Income taxes expense / (benefit) — — — — 266 (b) 266 (Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds (8,320 ) — (8,320 ) (3,718 ) (1,371 ) (13,409 ) Economic Income (Loss) / Net Income (loss) attributable to Cowen Group, Inc. $ 7,855 $ 17,366 $ 25,221 $ — $ (476 ) $ 24,745 The following is a summary of the adjustments made to US GAAP net income (loss) for the segment to arrive at Economic Income (Loss): Funds Consolidation: The impacts of consolidation and the related elimination entries of the Consolidated Funds are not included in Economic Income (Loss). Adjustments to reconcile to US GAAP net income (loss) include elimination of incentive income and management fees earned from the Consolidated Funds and addition of fund expenses excluding management fees paid, fund revenues and investment income (loss). Other Adjustments: (a) Economic Income (Loss) recognizes revenues (i) net of distribution fees paid to agents and (ii) our proportionate share of management and incentive fees of certain real estate operating entities and the activist business. (b) Economic Income (Loss) excludes income taxes as management does not consider this item when evaluating the performance of the segment. (c) Economic Income (Loss) recognizes Company income from proprietary trading (including interest and dividends) net of related expenses. (d) Economic Income (Loss) recognizes the Company's proportionate share of expenses for certain real estate and other operating entities for which the investments are recorded under the equity method of accounting for investments. (e) Economic Income (Loss) recognizes stock borrow/loan activity (prior to January 2015) and other brokerage dividends as brokerage revenue. (f) Reimbursement from affiliates is shown as a reduction of Economic Income expenses, but is included as a part of revenues under US GAAP.

Organization and Business (Deta

Organization and Business (Details)	9 Months Ended
	Sep. 30, 2015segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of business segments	2

Acquisition (Details)

Acquisition (Details) - USD ($)	1 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 01, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	$ 0	$ 0			$ 900,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	6,700,000	6,700,000			$ 7,100,000
Concept (Cowen Prime)
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	0	0
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	6,700,000	6,700,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets				$ 25,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents				1,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equipment				600,000
Intangible Assets, Net (Including Goodwill)				17,800,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets				5,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				2,600,000
Business Acquisition, Transaction Costs				$ 600,000
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	2,200,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	$ 100,000
Revenues		375,651,000	$ 328,677,000
Net income (loss) attributable to Cowen Group, Inc. common stockholders		$ 12,952,000	$ 24,840,000
Net income per common share - Basic (in dollars per share)		$ 0.12	$ 0.21
Net income per common share - Diluted (in dollars per share)		$ 0.11	$ 0.21

Significant Accounting Polici45

Significant Accounting Policies All Other - Quarterly (Details) $ in Thousands	Sep. 30, 2015USD ($)cowenfund	Dec. 31, 2014USD ($)cowenfund
Redeemable Noncontrolling Interest [Line Items]
Total net assets of consolidated VIEs | $	$ 1,000	$ 2,000
Deferred rent | $	$ 12,242	$ 13,142
Variable Interest Entity, Primary Beneficiary [Member]
Redeemable Noncontrolling Interest [Line Items]
Number of funds, Consolidated	3	2
Other investment companies
Redeemable Noncontrolling Interest [Line Items]
Number of funds, Consolidated	3	3
Investment Company
Redeemable Noncontrolling Interest [Line Items]
Number of funds, Consolidated	4	4

Cash Collateral Pledged (Detail

Cash Collateral Pledged (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Cash collateral pledged	$ 9,129	$ 8,306

Investments of Operating Enti47

Investments of Operating Entities and Consolidated Funds - Securities Owned at Fair Value - Quarterly (Details) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Investment Holdings [Line Items]
Fair Value, Concentration of Risk, Investments		$ 0	$ 0
Marketable Securities, Consolidated Funds		19,000,000	0
Securities owned, at fair value		$ 864,685,000	$ 792,206,000
US Government Securities | Minimum
Investment Holdings [Line Items]
Debt securities, interest rate		0.00%	0.00%
US Government Securities | Maximum
Investment Holdings [Line Items]
Debt securities, interest rate		5.95%	5.95%
Preferred Stock
Investment Holdings [Line Items]
Trading Securities, Equity		$ 15,771,000	$ 15,070,000
Common Stock
Investment Holdings [Line Items]
Trading Securities, Equity		712,489,000	597,476,000
Convertible Bonds
Investment Holdings [Line Items]
Trading Securities, Debt	[1]	$ 1,129,000	$ 900,000
Debt securities, interest rate			10.00%
Convertible Bonds | Minimum
Investment Holdings [Line Items]
Debt securities, interest rate		8.00%
Convertible Bonds | Maximum
Investment Holdings [Line Items]
Debt securities, interest rate		10.00%
Corporate Bonds
Investment Holdings [Line Items]
Trading Securities, Debt	[2]	$ 113,585,000	$ 159,557,000
Corporate Bonds | Minimum
Investment Holdings [Line Items]
Debt securities, interest rate		3.17%	5.63%
Corporate Bonds | Maximum
Investment Holdings [Line Items]
Debt securities, interest rate		21.74%	11.54%
US Treasury and Government
Investment Holdings [Line Items]
Trading Securities, Debt	[3]	$ 3,015,000	$ 2,010,000
Warrants and Rights
Investment Holdings [Line Items]
Trading Securities, Equity		3,871,000	1,417,000
Mutual Funds
Investment Holdings [Line Items]
Trading Securities, Equity		14,825,000	15,776,000
Enterprise Master
Investment Holdings [Line Items]
Securities owned, at fair value		5,250,000	5,896,000
Enterprise Master | Debt
Investment Holdings [Line Items]
Securities owned, at fair value		0	20,000
Enterprise Master | Trade Claims
Investment Holdings [Line Items]
Securities owned, at fair value		128,000	128,000
Enterprise Master | Preferred Stock
Investment Holdings [Line Items]
Securities owned, at fair value		626,000	576,000
Enterprise Master | Private Equity
Investment Holdings [Line Items]
Securities owned, at fair value		0	587,000
Enterprise Master | Common Stock
Investment Holdings [Line Items]
Securities owned, at fair value		1,657,000	1,659,000
Enterprise Master | Restricted Stock
Investment Holdings [Line Items]
Securities owned, at fair value		124,000	124,000
Enterprise Master | Rights
Investment Holdings [Line Items]
Securities owned, at fair value		2,715,000	2,802,000
Merger Master
Investment Holdings [Line Items]
Securities owned, at fair value		179,650,000	136,893,000
Merger Master | Common Stock
Investment Holdings [Line Items]
Securities owned, at fair value		179,650,000	133,510,000
Merger Master | Corporate Bonds
Investment Holdings [Line Items]
Securities owned, at fair value	[4]	0	$ 3,383,000
Merger Master | Corporate Bonds | Minimum
Investment Holdings [Line Items]
Debt securities, interest rate			8.50%
Merger Master | Corporate Bonds | Maximum
Investment Holdings [Line Items]
Debt securities, interest rate			9.75%
Quadratic Master
Investment Holdings [Line Items]
Securities owned, at fair value		15,267,000
Quadratic Master | Common Stock
Investment Holdings [Line Items]
Securities owned, at fair value		267,000
Quadratic Master | US Treasury and Government
Investment Holdings [Line Items]
Securities owned, at fair value	[5]	$ 15,000,000
Debt securities, interest rate		0.00%
[1]	As of September 30, 2015, maturities ranged from July 2016 to March 2018 with interest rates ranged between 8% to 10.00%. As of December 31, 2014, the maturity was February 2015 with an interest rate of 10.00%.
[2]	As of September 30, 2015, maturities ranged from March 2016 to February 2046 and interest rates ranged between 3.17% to 21.74%. As of December 31, 2014, maturities ranged from February 2015 to February 2046 and interest rates ranged between 5.63% to 11.54%.
[3]	As of September 30, 2015, maturities ranged from December 2015 to August 2016 with interest rates ranged between 0% to 5.95%. As of December 31, 2014, maturities ranged from May 2015 to April 2016 with interest rates ranged between 0% to 5.95%.
[4]	As of December 31, 2014, maturities ranged from February 2017 to June 2019 and interest rates ranged between 8.50% and 9.75%.
[5]	As of September 30, 2015, the maturity was October 2015 with an interest rate of 0%.

Investments of Operating Enti48

Investments of Operating Entities and Consolidated Funds - Derivatives (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015USD ($)contractshares	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)contractshares	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)contract	Mar. 10, 2014USD ($)$ / shares
Derivative [Line Items]
Securities sold, not yet purchased, at fair value		$ 250,739		$ 250,739		$ 207,875
Warrants issued					$ 15,218
Cost of hedge transaction and warrant, net							$ 20,500
Receivable on derivative contracts, at fair value		41,587		41,587		49,877
Payable for derivative contracts, at fair value		26,078		$ 26,078		41,330
Trading days for expiration				80 days
Futures
Derivative [Line Items]
Receivable on derivative contracts, at fair value		68		$ 68		75
Payable for derivative contracts, at fair value		381		381		33
Derivative Asset, Notional Amount		4,679		4,679		3,041
Derivative Liability, Notional Amount		32,423		32,423		2,213
Currency Forwards
Derivative [Line Items]
Receivable on derivative contracts, at fair value		105		105		310
Payable for derivative contracts, at fair value		107		107		0
Derivative Asset, Notional Amount		34,036		34,036		23,961
Derivative Liability, Notional Amount		43,788		43,788		0
Equity Swaps
Derivative [Line Items]
Receivable on derivative contracts, at fair value		470		470		251
Payable for derivative contracts, at fair value		2,615		2,615		1,603
Derivative Asset, Notional Amount		52,000		52,000		12,904
Derivative Liability, Notional Amount		45,193		45,193		18,352
Options
Derivative [Line Items]
Receivable on derivative contracts, at fair value	[1]	$ 34,498		$ 34,498		$ 48,201
Derivative Asset, Number of Instruments Held | contract	[1]	306,659		306,659		367,441
Put Option
Derivative [Line Items]
Payable for derivative contracts, at fair value	[2]	$ 22,975		$ 22,975		$ 39,694
Derivative Liability, Number of Instruments Held | contract	[2]	14,035		14,035		22,043
Foreign Exchange Option
Derivative [Line Items]
Receivable on derivative contracts, at fair value		$ 6,446		$ 6,446		$ 1,040
Derivative Asset, Notional Amount		292,475		292,475		32,200
Receivables from Brokers-Dealers and Clearing Organizations
Derivative [Line Items]
Collateral posted		20,900		20,900		5,500
Other Income
Derivative [Line Items]
Realized and unrealized gains/(losses) related to derivatives trading activities		(200)	$ 5,100	(5,600)	$ 1,400
Enterprise Master
Derivative [Line Items]
Receivable on derivative contracts, at fair value		(4)		(4)		64
Merger Master
Derivative [Line Items]
Receivable on derivative contracts, at fair value		776		776		617
Payable for derivative contracts, at fair value		4,699		4,699		294
Merger Master | Exchange Traded Funds
Derivative [Line Items]
Payable for derivative contracts, at fair value		3,801		3,801		0
Merger Master | Equity Swaps
Derivative [Line Items]
Payable for derivative contracts, at fair value		862		862		56
Merger Master | Put Option
Derivative [Line Items]
Payable for derivative contracts, at fair value		36		36		238
Quadratic Master
Derivative [Line Items]
Receivable on derivative contracts, at fair value		$ 9,654		$ 9,654
Common Stock Class A
Derivative [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares		28,048,786		28,048,786
Class of Warrant, Exercise Price of Warrants or Rights | $ / shares							$ 7.18
Convertible Debt
Derivative [Line Items]
Call Option, Fair Value		$ 21,600		$ 21,600			$ 35,700
Receivable on derivatives contracts, at fair value [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		41,587		41,587		49,877
Receivable on derivative contracts, at fair value		41,587		41,587		49,877
Derivative Asset, Fair Value, Amount Offset Against Collateral	[3]	0		0		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	[4]	8,950		8,950		2,588
Derivative asset, net of offset		32,637		32,637		47,289
Financial Instruments, Owned and Pledged as Collateral, at Fair Value		0		0		0
Payable for derivatives contracts, at fair value [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability		26,078		26,078		41,330
Payable for derivative contracts, at fair value		26,078		26,078		41,330
Financial Instruments, Owned and Pledged as Collateral, at Fair Value		0		0		0
Derivative Liability, Fair Value, Amount Offset Against Collateral	[3]	0		0		0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	[4]	2,643		2,643		1,603
Derivative Liability, net of offset		23,435		23,435		39,727
Currency forward | Quadratic Master
Derivative [Line Items]
Receivable on derivative contracts, at fair value		32		32
Options | Quadratic Master
Derivative [Line Items]
Receivable on derivative contracts, at fair value		9,622		9,622
Put Option | Quadratic Master
Derivative [Line Items]
Payable for derivative contracts, at fair value		100		100
Currency Forwards | Enterprise Master
Derivative [Line Items]
Receivable on derivative contracts, at fair value		$ (4)		$ (4)		$ 64
[1]	Includes index, equity, commodity future and cash conversion options.
[2]	Includes index, equity, commodity future and cash conversion options.
[3]	Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred.
[4]	Includes the amount of collateral held or posted.

Investments of Operating Enti49

Investments of Operating Entities and Consolidated Funds - Other Investments - Quarterly (Details) - USD ($) $ in Thousands		Sep. 30, 2015		Dec. 31, 2014
Investment Holdings [Line Items]
Other Investments, Consolidated Funds		$ 255,896		$ 189,377
Other investments		153,334		167,464
Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other Investments, Consolidated Funds		255,896	[1]	188,884	[2]
Other investments		108,509	[1]	103,466	[2]
Real Estate Equity Investment
Investment Holdings [Line Items]
Other investments		1,916		2,175
Equity Method Investments
Investment Holdings [Line Items]
Other investments		42,574		61,443
Lehman claims, at fair value
Investment Holdings [Line Items]
Other Investments, Consolidated Funds		0		493
Other investments		335		380
Healthcare Royalty Partners | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[3],[4]	12,016		11,935
Healthcare Royalty Partners II | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[3],[4]	7,439		6,648
Orchard Square Partners Credit Fund LP | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[5]	4,473		11,532
Starboard Value and Opportunity Fund LP | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[6]	20,914		21,792
Starboard Partners Fund LP | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[7]	13,785		14,652
Starboard Leaders Fund LP | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[8]	1,251		1,367
Formation 8 Partners Fund I LP | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[9]	17,364		11,283
Formation 8 Partners Hardware Fund I, L.P. | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[10]	1,125		0
RCG LV Park Lane LLC | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[11]	1,364		642
RCGL 12E13th LLC | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[12]	632		638
RCGLongview Debt Fund V, L.P. | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[12]	14,745		12,876
RCG LPP SME Co-Invest, L.P. | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[13]	2,469		0
Other Funds | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[14]	6,591		7,324
Other Funds | Affiliated Entity | Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	[4],[15]	$ 4,341		$ 2,777
[1]	In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.
[2]	In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.
[3]	HealthCare Royalty Partners, L.P. and HealthCare Royalty Partners II, L.P. are private equity funds and therefore distributions will be made when cash flows are received from the underlying investments, typically on a quarterly basis.
[4]	These portfolio funds are affiliates of the Company.
[5]	Orchard Square Partners Credit Fund LP has a quarterly redemption policy with a 60 day notice period and a 4% penalty on redemptions of investments of less than a year in duration.
[6]	Starboard Value and Opportunity Fund LP permits quarterly withdrawals upon 90 days notice.
[7]	Starboard Partners Fund LP permits redemptions on a semi-annual basis on 180 days prior written notice subsequent to an initial two year lock up.
[8]	Starboard Leaders Fund LP does not permit withdrawals, but instead allows terminations with respect to capital commitments upon 30 days prior written notice at any time following the first anniversary of an investors initial capital contribution.
[9]	Formation8 Partners Fund I, L.P. is a private equity fund which invests in early stage and growth transformational information and energy technology companies. Distributions will be made when the underlying investments are liquidated.
[10]	Formation8 Partners Hardware Fund I, L.P. is a private equity fund which invests in early stage and growth hardware companies. Distributions will be made when the underlying investments are liquidated.
[11]	RCG LV Park Lane LLC is a single purpose entity formed to participate in a joint venture which acquired, at a discount, the mortgage notes on a portfolio of multifamily real estate properties located in Birmingham, Alabama. RCG LV Park Lane LLC is a private equity structure and therefore distributions will be made when the underlying investments are liquidated.
[12]	RCGL 12E13th LLC and RCG Longview Debt Fund V, L.P. are real estate private equity structures and therefore distributions will be made when the underlying investments are liquidated.
[13]	RCG LPP SME Co-Invest, L.P. is a single purpose entity formed to participate in a joint venture which acquired two fully entitled residential development sites in the New York City metro area. RCG LPP SME Co-Invest, L.P. is a private equity structure and therefore distributions will be made when the underlying investments are liquidated.
[14]	Other private investment represents the Company's closed end investment in a portfolio fund that invests in a wireless broadband communication provider in Italy.
[15]	The majority of these funds are affiliates of the Company or are managed by the Company and the investors can redeem from these funds as investments are liquidated.

Investments of Operating Enti50

Investments of Operating Entities and Consolidated Funds - Portfolio Funds - Quarterly (Details) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds		$ 255,896			$ 188,884
Other investments		153,334			167,464
Enterprise LP
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds		122,858			138,253
Merger Fund
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds		60,432			50,631
Quadratic Fund LLC
Investment Holdings [Line Items]
Portfolio Funds, Consolidated Funds		72,606			0
Portfolio Funds
Investment Holdings [Line Items]
Other investments		108,509	[1]		103,466	[2]
Portfolio Funds | Healthcare Royalty Partners | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[3],[4]	12,016			11,935
Portfolio Funds | Healthcare Royalty Partners II | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[3],[4]	7,439			6,648
Portfolio Funds | Orchard Square Partners Credit Fund LP
Investment Holdings [Line Items]
Other investments	[5]	$ 4,473			11,532
Portfolio Funds | Orchard Square Partners Credit Fund LP | Affiliated Entity
Investment Holdings [Line Items]
Required notice period, redemption		60 days		60 days
Penalty on redemptions of less than one year		4.00%		4.00%
Portfolio Funds | Starboard Value and Opportunity Fund LP | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[6]	$ 20,914			21,792
Required notice period, withdrawal		90 days		90 days
Portfolio Funds | Starboard Partners Fund LP | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[7]	$ 13,785			14,652
Portfolio Funds | Starboard Leaders Fund LP | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[8]	$ 1,251			1,367
Unfunded Commitment cancellation		30 days		30 days
Portfolio Funds | Formation 8 Partners Fund I LP
Investment Holdings [Line Items]
Other investments	[9]	$ 17,364			11,283
Portfolio Funds | RCG LV Park Lane LLC | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[10]	1,364			642
Portfolio Funds | RCGL 12E13th LLC | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[11]	632			638
Portfolio Funds | RCGLongview Debt Fund V, L.P. | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[11]	14,745			12,876
Portfolio Funds | Other Funds
Investment Holdings [Line Items]
Other investments	[12]	6,591			7,324
Portfolio Funds | Other Funds | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[13]	4,341			2,777
Portfolio Funds | RCG LPP SME Co-Invest, L.P. | Affiliated Entity
Investment Holdings [Line Items]
Other investments	[4],[14]	2,469			0
Portfolio Funds | Enterprise Master
Investment Holdings [Line Items]
Other investments		121,803			135,846
Portfolio Funds | Enterprise Master | RCG Longview Equity Fund, LP | Affiliated Entity | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	7,637			9,090
Portfolio Funds | Enterprise Master | RCG Longview II, LP | Affiliated Entity | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	785			747
Portfolio Funds | Enterprise Master | RCG Longview Debt Fund IV, LP | Affiliated Entity | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	3,999			5,348
Portfolio Funds | Enterprise Master | RCG Longview, LP | Affiliated Entity | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	0			40
Portfolio Funds | Enterprise Master | RCG Soundview, LLC | Affiliated Entity | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	452			452
Portfolio Funds | Enterprise Master | RCG Urban American Real Estate Fund, L.P. | Affiliated Entity | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	648			1,161
Portfolio Funds | Enterprise Master | RCG International Sarl | Affiliated Entity | Multi-strategy
Investment Holdings [Line Items]
Other investments	[15]	1,220			2,113
Portfolio Funds | Enterprise Master | RCG Special Opportunities Fund, Ltd | Affiliated Entity | Multi-strategy
Investment Holdings [Line Items]
Other investments	[15]	89,303			92,405
Portfolio Funds | Enterprise Master | RCG Energy, LLC | Affiliated Entity | Energy Strategy
Investment Holdings [Line Items]
Other investments	[15]	1,398			2,294
Portfolio Funds | Enterprise Master | RCG Renergys, LLC | Affiliated Entity | Energy Strategy
Investment Holdings [Line Items]
Other investments	[15]	1			1
Portfolio Funds | Enterprise Master | Other Private Investment | Various Strategies
Investment Holdings [Line Items]
Other investments		10,629			12,057
Portfolio Funds | Enterprise Master | Real Estate Funds | Real Estate Strategy
Investment Holdings [Line Items]
Other investments	[15]	$ 5,731			$ 10,138
[1]	In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.
[2]	In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.
[3]	HealthCare Royalty Partners, L.P. and HealthCare Royalty Partners II, L.P. are private equity funds and therefore distributions will be made when cash flows are received from the underlying investments, typically on a quarterly basis.
[4]	These portfolio funds are affiliates of the Company.
[5]	Orchard Square Partners Credit Fund LP has a quarterly redemption policy with a 60 day notice period and a 4% penalty on redemptions of investments of less than a year in duration.
[6]	Starboard Value and Opportunity Fund LP permits quarterly withdrawals upon 90 days notice.
[7]	Starboard Partners Fund LP permits redemptions on a semi-annual basis on 180 days prior written notice subsequent to an initial two year lock up.
[8]	Starboard Leaders Fund LP does not permit withdrawals, but instead allows terminations with respect to capital commitments upon 30 days prior written notice at any time following the first anniversary of an investors initial capital contribution.
[9]	Formation8 Partners Fund I, L.P. is a private equity fund which invests in early stage and growth transformational information and energy technology companies. Distributions will be made when the underlying investments are liquidated.
[10]	RCG LV Park Lane LLC is a single purpose entity formed to participate in a joint venture which acquired, at a discount, the mortgage notes on a portfolio of multifamily real estate properties located in Birmingham, Alabama. RCG LV Park Lane LLC is a private equity structure and therefore distributions will be made when the underlying investments are liquidated.
[11]	RCGL 12E13th LLC and RCG Longview Debt Fund V, L.P. are real estate private equity structures and therefore distributions will be made when the underlying investments are liquidated.
[12]	Other private investment represents the Company's closed end investment in a portfolio fund that invests in a wireless broadband communication provider in Italy.
[13]	The majority of these funds are affiliates of the Company or are managed by the Company and the investors can redeem from these funds as investments are liquidated.
[14]	RCG LPP SME Co-Invest, L.P. is a single purpose entity formed to participate in a joint venture which acquired two fully entitled residential development sites in the New York City metro area. RCG LPP SME Co-Invest, L.P. is a private equity structure and therefore distributions will be made when the underlying investments are liquidated.
[15]	Affiliates of the Company.

Investments of Operating Enti51

Investments of Operating Entities and Consolidated Funds - Real Estate (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Other investments	$ 153,334	$ 167,464
Real Estate Equity Investment
Other investments	1,916	2,175
Real Estate Equity Investment | RCG RE Manager, LLC
Other investments	1,900	2,200
Clawback Obligation
Other Commitment	6,200	6,200
Clawback Obligation | RCG Longview Partners II, LLC
Other Commitment	$ 6,200	$ 6,200

Investments of Operating Enti52

Investments of Operating Entities and Consolidated Funds - Equity Method Investments - Quarterly (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Other investments	$ 153,334		$ 153,334		$ 167,464
Net Gains (Losses) on Securities, Derivatives and Other Investments
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments	(5,900)	$ 7,200	3,400	$ 17,500
Clawback Obligation
Schedule of Equity Method Investments [Line Items]
Other Commitment	6,200		6,200		6,200
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	42,574		42,574		61,443
Equity Method Investee, Exceeded Threshold for Income Test
Schedule of Equity Method Investments [Line Items]
Revenues	(3,216)	13,258	8,249	21,956
Expenses	(2,033)	(7,772)	(1,927)	(5,349)
Net realized and unrealized gains (losses)	(155)	(40)	51	165
Net Income	(5,404)	$ 5,446	6,373	$ 16,772
RCG Longview Debt Fund IV Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	464		464		676
RCG Longview Debt Fund V Partners, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	3,988		3,988		2,684
Healthcare Royalty GP, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	980		980		973
Healthcare Royalty GP II, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	1,260		1,260		1,125
Healthcare Royalty GP III, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	$ 71		$ 71		62
CBOE Stock Exchange, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	7.20%		7.20%
CBOE Stock Exchange, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	$ 568		$ 568		611
Starboard Value LP | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	30,079		30,079		48,772
RCG Longview Partners, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	0		0		237
RCG Longview Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	1,287		1,287		1,117
RCG Urban American, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	122		122		422
RCG Urban American Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	379		379		379
RCG Longview Equity Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	250		250		316
Urban American Real Estate Fund II, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	1,975		1,975		2,329
RCG Kennedy House, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	268		268		509
Equity Method Investee, Other | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	883		883		1,231
RCG Longview Partners II, LLC | Clawback Obligation
Schedule of Equity Method Investments [Line Items]
Other Commitment	$ 6,200		$ 6,200		$ 6,200
Minimum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%		20.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	55.00%		55.00%

Investments of Operating Enti53

Investments of Operating Entities and Consolidated Funds - Lehman Claims (Details) - Lehman claims, at fair value - USD ($) $ in Millions	Sep. 30, 2015	Sep. 15, 2008
Investment Holdings [Line Items]
Initial value		$ 1
Total Dividend Amount Received	$ 1
Total Dividend percent received	100.00%
Enterprise Master
Investment Holdings [Line Items]
Initial value		$ 24.3
Total Dividend Amount Received	$ 37.2

Investments of Operating Enti54

Investments of Operating Entities and Consolidated Funds - Securities Sold, Not Yet Purchased (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Investments Sold, Not yet Purchased [Line Items]
Receivable on derivative contracts, at fair value		$ 41,587	$ 49,877
Securities owned, at fair value		864,685	792,206
Securities sold, not yet purchased, at fair value		250,739	207,875
Merger Master
Investments Sold, Not yet Purchased [Line Items]
Receivable on derivative contracts, at fair value		776	617
Securities owned, at fair value		179,650	136,893
Corporate Bonds
Investments Sold, Not yet Purchased [Line Items]
Securities sold, not yet purchased, at fair value	[1]	$ 59	$ 60
Securities sold, not yet purchased, interest rate		5.55%	5.55%
Common Stock
Investments Sold, Not yet Purchased [Line Items]
Securities sold, not yet purchased, at fair value		$ 250,680	$ 207,815
Common Stock | Merger Master
Investments Sold, Not yet Purchased [Line Items]
Securities sold, not yet purchased, at fair value		57,700	39,900
Currency forward | Merger Master
Investments Sold, Not yet Purchased [Line Items]
Receivable on derivative contracts, at fair value		22	0
Options | Merger Master
Investments Sold, Not yet Purchased [Line Items]
Receivable on derivative contracts, at fair value		604	541
Equity Swaps | Merger Master
Investments Sold, Not yet Purchased [Line Items]
Receivable on derivative contracts, at fair value		$ 150	$ 76
[1]	As of September 30, 2015 and December 31, 2014, the maturity was January 2026 with an interest rate of 5.55%

Investments of Operating Enti55

Investments of Operating Entities and Consolidated Funds - Securities Lending and Borrowing Transactions (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Securities borrowed		$ 0	$ 676,100
Securities Borrowed, Amount Offset Against Collateral	[1]		0
Securities Borrowed			676,100
Securities Borrowed, Not Offset, Policy Election Deduction			(15,655)
Securities Borrowed, Not Offset against Collateral	[2]		0
Securities Borrowed, net			0
Securities loaned		$ 0	682,493
Securities Loaned, Amount Offset Against Collateral	[1]		0
Securities Loaned			682,493
Securities Loaned, Not Offset, Policy Election Deduction			(2,441)
Securities Loaned, Fair Value of Collateral	[2]		0
Securities Loaned, Not Offset Against Collateral			0
securities borrowed [Member]
Financial Instruments, Owned and Pledged as Collateral, at Fair Value			(660,445)
securities loaned [Member]
Financial Instruments, Owned and Pledged as Collateral, at Fair Value			$ (680,052)
[1]	Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred.
[2]	Includes the amount of cash collateral held/posted.

Investments of Operating Enti56

Investments of Operating Entities and Consolidated Funds - Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Total assets of nonconsolidated variable interest entities	$ 3,200	$ 3,000
Total liabilities of nonconsolidated variable interest entities	415.6	499.2
Maximum exposure regarding nonconsolidated variable interest entities	$ 314.6	$ 260.9

Fair Value Measurements for O57

Fair Value Measurements for Operating Entities and Consolidated Funds Assets and Liabilities at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2015		Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	$ 927,523		$ 845,131
Financial Liabilities Fair Value Disclosure	282,275		253,288
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	0		900
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	6,700		7,100
Other investments	153,334		167,464
Other Investments, Consolidated Funds	255,896		189,377
Investments	1,334,502		1,198,924
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	718,314		607,352
Financial Liabilities Fair Value Disclosure	252,445		210,735
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	146,156		182,773
Financial Liabilities Fair Value Disclosure	2,781		1,663
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	63,053		55,006
Financial Liabilities Fair Value Disclosure	27,049		40,890
Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	250,680		207,815
Common Stock | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	250,680		207,815
Common Stock | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Common Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	59		60
Corporate Bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Corporate Bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	59		60
Corporate Bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Contingent liability payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	5,458	[1]	4,083	[2]
Contingent liability payable | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0	[1]	0	[2]
Contingent liability payable | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0	[1]	0	[2]
Contingent liability payable | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	5,458	[1]	4,083	[2]
Futures | Derivative Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	381		33
Futures | Derivative Liabilities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	381		33
Futures | Derivative Liabilities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Futures | Derivative Liabilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Currency forward | Derivative Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	$ 107
Currency forward | Derivative Liabilities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure
Currency forward | Derivative Liabilities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	$ 107
Currency forward | Derivative Liabilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0
Equity Swaps | Derivative Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	$ 2,615		1,603
Equity Swaps | Derivative Liabilities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure			0
Equity Swaps | Derivative Liabilities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	$ 2,615		1,603
Equity Swaps | Derivative Liabilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Put Option | Derivative Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	22,975		39,694
Put Option | Derivative Liabilities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	1,384		2,887
Put Option | Derivative Liabilities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	0		0
Put Option | Derivative Liabilities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	21,591		36,807
US Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	3,015		2,010
US Government Securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	3,015		2,010
US Government Securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
US Government Securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Preferred Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	15,771		15,070
Preferred Stock | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Preferred Stock | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		2,553
Preferred Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	15,771		12,517
Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	712,489		597,476
Common Stock | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	689,252		578,934
Common Stock | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	22,920		18,130
Common Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	317		412
Convertible Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	1,129		900
Convertible Bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Convertible Bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Convertible Bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	1,129		900
Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	113,585		159,557
Corporate Bonds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Corporate Bonds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	113,585		159,557
Corporate Bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Warrants and Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	3,871		1,417
Warrants and Rights | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	877		95
Warrants and Rights | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Warrants and Rights | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	2,994		1,322
Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	14,825		15,776
Mutual Funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	14,825		15,776
Mutual Funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Mutual Funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	68		75
Derivative Assets | Futures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	68		75
Derivative Assets | Futures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Futures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Currency forward
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	105		310
Derivative Assets | Currency forward | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Currency forward | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	105		310
Derivative Assets | Currency forward | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Equity Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	470		251
Derivative Assets | Equity Swaps | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Equity Swaps | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	470		251
Derivative Assets | Equity Swaps | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Derivative Assets | Options
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	40,944		49,241
Derivative Assets | Options | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	10,277		10,462
Derivative Assets | Options | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	9,076		1,972
Derivative Assets | Options | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	21,591		36,807
Portfolio Funds, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	108,509	[3]	103,466	[4]
Other Investments, Consolidated Funds	255,896	[3]	188,884	[4]
Real Estate Investments, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	1,916		2,175
Real Estate Investments, at fair value | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Real Estate Investments, at fair value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Real Estate Investments, at fair value | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	1,916		2,175
Lehman claims, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	335		380
Other investments	335		380
Other Investments, Consolidated Funds	0		493
Lehman claims, at fair value | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Lehman claims, at fair value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Lehman claims, at fair value | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	335		380
Equity Method Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	42,574		61,443
Consolidated Funds | Preferred Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	19,000
Consolidated Funds | Preferred Stock | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0
Consolidated Funds | Preferred Stock | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0
Consolidated Funds | Preferred Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	$ 19,000
Consolidated Funds | Lehman claims, at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring			493
Consolidated Funds | Lehman claims, at fair value | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring			0
Consolidated Funds | Lehman claims, at fair value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring			0
Consolidated Funds | Lehman claims, at fair value | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring			$ 493
[1]	In accordance with the terms of the purchase agreements for acquisitions that closed during 2012 and the third quarter of 2015, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the periods ended August 2016 and December 2020, respectively. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts as of September 30, 2015 can range from zero to $6.7 million.
[2]	In accordance with the terms of a purchase agreement for an acquisitions that closed during 2012, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the period ended August 2016. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts can range from $0.9 million to $7.1 million.
[3]	In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.
[4]	In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.

Fair Value Measurements for O58

Fair Value Measurements for Operating Entities and Consolidated Funds Unobservable Input Roll Forward (Details) - USD ($)		3 Months Ended			9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value					$ 55,006,000
Balance Liability Value					40,890,000
Balance Asset Value		$ 63,053,000			63,053,000
Balance Liability Value		27,049,000			27,049,000
Fair value, Between Level 1 and 2 transfers, amount		0			0
Preferred Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		23,462,000		$ 2,574,000	12,517,000		$ 324,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out	[1]	(9,000,000)	[2]	(2,000,000)	(15,823,000)	[2]	(2,000,000)
Purchases/(covers)		3,500,000		0	21,750,000		2,250,000
(Sales)/short buys		(6,665,000)		0	(6,665,000)		0
Realized and unrealized gains (losses), asset		4,474,000		0	3,992,000		0
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	1,200,000		0	717,000		0
Balance Asset Value		15,771,000		574,000	15,771,000		574,000
Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		404,000		419,000	412,000		3,559,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		(3,150,000)	[1]
Purchases/(covers)		104,000		0	104,000		9,000
(Sales)/short buys		(89,000)		(1,000)	(120,000)		(1,000)
Realized and unrealized gains (losses), asset		(102,000)		(128,000)	(79,000)		(127,000)
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	(87,000)		(14,000)	(74,000)		(13,000)
Balance Asset Value		317,000		290,000	317,000		290,000
Convertible Bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		879,000		1,750,000	900,000		1,950,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		0
Purchases/(covers)		250,000		0	250,000		0
(Sales)/short buys		0		0	0		(200,000)
Realized and unrealized gains (losses), asset		0		0	(21,000)		0
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	0		0	(21,000)		0
Balance Asset Value		1,129,000		1,750,000	1,129,000		1,750,000
Options
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		58,576,000		37,658,000	36,807,000		0
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		0
Purchases/(covers)		0		0	0		35,710,000
(Sales)/short buys		0		0	0		0
Realized and unrealized gains (losses), asset		(36,985,000)		(8,873,000)	(15,216,000)		(6,925,000)
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	(36,985,000)		(8,873,000)	(15,216,000)		(6,925,000)
Balance Asset Value		21,591,000		28,785,000	21,591,000		28,785,000
Warrants and Rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		2,316,000		3,346,000	1,322,000		5,805,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		0
Purchases/(covers)		0		57,000	26,000		57,000
(Sales)/short buys		0		(57,000)	(71,000)		(1,385,000)
Realized and unrealized gains (losses), asset		678,000		(738,000)	1,717,000		(1,869,000)
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	878,000		(434,000)	1,757,000		(432,000)
Balance Asset Value		2,994,000		2,608,000	2,994,000		2,608,000
Real Estate Investments, at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		1,987,000		2,262,000	2,175,000		2,088,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		0
Purchases/(covers)		0		0	0		50,000,000
(Sales)/short buys		(70,000)		0	(377,000)		(50,027,000)
Realized and unrealized gains (losses), asset		(1,000)		23,000	118,000		224,000
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	(1,000)		23,000	118,000		224,000
Balance Asset Value		1,916,000		2,285,000	1,916,000		2,285,000
Lehman claims, at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		347,000		418,000	380,000		378,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		0
Purchases/(covers)		0		0	0		0
(Sales)/short buys		0		0	0		(76,000)
Realized and unrealized gains (losses), asset		(12,000)		(58,000)	(45,000)		58,000
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	(12,000)		(58,000)	(45,000)		58,000
Balance Asset Value		335,000		360,000	335,000		360,000
Consolidated Funds | Preferred Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		0			0
Asset, Transfers In		0			0
Asset, Transfers Out	[2]	(7,000,000)			7,000,000
Purchases/(covers)		12,000,000			12,000,000
(Sales)/short buys		0			0
Realized and unrealized gains (losses), asset		0			0
Change in Unrealized Gain (Loss), instruments still held, asset		0			0	[3]
Balance Asset Value		19,000,000			19,000,000
Consolidated Funds | Lehman claims, at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		744,000		4,090,000	493,000		4,842,000
Asset, Transfers In		0		0	0		0
Asset, Transfers Out		0		0	0		0
Purchases/(covers)		0		0	0		0
(Sales)/short buys		(739,000)		(3,731,000)	(739,000)		(4,711,000)
Realized and unrealized gains (losses), asset		(5,000)		2,000	246,000		230,000
Change in Unrealized Gain (Loss), instruments still held, asset	[3]	0		2,000	0		230,000
Balance Asset Value		0		361,000	0		361,000
Options, liability
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value		58,576,000		37,658,000	36,807,000		0
Liability, Transfers In		0		0	0		0
Liability, Transfers Out		0		0	0		0
Liability, Purchases		0		0	0		(35,710,000)
Liability, Sales		0		0	0		0
Realized and unrealized gains (losses), liability		(36,985,000)		(8,873,000)	(15,216,000)		(6,925,000)
Change in Unrealized Gain (Loss), instruments still held, liabilities	[3]	(36,985,000)		(8,873,000)	(15,216,000)		(6,925,000)
Balance Liability Value		21,591,000		28,785,000	21,591,000		28,785,000
Contingent liability payable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value		2,358,000		6,783,000	4,083,000		6,937,000
Liability, Transfers In		0		0	0		0
Liability, Transfers Out		0		0	0		0
Liability, Purchases		(3,100,000)		0	(3,100,000)		0
Liability, Sales		0		(364,000)	(1,725,000)		(518,000)
Realized and unrealized gains (losses), liability		0		0	0		0
Change in Unrealized Gain (Loss), instruments still held, liabilities	[3]	0		0	0		0
Balance Liability Value		$ 5,458,000		$ 6,419,000	$ 5,458,000		$ 6,419,000
[1]	The company completed an initial public offering.
[2]	The company transferred investments to a consolidated fund.
[3]	Unrealized gains/losses are reported in other income (loss) in the accompanying consolidated statements of operations.

Fair Value Measurements for O59

Fair Value Measurements for Operating Entities and Consolidated Funds Fair Value Inputs, Unobservable Inputs, Quantitative Information (Details) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2015		Dec. 31, 2014		Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		$ 63,053		$ 55,006
Financial Liabilities Fair Value Disclosure		282,275		253,288
Assets, Fair Value Disclosure, Recurring		927,523		845,131
Balance Liability Value		27,049		40,890
Contingent liability payable
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Financial Liabilities Fair Value Disclosure		5,458	[1]	4,083	[2]
Balance Liability Value		5,458		4,083		$ 2,358	$ 6,419	$ 6,783	$ 6,937
Common and Preferred Stock
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		3,110		12,269
Convertible Bonds
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		1,129		900		879	1,750	1,750	1,950
Assets, Fair Value Disclosure, Recurring		1,129		900
Warrants and Rights
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value		2,994		1,322		$ 2,316	$ 2,608	$ 3,346	$ 5,805
Assets, Fair Value Disclosure, Recurring		3,871		1,417
Other Investments
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Balance Asset Value	[3]	34,229		3,708
Level 3
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Financial Liabilities Fair Value Disclosure		27,049		40,890
Assets, Fair Value Disclosure, Recurring		$ 63,053		$ 55,006
Level 3 | Options | Market Approach Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility		29.00%
Level 3 | Options | Market Approach Valuation Technique | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility				30.00%
Fair Value Assumptions, Credit Spread				5.00%
Level 3 | Options | Market Approach Valuation Technique | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility				40.00%
Fair Value Assumptions, Credit Spread				7.50%
Level 3 | Contingent liability payable
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Financial Liabilities Fair Value Disclosure		$ 5,458	[1]	$ 4,083	[2]
Level 3 | Contingent liability payable | Income Approach and Market Approach Valuation Techniques
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF discount rate				9.00%
Level 3 | Contingent liability payable | Income Approach and Market Approach Valuation Techniques | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF discount rate		9.00%
Level 3 | Contingent liability payable | Income Approach and Market Approach Valuation Techniques | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF discount rate		24.50%
Level 3 | Contingent liability payable | Market Approach Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Assumptions, Weighted Average Volatility Rate		18.00%
Level 3 | Common and Preferred Stock | Market Approach Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility		42.00%		45.00%
Level 3 | Common and Preferred Stock | Market Approach, Income Approach and Replacement Cost Valuation Techniques [Member] | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Market multiple		1		1
Level 3 | Common and Preferred Stock | Market Approach, Income Approach and Replacement Cost Valuation Techniques [Member] | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Market multiple		5.25		6
Level 3 | Convertible Bonds
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, Fair Value Disclosure, Recurring		$ 1,129		$ 900
Level 3 | Convertible Bonds | Cost Approach Valuation Technique [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Recovery Rate		50.00%		50.00%
Level 3 | Warrants and Rights
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, Fair Value Disclosure, Recurring		$ 2,994		$ 1,322
Level 3 | Warrants and Rights | Market Approach Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Assumptions, Weighted Average Volatility Rate		29.00%		34.00%
Level 3 | Warrants and Rights | Market Approach Valuation Technique | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility		17.00%		20.00%
Level 3 | Warrants and Rights | Market Approach Valuation Technique | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility		60.00%		60.00%
Level 3 | Options | Market Approach Valuation Technique
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility		29.00%
Level 3 | Options | Market Approach Valuation Technique | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility				30.00%
Fair Value Assumptions, Credit Spread				5.00%
Level 3 | Options | Market Approach Valuation Technique | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility				40.00%
Fair Value Assumptions, Credit Spread				7.50%
Options | Derivative Assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, Fair Value Disclosure, Recurring		$ 40,944		$ 49,241
Options | Level 3 | Derivative Assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, Fair Value Disclosure, Recurring		$ 21,591		$ 36,807
[1]	In accordance with the terms of the purchase agreements for acquisitions that closed during 2012 and the third quarter of 2015, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the periods ended August 2016 and December 2020, respectively. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts as of September 30, 2015 can range from zero to $6.7 million.
[2]	In accordance with the terms of a purchase agreement for an acquisitions that closed during 2012, the Company is required to pay to the sellers a portion of future net income of the acquired businesses, if certain revenue targets are achieved through the period ended August 2016. The Company estimated the contingent consideration liability using the income approach (discounted cash flow method) which requires the Company to make estimates and assumptions regarding the future cash flows and profits. Changes in these estimates and assumptions could have a significant impact on the amounts recognized. The undiscounted amounts can range from $0.9 million to $7.1 million.
[3]	The quantitative disclosures exclude financial instruments for which the determination of fair value is based on prices from prior transactions and investments for which NAV per share is used as a practical expedient to determine fair value.

Fair Value Measurements for O60

Fair Value Measurements for Operating Entities and Consolidated Funds Carrying Value Disclosures (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Mar. 10, 2014	Dec. 31, 2013
Cash and cash equivalents		$ 92,854	$ 129,509	$ 66,166		$ 54,720
Cash collateral pledged		9,129	8,306
Securities borrowed		0	676,100
Cash and cash equivalents, Consolidated Funds		16,625	501
Securities loaned		0	682,493
Convertible debt		123,149	118,475
Notes payable and other debt		66,628	67,144
Convertible Debt
Convertible debt, unamortized discount		26,400	31,000		$ 35,700
Level 1
Cash and cash equivalents, Fair Value		92,854	129,509
Securities borrowed, Fair Value		0	660,445
Cash and cash equivalents, Consolidated Funds, Fair Value		16,625	501
Securities Loaned, Fair Value		0	661,533
Level 2
Cash collateral pledged, Fair Value		9,129	8,306
Convertible debt, Fair Value	[1]	158,470	160,713
Notes payable and other debt, Fair Value		$ 69,436	$ 69,548
[1]	The convertible debt include the conversion option and is based on the last broker quote available.

Receivables from and Payable 61

Receivables from and Payable to Brokers (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Brokers and Dealers [Abstract]
Receivable from brokers	$ 115,279	$ 84,679
Payable to brokers	$ 328,902	$ 335,822

Goodwill and Intangibles (Detai

Goodwill and Intangibles (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 0	$ 0	$ 0	$ 0
Concept (Cowen Prime)
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill, Acquired During Period			9,300,000
Finite-lived Intangible Assets Acquired			$ 8,500,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			7 years 8 months 12 days
Amortization of Intangible Assets	$ 0		$ 100,000
Minimum | Concept (Cowen Prime)
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			1 year
Maximum | Concept (Cowen Prime)
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			9 years

Redeemable Non-Controlling In63

Redeemable Non-Controlling Interests in Consolidated Subsidiaries and Funds (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	$ 171,245		$ 171,245		$ 86,076
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,344	$ 4,006	10,980	$ 13,409
Operating Entities
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	15,730		15,730		9,619
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,577	3,223	8,669	9,690
Consolidated Funds
Noncontrolling Interest [Line Items]
Redeemable non-controlling interests in consolidated subsidiaries and funds	155,515		155,515		$ 76,457
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	$ (233)	$ 783	$ 2,311	$ 3,719

Share-Based Compensation and 64

Share-Based Compensation and Employee Ownership Plans Narrative (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Equity Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under compensation plan, in shares	4,200,000			4,200,000
Stock-compensation expense recognized in connection with compensation plan	$ 5.3		$ 3.8	$ 16.2		$ 14.3
Tax benefit of stock-compensation expense recognized in connection with compensation plan	2.1		$ 1.4	$ 2.8		$ 4.4
Equity Plans | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, initial term				7 years
Equity Plans | Employee Stock Option | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period				2 years
Equity Plans | Employee Stock Option | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period				5 years
Equity Plans | Restricted Shares and Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 52.7			$ 52.7
Vested, shares				3,992,005
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	18,363,424	[1]		18,363,424	[1]		17,654,582
Equity Plans | Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period				2 years
Equity Plans | Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period				5 years
Equity Plans | Restricted Stock Units (RSUs) | Non-employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares				157,621
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	497,570			497,570
Equity Plans | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 0.2			$ 0.2			$ 0.2
SAR's, initial term				5 years
Vested, shares				0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	400,000			400,000			400,000
Deferred Cash Award | Cowen Group, Inc. 2010 Equity and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation award, vesting period				4 years
Deferred cash awards, unrecognized compensation expense	$ 32.4			$ 32.4
Deferred Cash Award | Cowen Group, Inc. 2010 Equity and Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred cash award, interest rate				0.70%
Deferred Cash Award | Cowen Group, Inc. 2010 Equity and Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred cash award, interest rate				0.75%
[1]	Performance linked restricted stock units of 1,925,750 were awarded to employees of the Company in December 2013 and January 2014. Of the awards granted, 326,250 have been forfeited through September 30, 2015. The remaining awards, included in the outstanding balance as of September 30, 2015, will vest on June 10, 2019 and will be earned only to the extent that the Company attains specified performance goals relating to its volume-weighted average share price and the aggregate net income for the years from 2014 to 2018. The actual number of RSUs ultimately earned could vary from zero, if performance goals are not met, to as much as 100% of the targeted award. Each RSU is equal to the one share of the Company’s Class A common stock. Compensation expense is recognized to the extent that it is probable that the Company will attain the performance goals.

Share-Based Compensation and 65

Share-Based Compensation and Employee Ownership Plans Deferred Cash (Details) - Cowen Group, Inc. 2010 Equity and Incentive Plan - Deferred Cash Award $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred cash awards granted	$ 12.5
Deferred cash awards, vesting period	4 years
Deferred cash awards, unrecognized compensation expense	$ 32.4
Minimum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred cash award, interest rate	0.70%
Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred cash award, interest rate	0.75%

Share-Based Compensation and 66

Share-Based Compensation and Employee Ownership Plans Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		0.00%
Aggregate Intrinsic Value
Closing stock price, in dollars per share		$ 4.56		$ 4.80
Equity Plans
Shares Subject to Option
Balance outstanding, beginning of period, shares		216,672
Options granted, shares		0
Options exercised, shares		(100,002)
Options expired, shares		(100,003)
Balance outstanding, end of period, shares		16,667
Options exercisable, shares		16,667
Weighted Average Exercise Price/Share
Balance outstanding, beginning of period, in dollars per share		$ 5.65
Options granted, in dollars per share		0
Options exercised, in dollars per share		3.96
Options expired, in dollars per share		7.49
Balance outstanding, end of period, in dollars per share		4.89
Options exercisable, in dollars per share		$ 4.89
Weighted average remaining term, options outstanding		1 year 4 months 6 days	1 year 7 months 6 days
Weighted average remaining term, options exercisable		1 year 4 months 6 days
Aggregate Intrinsic Value
Balance outstanding, beginning of period	[1]	$ 87
Balance outstanding, end of period	[1]	0
Options exercisable	[1]	$ 0
[1]	Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014.

Share-Based Compensation and 67

Share-Based Compensation and Employee Ownership Plans SARs (Details) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Aggregate Intrinsic Value
Closing stock price, in dollars per share		$ 4.56		$ 4.80
Equity Plans
Aggregate Intrinsic Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	[1]	$ 0
Equity Plans | Stock Appreciation Rights
Shares Subject to Option
Balance outstanding, beginning of period, shares		400,000
Granted, shares		0
Acquired, shares		0
Expired, shares		0
Balance outstanding, end of period, shares		400,000
Balance exercisable, shares		0
Weighted Average Exercise Price/Share
Balance outstanding, beginning of period, in dollars per share		$ 2.90
Granted, in dollars per share		0
Acquired, in dollars per share		0
Expired, in dollars per share		0
Balance outstanding, end of period, in dollars per share		$ 2.90
Weighted Average Remaining Term Outstanding		2 years 5 months 16 days	3 years 2 months 16 days
Aggregate Intrinsic Value
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	[2]	$ 781		$ 913
Unrecognized compensation expense		$ 200		$ 200
[1]	Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014.
[2]	Based on the Company's closing stock price of $4.56 on September 30, 2015 and $4.80 on December 31, 2014.

Share-Based Compensation and 68

Share-Based Compensation and Employee Ownership Plans Restricted Shares and Restricted Stock Units (Details) - Equity Plans - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Weighted-Average Grant Date Fair Value
Allocated Share-based Compensation Expense		$ 5.3	$ 3.8	$ 16.2	$ 14.3
Restricted Shares and Restricted Stock Units (RSUs)
Nonvested Restricted Shares and Restricted Stock Units
Balance outstanding, beginning of period, shares				17,654,582
Granted, shares				5,718,605
Vested, shares				(3,992,005)
Cancelled, shares				0
Forfeited, shares				(1,017,758)
Balance outstanding, end of period, shares	[1]	18,363,424		18,363,424
Weighted-Average Grant Date Fair Value
Balance outstanding, beginning of period, in dollars per share				$ 3.70
Granted, in dollars per share				4.79
Vested, in dollars per share				3.08
Cancelled, in dollars per share				0
Forfeited, in dollars per share				3.41
Balance outstanding, end of period, in dollars per share	[1]	$ 4.19		$ 4.19
Unrecognized compensation expense		$ 52.7		$ 52.7
Weighted-average recognition period for unrecognized compensation expense				1 year 7 months 27 days
Performance based restricted stock
Nonvested Restricted Shares and Restricted Stock Units
Granted, shares				1,925,750
Forfeited, shares				(326,250)
[1]	Performance linked restricted stock units of 1,925,750 were awarded to employees of the Company in December 2013 and January 2014. Of the awards granted, 326,250 have been forfeited through September 30, 2015. The remaining awards, included in the outstanding balance as of September 30, 2015, will vest on June 10, 2019 and will be earned only to the extent that the Company attains specified performance goals relating to its volume-weighted average share price and the aggregate net income for the years from 2014 to 2018. The actual number of RSUs ultimately earned could vary from zero, if performance goals are not met, to as much as 100% of the targeted award. Each RSU is equal to the one share of the Company’s Class A common stock. Compensation expense is recognized to the extent that it is probable that the Company will attain the performance goals.

Defined Benefit Plan - Quarte69

Defined Benefit Plan - Quarterly (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 0	$ 0
Interest cost	18,000	85,000
Expected return on plan assets	(168,000)	(300,000)
Amortization of loss / (gain)	(7,000)	(7,000)
Amortization of prior service cost	0	0
Effect of settlement	0	0
Net periodic benefit cost	$ (157,000)	$ (222,000)

Income Taxes - Quarterly (Detai

Income Taxes - Quarterly (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective Income Tax Rate, Percent	17.81%	0.69%
Statutory rate, Percent	35.00%	35.00%
Undistributed Earnings of Foreign Subsidiaries	$ 0.8		$ 1.1
Tax Liabilities, Undistributed Foreign Earnings	$ 0.1		$ 0.2

Commitments and Contingencies71

Commitments and Contingencies (Details)		3 Months Ended		9 Months Ended
		Sep. 30, 2015USD ($)cowenfund	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)cowenfund	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)	Apr. 30, 2013USD ($)
Lease Obligations
Net rent expense		$ 4,600,000	$ 4,300,000	$ 13,300,000	$ 12,500,000
Future minimum annual lease and service payments
Sublease income related to operating leases		500,000	$ 500,000	1,400,000	$ 1,300,000
Affiliated Entity
Future minimum annual lease and service payments
Other commitments, unfunded amount				9,600,000
Affiliated Entity | Healthcare Royalty Partners
Future minimum annual lease and service payments
Contractual obligation		45,400,000		45,400,000
Funding toward commitments				$ 36,000,000
Affiliated Entity | Healthcare Royalty Partners | Minimum
Future minimum annual lease and service payments
Expected call period				2 years
Affiliated Entity | Healthcare Royalty Partners | Maximum
Future minimum annual lease and service payments
Expected call period				5 years
Affiliated Entity | Starboard Leaders Fund LP
Future minimum annual lease and service payments
Funding toward commitments				$ 900,000
Affiliated Entity | Formation 8 Partners Fund I LP
Future minimum annual lease and service payments
Other commitments, unfunded amount				1,400,000
Affiliated Entity | Formation 8 Partners Hardware Fund I, L.P.
Future minimum annual lease and service payments
Other commitments, unfunded amount				1,100,000
Clawback Obligation
Future minimum annual lease and service payments
Contractual obligation		$ 6,200,000		$ 6,200,000		$ 6,200,000
Commitment to Invest | Affiliated Entity | Starboard Leaders Fund LP
Future minimum annual lease and service payments
Contractual obligation							$ 1,000,000
Commitment to Invest | Affiliated Entity | Formation 8 Partners Fund I LP
Future minimum annual lease and service payments
Term of capital commitment				1 year
Commitment to Invest | Affiliated Entity | Formation 8 Partners Hardware Fund I, L.P.
Future minimum annual lease and service payments
Term of capital commitment				1 year
Unfunded Commitments
Future minimum annual lease and service payments
Number of real estate investments, in investments | cowenfund		4		4
RCG Longview Partners II, LLC | Clawback Obligation
Future minimum annual lease and service payments
Contractual obligation		$ 6,200,000		$ 6,200,000		$ 6,200,000
Equipment Leases
Future minimum annual lease and service payments
Contractual Obligation, Due in remainder of current year	[1]	700,000		700,000
Contractual Obligation, Due in Second Year	[1]	2,502,000		2,502,000
Contractual Obligation, Due in Third Year	[1]	2,301,000		2,301,000
Contractual Obligation, Due in Fourth Year	[1]	2,221,000		2,221,000
Contractual Obligation, Due in Fifth Year	[1]	813,000		813,000
Thereafter	[1]	0		0
Future minimum annual lease and service payments	[1]	8,537,000		8,537,000
Service Payments
Future minimum annual lease and service payments
Contractual Obligation, Due in remainder of current year		4,490,000		4,490,000
Contractual Obligation, Due in Second Year		12,391,000		12,391,000
Contractual Obligation, Due in Third Year		6,245,000		6,245,000
Contractual Obligation, Due in Fourth Year		4,162,000		4,162,000
Contractual Obligation, Due in Fifth Year		1,375,000		1,375,000
Thereafter		0		0
Future minimum annual lease and service payments		28,663,000		28,663,000
Facility Leases
Future minimum annual lease and service payments
Contractual Obligation, Due in remainder of current year	[2]	5,094,000		5,094,000
Contractual Obligation, Due in Second Year	[2]	19,401,000		19,401,000
Contractual Obligation, Due in Third Year	[2]	16,030,000		16,030,000
Contractual Obligation, Due in Fourth Year	[2]	15,621,000		15,621,000
Contractual Obligation, Due in Fifth Year	[2]	14,822,000		14,822,000
Thereafter	[2]	47,064,000		47,064,000
Future minimum annual lease and service payments	[2]	$ 118,032,000		$ 118,032,000
[1]	Equipment Leases include the Company's commitments relating to operating and capital leases. See Note 14 for further information on the capital lease minimum payments which are included in the table.
[2]	The Company has entered into various agreements to sublease certain of its premises. The Company recorded sublease income related to these leases of $0.5 million and $0.5 million for the three months ended September 30, 2015 and 2014 and $1.4 million and $1.3 million for the nine months ended September 30, 2015 and 2014, respectively.

Convertible Debt and Notes Pa72

Convertible Debt and Notes Payable (Details)		Oct. 10, 2014USD ($)	Sep. 30, 2015USD ($)letters_of_credit	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)letters_of_credit	Sep. 30, 2014USD ($)	Jan. 31, 2014USD ($)	Jan. 30, 2015USD ($)	Dec. 31, 2014USD ($)	Mar. 10, 2014USD ($)$ / shares
Debt and Capital Lease Obligations [Line Items]
Interest Expense, Lessee, Assets under Capital Lease			$ 100,000	$ 100,000	$ 100,000	$ 200,000
Components of short-term borrowings and other debt
Convertible debt			123,149,000		123,149,000				$ 118,475,000
Notes Payable			63,250,000		63,250,000				63,250,000
Other Note payable			355,000		355,000				0
Capital lease obligations			3,023,000		3,023,000				3,894,000
Debt, Long-term and Short-term, Combined Amount			189,777,000		189,777,000				185,619,000
Amortization of debt discount					4,674,000	3,241,000
Cash convertible note hedge transaction					0	149,500,000
Capital Lease Obligations Incurred							$ 7,600,000
Capital Leases, Income Statement, Interest Expense			100,000	100,000	100,000	200,000
Future minimum lease payments for capital lease obligations
2,015			330,000		330,000
2,016			1,025,000		1,025,000
2,017			938,000		938,000
2,018			938,000		938,000
2,019			78,000		78,000
Thereafter			0		0
Subtotal			3,309,000		3,309,000
Less: Amount representing interest	[1]		(286,000)		(286,000)
Capital lease obligations			$ 3,023,000		$ 3,023,000				3,894,000
Number of Letters of Credit | letters_of_credit			7		7
Revolving Credit Facility
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			$ 25,000,000		$ 25,000,000
Line of Credit Facility, Commitment Fee Percentage					3.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage					0.38%
Minimum
Components of short-term borrowings and other debt
Capital Lease Obligation, Initial Term					48 months
Capital leases, interest rate			0.60%		0.60%
Maximum
Components of short-term borrowings and other debt
Capital Lease Obligation, Initial Term					60 months
Capital leases, interest rate			6.03%		6.03%
Cash Convertible Note Economic Hedge And Warrant Transaction
Components of short-term borrowings and other debt
Cash convertible note hedge transaction						20,500,000
Treasury Stock
Components of short-term borrowings and other debt
Cash convertible note hedge transaction						300,000
Letter of Credit, San Francisco Office, Expires October 2025 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			$ 710,000		$ 710,000
Letter of Credit, NY Office, Expires February 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			1,000,000		1,000,000
Letter of Credit, Boston Office, Expires March 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			382,000		382,000
Letter of Credit, NY Office 1, Expires May 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			355,000		355,000
Letter of Credit, NY Office 2, Expires May 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			1,861,000		1,861,000
Letter of Credit, NY Office 3, Expires October 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			794,000		794,000
Letter of Credit, NY Office 4, Expires October 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			3,935,000		3,935,000
Convertible Debt
Components of short-term borrowings and other debt
Debt Instrument, Face Amount										$ 149,500,000
Interest rate										3.00%
Principal amount of notes being converted										$ 1,000
Interest on Convertible Debt, Net of Tax			1,100,000	1,100,000	3,400,000	1,100,000
Debt Instrument, Convertible, Conversion Price | $ / shares										$ 5.33
Convertible debt, unamortized discount			26,400,000		26,400,000				$ 31,000,000	$ 35,700,000
Amortization of debt discount			1,600,000	$ 1,500,000	4,700,000	$ 3,200,000
Debt Instrument, Interest Rate, Effective Percentage										8.89%
Debt Issuance Cost					3,700,000
Repayments on long-term and short-term borrowings
2,015			0		0
2,016			4,485,000		4,485,000
2,017			4,485,000		4,485,000
2,018			4,485,000		4,485,000
2,019			151,743,000		151,743,000
Thereafter			0		0
Subtotal			165,198,000		165,198,000
Less: Amount representing interest	[1]		(42,049,000)		(42,049,000)
Senior Notes
Components of short-term borrowings and other debt
Notes Payable			63,250,000		63,250,000
Debt Instrument, Face Amount		$ 63,300,000
Interest rate		8.25%
Interest on Convertible Debt, Net of Tax			1,300,000		3,900,000
Debt Issuance Cost		$ 2,900,000
Repayments on long-term and short-term borrowings
2,015			1,304,000		1,304,000
2,016			5,218,000		5,218,000
2,017			5,218,000		5,218,000
2,018			5,218,000		5,218,000
2,019			5,218,000		5,218,000
Thereafter			73,686,000		73,686,000
Subtotal			95,862,000		95,862,000
Less: Amount representing interest	[1]		(32,612,000)		(32,612,000)
Insurance Note
Components of short-term borrowings and other debt
Other Note payable			355,000		355,000			$ 2,000,000
Interest rate								1.33%
Monthly payment					200,000
Repayments on long-term and short-term borrowings
2,015			361,000		361,000
2,016			0		0
2,017			0		0
2,018			0		0
2,019			0		0
Thereafter			0		0
Subtotal			361,000		361,000
Less: Amount representing interest	[1]		$ (6,000)		$ (6,000)
Common Stock Class A
Components of short-term borrowings and other debt
Class of Warrant, Exercise Price of Warrants or Rights | $ / shares										$ 7.18
[1]	Amount necessary to reduce net minimum payments to present value calculated at the Company's implicit rate at inception. This amount also includes the unamortized discount on the convertible debt.

Stockholder's Equity Stockholde

Stockholder's Equity Stockholder's Equity - Quarterly (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	May. 19, 2015
Equity, Class of Stock [Line Items]
Proceeds from Issuance of Preferred Stock, net of issuance costs		$ 117,194	$ 0
Convertible Preferred Stock, Shares Issued upon Conversion				152.2476
Convertible Preferred Stock, Threshold Percentage of Stock Price Trigger		150.00%
Treasury Stock, Shares [Roll Forward]
Treasury stock, shares, beginning of period		23,507,656
Treasury stock reissued, shares		0
Purchase of treasury stock, shares		7,694,214
Treasury stock, shares, end of period	32,776,819	32,776,819
Treasury stock, cost, beginning of period		$ 79,771
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions		8,556	$ 5,610
Treasury stock reissued, cost		0
Purchase of treasury stock, cost		41,697
Treasury stock, cost, end of period	$ 130,024	$ 130,024
Treasury stock, average cost per share, beginning of period, in dollars per share		$ 3.39
Treasury stock reissued, average cost per share, in dollars per share		0
Purchase of treasury stock, average cost per share, in dollars per share		5.42
Treasury stock, average cost per share, end of period, in dollars per share	$ 3.97	$ 3.97
Treasury Stock
Treasury Stock, Shares [Roll Forward]
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions		1,574,949
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions		$ 8,556
Shares purchased for minimum tax withholding under the Equity Plan or other similar transactions, Average Cost Per Share		$ 5.43
Call Option
Equity, Class of Stock [Line Items]
Option indexed to Issuer's Equity, Value				$ 15,900
Minimum
Equity, Class of Stock [Line Items]
Convertible Preferred Stock, Threshold Consecutive Trading Days		20 days
Minimum | Call Option
Equity, Class of Stock [Line Items]
Option Indexed to Issuer's Equity, Strike Price		$ 6.57
Maximum
Equity, Class of Stock [Line Items]
Convertible Preferred Stock, Threshold Consecutive Trading Days		30 days
Maximum | Call Option
Equity, Class of Stock [Line Items]
Option Indexed to Issuer's Equity, Strike Price		$ 8.39
Cumulative Preferred Stock
Equity, Class of Stock [Line Items]
Preferred stock issuance, net of issuance costs		120,750
Convertible Preferred Stock
Equity, Class of Stock [Line Items]
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs		$ 3,400
Preferred Stock, Dividend Rate, Percentage		5.625%
Dividends	$ 1,600	$ 2,400
Preferred Stock, Liquidation Preference Per Share				$ 1,000

Accumulated Other Comprehensi74

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income / (Loss) [Abstract]
Foreign Currency Translations	[1]	$ 13	$ 15	$ 17	$ 248
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	[1]	(4)	(233)
Defined Benefit Plans	[1]	0	257	0	344
Total defined benefit pension plan	[1]	0	87
Accumulated other comprehensive income (loss)		13	272	$ 17	$ 592
Other Comprehensive Income (Loss), Net of Tax		$ (4)	$ (320)
[1]	During the periods presented, the Company did not have material reclassifications out of other comprehensive income.

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Computation of earnings per share:
Net income (loss)	$ (6,002)	$ 10,529	$ 24,048	$ 38,154
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	4,344	4,006	10,980	13,409
Net income (loss) attributable to Cowen Group, Inc.	(10,346)	6,523	13,068	24,745
Preferred Stock Dividends	1,603	0	2,358	0
Net income (loss) attributable to Cowen Group, Inc. common stockholders	$ (11,949)	$ 6,523	$ 10,710	$ 24,745
Shares for basic and diluted calculations:
Weighted average shares used in basic computation, shares	109,191,000	114,969,000	111,050,000	115,407,000
Weighted average shares used in diluted computation, shares	109,191,000	118,801,000	117,249,000	120,027,000
Earnings (loss) per share:
Earnings Per Share, Basic (in dollars per share)	$ (0.11)	$ 0.06	$ 0.10	$ 0.21
Earnings Per Share, Diluted (in dollars per share)	$ (0.11)	$ 0.05	$ 0.09	$ 0.21
Stock Options
Shares for basic and diluted calculations:
Shares attributable to share-based payment awards, shares	0	0	19,000	0
Performance based restricted stock
Shares for basic and diluted calculations:
Shares attributable to share-based payment awards, shares	0	0	266,000	0
Stock Appreciation Rights
Shares for basic and diluted calculations:
Shares attributable to share-based payment awards, shares	0	59,000	152,000	57,000
Restricted Stock
Shares for basic and diluted calculations:
Shares attributable to share-based payment awards, shares	0	3,773,000	5,762,000	4,563,000
Common Stock Class A
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Common stock, shares outstanding, shares	107,098,068	113,634,803	107,098,068	113,634,803	111,691,199	115,026,633
Common stock, restricted shares, shares	497,570		497,570		424,479

Segment Reporting (Details)

Segment Reporting (Details)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)segmentcustomer	Sep. 30, 2014USD ($)customer	Dec. 31, 2013customer
Segment Reporting Information [Line Items]
Number of Operating Segments | segment				2
Revenues
Investment banking		$ 53,012,000	$ 45,799,000	$ 186,763,000	$ 125,653,000
Brokerage		41,085,000	34,334,000	111,496,000	100,475,000
Management fees		10,519,000	9,796,000	31,169,000	28,412,000
Incentive income		93,000	(837,000)	365,000	4,385,000
Investment Income		0	0	0	0
Interest and dividends		3,604,000	13,725,000	9,846,000	35,437,000
Reimbursement from affiliates		3,355,000	2,473,000	10,499,000	7,391,000
Other revenue		1,312,000	1,120,000	2,684,000	2,427,000
Total revenues		113,254,000	107,101,000	353,956,000	306,680,000
Expenses
Non-interest expense		92,966,000	99,636,000	335,902,000	295,603,000
Interest and dividends		7,367,000	12,429,000	19,241,000	29,694,000
Total expenses		100,967,000	112,700,000	356,769,000	326,632,000
Other income (loss)
Total other income (loss)		(23,370,000)	16,269,000	32,073,000	58,372,000
Income tax expense (benefit)		(5,081,000)	141,000	5,212,000	266,000
(Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds		(4,344,000)	(4,006,000)	(10,980,000)	(13,409,000)
Economic Income (Loss) / Net income (loss) attributable to Cowen Group, Inc.		(10,346,000)	6,523,000	$ 13,068,000	$ 24,745,000
Number of major customers | customer				0	0	0
Reported Under Economic Income / (Loss)
Revenues
Investment banking		53,012,000	45,799,000	$ 186,763,000	$ 125,653,000
Brokerage		41,875,000	35,583,000	112,333,000	104,983,000
Management fees		18,021,000	16,319,000	51,167,000	46,574,000
Incentive income		(8,629,000)	4,488,000	(1,081,000)	16,900,000
Investment Income		(22,024,000)	7,463,000	19,072,000	37,232,000
Interest and dividends		0	0	0	0
Reimbursement from affiliates		0	0	0	0
Other revenue		564,000	396,000	689,000	494,000
Total revenues		82,819,000	110,048,000	368,943,000	331,836,000
Expenses
Non-interest expense		90,854,000	98,804,000	331,103,000	292,334,000
Interest and dividends		4,257,000	2,664,000	12,425,000	5,961,000
Total expenses		95,111,000	101,468,000	343,528,000	298,295,000
Other income (loss)
Total other income (loss)		0	0	0	0
Income tax expense (benefit)		0	0	0	0
(Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds		(2,231,000)	(1,877,000)	(6,128,000)	(8,320,000)
Economic Income (Loss) / Net income (loss) attributable to Cowen Group, Inc.		(14,523,000)	6,703,000	19,287,000	25,221,000
Alternative Investment | Reported Under Economic Income / (Loss)
Revenues
Investment banking		0	0	0	0
Brokerage		18,000	15,000	41,000	40,000
Management fees		17,739,000	16,319,000	50,885,000	46,574,000
Incentive income		(8,629,000)	4,488,000	(1,081,000)	16,900,000
Investment Income		(16,781,000)	4,064,000	14,309,000	29,025,000
Interest and dividends		0	0	0	0
Reimbursement from affiliates		0	0	0	0
Other revenue		(9,000)	43,000	84,000	140,000
Total revenues		(7,662,000)	24,929,000	64,238,000	92,679,000
Expenses
Non-interest expense		6,133,000	21,754,000	57,164,000	71,421,000
Interest and dividends		2,970,000	1,852,000	8,880,000	5,083,000
Total expenses		9,103,000	23,606,000	66,044,000	76,504,000
Other income (loss)
Total other income (loss)		0	0	0	0
Income tax expense (benefit)		0	0	0	0
(Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds		(2,231,000)	(1,877,000)	(6,128,000)	(8,320,000)
Economic Income (Loss) / Net income (loss) attributable to Cowen Group, Inc.		(18,996,000)	(554,000)	(7,934,000)	7,855,000
Broker-Dealer | Reported Under Economic Income / (Loss)
Revenues
Investment banking		53,012,000	45,799,000	186,763,000	125,653,000
Brokerage		41,857,000	35,568,000	112,292,000	104,943,000
Management fees		282,000	0	282,000	0
Incentive income		0	0	0	0
Investment Income		(5,243,000)	3,399,000	4,763,000	8,207,000
Interest and dividends		0	0	0	0
Reimbursement from affiliates		0	0	0	0
Other revenue		573,000	353,000	605,000	354,000
Total revenues		90,481,000	85,119,000	304,705,000	239,157,000
Expenses
Non-interest expense		84,721,000	77,050,000	273,939,000	220,913,000
Interest and dividends		1,287,000	812,000	3,545,000	878,000
Total expenses		86,008,000	77,862,000	277,484,000	221,791,000
Other income (loss)
Total other income (loss)		0	0	0	0
Income tax expense (benefit)		0	0	0	0
(Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds		0	0	0	0
Economic Income (Loss) / Net income (loss) attributable to Cowen Group, Inc.		4,473,000	7,257,000	27,221,000	17,366,000
Funds Consolidation | Reconciliation from Economic Income / (Loss) to U.S. GAAP
Revenues
Investment banking		0	0	0	0
Brokerage		0	0	0	0
Management fees		(371,000)	(246,000)	(937,000)	(723,000)
Incentive income		29,000	(34,000)	(278,000)	(188,000)
Investment Income		0	0	0	0
Interest and dividends		0	0	0	0
Reimbursement from affiliates		(85,000)	119,000	(261,000)	(45,000)
Other revenue		0	0	0	0
Total revenues		(153,000)	530,000	(342,000)	1,544,000
Expenses
Non-interest expense		0	0	0	0
Interest and dividends		0	0	0	0
Total expenses		634,000	635,000	1,626,000	1,335,000
Other income (loss)
Total other income (loss)		554,000	888,000	4,278,000	3,509,000
Income tax expense (benefit)		0	0	0	0
(Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds		233,000	(783,000)	(2,310,000)	(3,718,000)
Economic Income (Loss) / Net income (loss) attributable to Cowen Group, Inc.		0	0	0	0
Significant Reconciling Items | Reconciliation from Economic Income / (Loss) to U.S. GAAP
Revenues
Investment banking		0	0	0	0
Brokerage	[1]	(790,000)	(1,249,000)	(837,000)	(4,508,000)
Management fees	[2]	(7,131,000)	(6,277,000)	(19,061,000)	(17,439,000)
Incentive income	[2]	8,693,000	(5,291,000)	1,724,000	(12,327,000)
Investment Income	[3]	22,024,000	(7,463,000)	(19,072,000)	(37,232,000)
Interest and dividends	[1],[3]	3,604,000	13,725,000	9,846,000	35,437,000
Reimbursement from affiliates	[4]	3,440,000	2,354,000	10,760,000	7,436,000
Other revenue	[3]	748,000	724,000	1,995,000	1,933,000
Total revenues		30,588,000	(3,477,000)	(14,645,000)	(26,700,000)
Expenses
Non-interest expense	[3],[5]	2,112,000	832,000	4,799,000	3,269,000
Interest and dividends	[1],[3]	3,110,000	9,765,000	6,816,000	23,733,000
Total expenses		5,222,000	10,597,000	11,615,000	27,002,000
Other income (loss)
Total other income (loss)	[3]	(23,924,000)	15,381,000	27,795,000	54,863,000
Income tax expense (benefit)	[6]	(5,081,000)	141,000	5,212,000	266,000
(Income) loss attributable to redeemable non-controlling interests in consolidated subsidiaries and funds		(2,346,000)	(1,346,000)	(2,542,000)	(1,371,000)
Economic Income (Loss) / Net income (loss) attributable to Cowen Group, Inc.		4,177,000	(180,000)	(6,219,000)	(476,000)
Consolidated Funds
Revenues
Total revenues		274,000	691,000	1,134,000	2,500,000
Expenses
Total expenses		634,000	635,000	1,626,000	1,335,000
Consolidated Funds | Reported Under Economic Income / (Loss)
Revenues
Total revenues		0	0	0	0
Expenses
Total expenses		0	0	0	0
Consolidated Funds | Alternative Investment | Reported Under Economic Income / (Loss)
Revenues
Total revenues		0	0	0	0
Expenses
Total expenses		0	0	0	0
Consolidated Funds | Broker-Dealer | Reported Under Economic Income / (Loss)
Revenues
Total revenues		0	0	0	0
Expenses
Total expenses		0	0	0	0
Consolidated Funds | Funds Consolidation | Reconciliation from Economic Income / (Loss) to U.S. GAAP
Revenues
Total revenues		274,000	691,000	1,134,000	2,500,000
Expenses
Total expenses		634,000	635,000	1,626,000	1,335,000
Consolidated Funds | Significant Reconciling Items | Reconciliation from Economic Income / (Loss) to U.S. GAAP
Revenues
Total revenues		0	0	0	0
Expenses
Total expenses		$ 0	$ 0	$ 0	$ 0
[1]	Economic Income (Loss) recognizes stock borrow/loan activity (prior to January 2015) and other brokerage dividends as brokerage revenue.
[2]	Economic Income (Loss) recognizes revenues (i) net of distribution fees paid to agents and (ii) our proportionate share of management and incentive fees of certain real estate operating entities and the activist business.
[3]	Economic Income (Loss) recognizes Company income from proprietary trading (including interest and dividends) net of related expenses.
[4]	Reimbursement from affiliates is shown as a reduction of Economic Income expenses, but is included as a part of revenues under US GAAP.
[5]	Economic Income (Loss) recognizes the Company's proportionate share of expenses for certain real estate and other operating entities for which the investments are recorded under the equity method of accounting for investments.
[6]	Economic Income (Loss) excludes income taxes as management does not consider this item when evaluating the performance of the segment.

Regulatory Requirements (Detail

Regulatory Requirements (Details)	Sep. 30, 2015USD ($)
Cowen and Company
Regulatory Requirements for Broker-Dealers [Line Items]
Net capital requirement under alternative method	$ 1,000,000
Net capital	123,400,000
Excess capital	122,400,000
ATM Execution
Regulatory Requirements for Broker-Dealers [Line Items]
Minimum net capital required	250,000
Net capital	4,700,000
Excess capital	4,400,000
Concept (Cowen Prime)
Regulatory Requirements for Broker-Dealers [Line Items]
Minimum net capital required	250,000
Net capital	4,200,000
Excess capital	3,900,000
U.K. Financial Services Authority | Raimus U.K., Ltd.
Regulatory Requirements for Broker-Dealers [Line Items]
Financial resources	290,000
Financial resources requirement	60,000
Excess financial resources	230,000
U.K. Financial Services Authority | Cowen International Limited
Regulatory Requirements for Broker-Dealers [Line Items]
Financial resources	3,300,000
Financial resources requirement	2,000,000
Excess financial resources	1,300,000
H.K. Securities and Futures Commission | Cowen and Company (Asia) Limited
Regulatory Requirements for Broker-Dealers [Line Items]
Financial resources	500,000
Financial resources requirement	400,000
Excess financial resources	$ 100,000

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Fees receivable, net of allowance	$ 54,107		$ 54,107		$ 46,498
Redeemable non-controlling interests, Related Party	(171,245)		(171,245)		(86,076)
Net income (loss) attributable to redeemable non-controlling interests, Related Party	(4,344)	$ (4,006)	(10,980)	$ (13,409)
June 29, 2015 | Real Estate Equity Investment
Related Party Transaction [Line Items]
Interest Income, Related Party	300		300
Real estate loan	15,000		$ 15,000
Effective interest rate			8.82%
July 29, 2015 | Real Estate Equity Investment
Related Party Transaction [Line Items]
Real estate loan	900		$ 900
Effective interest rate			6.00%
Employees
Related Party Transaction [Line Items]
Redeemable non-controlling interests, Related Party	25,000		$ 25,000		15,000
Net income (loss) attributable to redeemable non-controlling interests, Related Party	(5,500)	(3,200)	$ (10,300)	(10,100)
Minimum | Employee Loans
Related Party Transaction [Line Items]
Forgivable Loans, Vesting Period			1 year
Maximum | Employee Loans
Related Party Transaction [Line Items]
Forgivable Loans, Vesting Period			3 years
Affiliated Entity
Related Party Transaction [Line Items]
Fees receivable, net of allowance	5,400		$ 5,400		5,100
Affiliated Entity | Fees Payable
Related Party Transaction [Line Items]
Fees payable to related parties	100		100		100
Affiliated Entity | Management Fee and Incentive Income
Related Party Transaction [Line Items]
Reimbursement to affiliated funds				800
Employees
Related Party Transaction [Line Items]
Due from employees	3,800		3,800		6,100
Forgivable Loan Balances	1,700		1,700		3,900
Amortization on Forgivable Loans	600	$ 1,300	2,600	$ 3,200
Investor
Related Party Transaction [Line Items]
Due to Affiliate	$ 300		$ 300		$ 500

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events (Details) - Subsequent Event $ in Millions	Oct. 28, 2015USD ($)
Subsequent Event [Line Items]
Stock Repurchase Program, Authorized Amount	$ 19.1
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 25