Virtu Financial (VIRT) 10-Q 8 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 08, 2018
Entity Information [Line Items]
Entity Registrant Name	Virtu Financial, Inc.
Entity Central Index Key	1,592,386
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Small Business	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		106,145,686
Class C
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		14,001,131
Class D
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		69,091,740

Condensed Consolidated Statemen

Condensed Consolidated Statements of Financial Condition (unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 415,933	$ 532,887
Securities borrowed	1,305,789	1,471,172
Securities purchased under agreements to resell	10,014	0
Receivables from broker dealers and clearing organizations	1,115,764	972,018
Trading assets, at fair value:
Financial instruments owned	2,374,124	2,117,579
Financial instruments owned and pledged	552,629	595,043
Property, equipment and capitalized software (net of accumulated depreciation of $324,732 and $375,656 as of September 30, 2018 and December 31, 2017, respectively)	117,501	137,018
Goodwill	836,583	844,883
Intangibles (net of accumulated amortization of $142,564 and $123,408 as of September 30, 2018 and December 31, 2017, respectively)	90,069	111,224
Deferred tax assets	178,087	125,760
Assets of business held for sale	0	55,070
Other assets ($42,375 and $98,364, at fair value, as of September 30, 2018 and December 31, 2017, respectively)	242,037	357,352
Total assets	7,238,530	7,320,006
Liabilities
Short-term borrowings	14,567	27,883
Securities loaned	800,145	754,687
Securities sold under agreements to repurchase	301,238	390,642
Payables to broker dealers and clearing organizations	952,343	716,205
Trading liabilities, at fair value:
Financial instruments sold, not yet purchased	2,398,094	2,384,598
Tax receivable agreement obligations	199,264	147,040
Accounts payable and accrued expenses and other liabilities	284,241	358,825
Long-term borrowings	904,027	1,388,548
Total liabilities	5,853,919	6,168,428
Commitments and Contingencies (Note 15)
Virtu Financial Inc. Stockholders' equity
Treasury stock, at cost, 2,178,771 and 616,923 shares at September 30, 2018 and December 31, 2017, respectively	(55,005)	(11,041)
Additional paid-in capital	1,002,059	900,746
Retained earnings (accumulated deficit)	49,647	(62,129)
Accumulated other comprehensive income	721	2,991
Total Virtu Financial Inc. stockholders' equity	997,424	830,569
Noncontrolling interest	387,187	321,009
Total equity	1,384,611	1,151,578
Total liabilities and equity	7,238,530	7,320,006
Class A
Virtu Financial Inc. Stockholders' equity
Common stock (par value $0.00001)	1	1
Class B
Virtu Financial Inc. Stockholders' equity
Common stock (par value $0.00001)	0	0
Class C
Virtu Financial Inc. Stockholders' equity
Common stock (par value $0.00001)	0	0
Class D
Virtu Financial Inc. Stockholders' equity
Common stock (par value $0.00001)	$ 1	$ 1

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Financial Condition (unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accumulated depreciation	$ 324,732	$ 375,656
Intangibles accumulated amortization	142,564	123,408
Fair value of other assets	$ 42,375	$ 98,364
Treasury stock, shares	2,178,771	616,923
Class A
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	108,507,227	90,415,532
Common stock, shares outstanding	106,328,456	89,798,609
Class B
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	175,000,000	175,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0
Class C
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	14,001,131	17,880,239
Common stock, shares outstanding	14,001,131	17,880,239
Class D
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	175,000,000	175,000,000
Common stock, shares issued	69,091,740	79,610,490
Common stock, shares outstanding	69,091,740	79,610,490

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Trading income, net	$ 235,699	$ 203,907	$ 900,454	$ 479,644
Interest and dividends income	21,451	20,430	61,337	30,933
Commissions, net and technology services	40,252	43,351	140,661	49,237
Total revenue	295,123	271,286	1,438,303	563,461
Operating Expenses:
Brokerage, exchange and clearance fees, net	68,638	64,584	229,779	170,253
Communication and data processing	39,516	45,998	137,793	83,190
Employee compensation and payroll taxes	44,827	72,341	150,723	111,053
Payments for order flow	18,283	12,071	50,381	12,071
Interest and dividends expense	32,566	31,242	101,199	58,456
Operations and administrative	17,254	24,183	53,671	35,931
Depreciation and amortization	16,012	15,602	47,558	29,157
Amortization of purchased intangibles and acquired capitalized software	6,367	6,440	20,042	6,546
Termination of office leases	1,440	0	23,300	0
Debt issue cost related to debt refinancing and prepayment	3,347	4,869	11,727	9,351
Transaction advisory fees and expenses	(261)	15,677	8,985	24,188
Charges related to share based compensation at IPO	0	181	24	545
Financing interest expense on long-term borrowings	17,709	24,593	55,536	40,141
Total operating expenses	265,698	317,781	890,718	580,882
Income (loss) before income taxes and noncontrolling interest	29,425	(46,495)	547,585	(17,421)
Provision for (benefit from) income taxes	13,815	(6,505)	75,330	(2,918)
Net income (loss)	15,610	(39,990)	472,255	(14,503)
Noncontrolling interest	(6,998)	26,472	(263,682)	6,466
Net income (loss) available for common stockholders	$ 8,612	$ (13,518)	$ 208,573	$ (8,037)
Earnings per share
Basic (in dollars per share)	$ 0.08	$ (0.17)	$ 2.07	$ (0.17)
Diluted (in dollars per share)	$ 0.08	$ (0.17)	$ 2.04	$ (0.17)
Weighted average common shares outstanding
Basic (in shares)	106,692,034	79,199,142	99,038,084	53,520,346
Diluted (in shares)	107,128,206	79,199,142	100,468,860	53,520,346
Comprehensive income
Net income (loss)	$ 15,610	$ (39,990)	$ 472,255	$ (14,503)
Other comprehensive income
Foreign exchange translation adjustment, net of taxes	(666)	2,558	(3,713)	8,300
Comprehensive income (loss)	14,944	(37,432)	468,542	(6,203)
Less: Comprehensive income attributable to noncontrolling interest	(6,708)	25,122	(262,239)	1,014
Comprehensive income (loss) attributable to common stockholders	8,236	(12,310)	206,303	(5,189)
Other, net
Revenues:
Total revenue	$ (2,279)	$ 3,598	$ 335,851	$ 3,647

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Equity (unaudited) - USD ($) $ in Thousands	Total	Class A	Total Virtu Financial Inc. Stockholders' Equity	Common StockClass A	Common StockClass C	Common StockClass D	Treasury Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Non-Controlling Interest
Balance at beginning period (in shares) at Dec. 31, 2016				40,436,580	19,810,707	79,610,490	453,066
Balance at beginning of period at Dec. 31, 2016	$ 534,412		$ 145,673	$ 0	$ 0	$ 1	$ 8,358	$ 155,536	$ (1,254)	$ (252)	$ 388,739
Increase (decrease) in stockholder's/members' equity
Share based compensation (in shares)				58,536	(34,019)
Share based compensation	12,314		12,314					12,314
Repurchase of Class C common stock (in shares)					(286,150)
Repurchase of Class C common stock	(4,592)		(4,592)					(4,592)
Treasury stock purchases (in shares)							(8,326)
Treasury stock purchases	(147)		(147)				$ (147)
Net income (loss)	(14,503)		(8,037)						(8,037)		(6,466)
Foreign exchange translation adjustment	8,300		2,848							2,848	5,452
Distribution from Virtu Financial to non-controlling interest	(65,573)										(65,573)
Dividends	(42,013)		(42,013)						(42,013)
Issuance of common stock in connection with employee exchanges (in shares)				1,146,315
Issuance of Class A common stock (in shares)				48,076,924
Issuance of Class A common stock	735,974		735,974	$ 1				735,973
Repurchase of Virtu Financial Units and corresponding number of Class C common stock in connection with employee exchanges (in shares)					(1,146,315)
Issuance of tax receivable agreements in connection with employee exchange	1,355		1,355					1,355
Balance at end of period at Sep. 30, 2017	1,165,527		843,375	$ 1	$ 0	$ 1	$ (8,505)	900,586	(51,304)	2,596	322,152
Balance at end of period (in shares) at Sep. 30, 2017				89,718,355	18,344,223	79,610,490	(461,392)
Balance at beginning period (in shares) at Dec. 31, 2017				90,415,532	17,880,239	79,610,490	(616,923)
Balance at beginning of period at Dec. 31, 2017	1,151,578		830,569	$ 1	$ 0	$ 1	$ (11,041)	900,746	(62,129)	2,991	321,009
Increase (decrease) in stockholder's/members' equity
Share based compensation (in shares)				670,505
Share based compensation	28,708		28,708					28,708
Repurchase of Class C common stock (in shares)					(370,891)
Repurchase of Class C common stock	(8,216)		(8,216)						(8,216)
Treasury stock purchases (in shares)				(664,450)			(1,561,848)
Treasury stock purchases	(58,218)		(58,218)				$ (43,964)		(14,254)
Stock option exercised (in shares)				4,058,673
Stock option exercised	76,754		76,754					76,754
Net income (loss)	472,255		208,573						208,573		263,682
Foreign exchange translation adjustment	(3,713)		(2,270)							(2,270)	(1,443)
Distribution from Virtu Financial to non-controlling interest	(196,061)										(196,061)
Dividends	(74,327)		(74,327)						(74,327)
Issuance of common stock in connection with employee exchanges (in shares)				3,508,217
Issuance of Common Stock in connection with secondary offering, net of offering costs (in shares)				10,518,750		(10,518,750)
Issuance of Common Stock in connection with secondary offering, net of offering costs	(710)		(710)					(710)
Issuance of Class A common stock (in shares)		10,518,750
Repurchase of Virtu Financial Units and corresponding number of Class C common stock in connection with employee exchanges (in shares)					(3,508,217)
Issuance of tax receivable agreements in connection with employee exchange	(3,439)		(3,439)					(3,439)
Balance at end of period at Sep. 30, 2018	$ 1,384,611		$ 997,424	$ 1	$ 0	$ 1	$ (55,005)	$ 1,002,059	$ 49,647	$ 721	$ 387,187
Balance at end of period (in shares) at Sep. 30, 2018				108,507,227	14,001,131	69,091,740	(2,178,771)

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net Income (loss)	$ 472,255	$ (14,503)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,558	29,157
Amortization of purchased intangibles and acquired capitalized software	20,042	6,546
Debt issue cost related to debt refinancing and prepayment	10,645	9,351
Amortization of debt issuance costs and deferred financing fees	7,973	3,470
Termination of office leases	23,300	0
Share based compensation	22,537	10,924
Reserve for legal matters	1,620	(2,176)
Write-down of assets	3,221	1,335
Connectivity early termination	7,062	0
Deferred taxes	8,818	1,489
Gain on sale of businesses	(335,211)	0
Other	69	(444)
Changes in operating assets and liabilities:
Securities borrowed	165,383	101,046
Securities purchased under agreements to resell	(10,014)	8,645
Receivables from broker dealers and clearing organizations	(143,746)	21,241
Trading assets, at fair value	(214,131)	1,020,821
Other assets	112,938	26,248
Securities loaned	45,458	194,523
Securities sold under agreements to repurchase	(89,404)	(220,719)
Payables to broker dealers and clearing organizations	236,138	(393,564)
Trading liabilities, at fair value	13,496	(569,911)
Accounts payable and accrued expenses and other liabilities	(92,496)	(17,708)
Net cash provided by operating activities	313,511	215,771
Cash flows from investing activities
Development of capitalized software	(18,431)	(7,929)
Acquisition of property and equipment	(18,715)	(13,932)
Proceeds from sale of telecommunication assets	600	0
Acquisition of KCG Holdings, net of cash acquired, described in Note 3	0	(799,303)
Acquisition of Teza Technologies	0	(5,594)
Net cash provided by (used in) investing activities	363,646	(826,458)
Cash flows from financing activities
Distribution from Virtu Financial to non-controlling interest	(196,061)	(65,573)
Dividends	(74,327)	(42,013)
Repurchase of stock	(58,218)	(147)
Stock option exercised	76,754	0
Short-term borrowings, net	(15,000)	(10,000)
Proceeds from long-term borrowings	0	1,115,036
Payments on repurchase of non-voting common interest	0	(6,092)
Repayment of long term borrowings	(500,000)	(206,473)
Repayment of KCG Notes	0	(480,987)
Tax receivable agreement obligations	(12,359)	(7,045)
Debt issuance costs	(2,261)	(52,528)
Issuance of common stock, net of offering costs	0	735,973
Issuance of common stock in connection with secondary offering, net of offering costs	(710)	0
Net cash provided by (used in) financing activities	(790,398)	980,151
Effect of exchange rate changes on cash and cash equivalents	(3,713)	8,300
Net increase (decrease) in cash and cash equivalents	(116,954)	377,764
Cash and cash equivalents beginning of period	532,887	181,415
Cash and cash equivalents, end of period	415,933	559,179
Supplementary disclosure of cash flow information
Cash paid for interest	89,102	59,524
Cash paid for taxes	84,337	5,744
Non-cash investing activities
Share based compensation to developers relating to capitalized software	2,055	1,448
Non-cash financing activities
Tax receivable agreement described in Note 6	0	0
Secondary offerings described in Note 16	0	0
Class C
Cash flows from financing activities
Repurchase of stock	(8,216)	0
BondPoint
Cash flows from investing activities
Proceeds from sale of business	400,192	0
DMM Business
Cash flows from investing activities
Proceeds from sale of business	$ 0	$ 300

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Organization The accompanying condensed consolidated financial statements include the accounts and operations of Virtu Financial, Inc. (“VFI” or, collectively with its wholly owned or controlled subsidiaries, the “Company”) beginning with its initial public offering (“IPO”) in April of 2015, along with the historical accounts and operations of Virtu Financial LLC (“Virtu Financial”) prior to the Company’s IPO. VFI is a Delaware corporation whose primary asset is its ownership interest in Virtu Financial, which it acquired pursuant to and subsequent to certain reorganization transactions (the “Reorganization Transactions”) consummated in connection with its IPO. As of September 30, 2018 , VFI owned approximately 56.6% of the membership interests of Virtu Financial. VFI is the sole managing member of Virtu Financial and operates and controls all of the businesses and affairs of Virtu Financial and, through Virtu Financial and its subsidiaries (the “Group”), continues to conduct the business now conducted by such subsidiaries. The Company is a leading financial firm that leverages cutting edge technology to deliver liquidity to the global markets and innovative, transparent market making trading solutions to its clients. The Company has broad diversification, in combination with its proprietary technology platform and low-cost structure, which enables the Company to facilitate risk transfer between global capital markets participants by supplying competitive liquidity and execution services while at the same time earning attractive margins and returns. On July 20, 2017 (the “Closing Date”), the Company completed the all-cash acquisition of KCG Holdings, Inc. (“KCG”) (the “Acquisition of KCG”) . Pursuant to the terms of the Agreement and Plan of Merger, dated as of April 20, 2017 (the “Merger Agreement”), by and among the Company, Orchestra Merger Sub, Inc., a Delaware corporation and an indirect wholly-owned subsidiary of the Company (“Merger Sub”), and KCG Merger Sub merged with and into KCG (the “Merger”), with KCG surviving the Merger as a wholly owned subsidiary of the Company. See Note 3 “Acquisition of KCG Holdings, Inc.” for further details. Virtu Financial’s principal subsidiaries include Virtu Financial BD LLC (“VFBD”), Virtu Americas LLC (“VAL”), and Virtu Financial Capital Markets LLC (“VFCM”, collectively with VFBD and VAL, the "broker-dealers"), which are self-clearing U.S. broker-dealers. Other principal subsidiaries include Virtu Financial Global Markets LLC (“VFGM”), a U.S. trading entity focused on futures and currencies; Virtu Financial Ireland Limited (“VFIL”), formed in Ireland; Virtu Financial Asia Pty Ltd (“VFAP”), formed in Australia; and Virtu Financial Singapore Pte. Ltd. (“VFSing”), formed in Singapore, each of which are trading entities focused on asset classes in their respective geographic regions. On January 2, 2018, the Company completed the sale of its fixed income trading venue, BondPoint, to Intercontinental Exchange (“ICE”) for total gross proceeds of $400.2 million . See Note 4 "Sale of BondPoint" for further details. Prior to the Acquisition of KCG, the Company was managed and operated as one business, under one operating segment. As a result of the Acquisition of KCG, beginning in the third quarter of 2017 the Company has three operating segments: (i) Market Making; (ii) Execution Services; and (iii) Corporate. See Note 19 "Geographic Information and Business Segments" for a further discussion of the Company’s segments. Basis of Consolidation and Form of Presentation These condensed consolidated financial statements are presented in U.S. dollars, have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding financial reporting with respect to Form 10-Q and accounting standards generally accepted in the United States of America (“U.S. GAAP”) promulgated in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC” or the “Codification”), and reflect all adjustments that, in the opinion of management, are normal and recurring, and that are necessary for a fair statement of the results for the periods presented. The condensed consolidated financial statements are unaudited and should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 (the “2017 Form 10-K”). The condensed consolidated financial statements of the Company include its equity interests in Virtu Financial and its subsidiaries. The Company operates and controls all business and affairs of Virtu Financial and its operating subsidiaries indirectly through its equity interest in Virtu Financial. Certain reclassifications have been made to the prior periods’ condensed consolidated financial statements in order to conform to the current period presentation. Such reclassifications are immaterial, individually and in the aggregate, to both current and all previously issued financial statements taken as a whole and have no effect on previously reported condensed consolidated net income available to common stockholders. The condensed consolidated financial statements include the accounts of the Company and its majority and wholly owned subsidiaries. As sole managing member of Virtu Financial, the Company exerts control over the Group’s operations. The Company consolidates Virtu Financial and its subsidiaries’ financial statements and records the interests in Virtu Financial that the Company does not own as noncontrolling interests. All intercompany accounts and transactions have been eliminated in consolidation. As discussed in Note 3 “Acquisition of KCG Holdings Inc.”, the Company has accounted for the acquisition of KCG under the acquisition method of accounting. Under the acquisition method of accounting, the assets and liabilities of KCG, as of the Closing Date, were recorded at their respective fair values and added to the carrying value of the Company's existing assets and liabilities. The reported financial condition, results of operations and cash flows of the Company for the periods following the Acquisition reflect KCG's and the Company's balances, and reflect the impact of purchase accounting adjustments. The financial results for the three and nine months ended September 30, 2017 comprise the results of the Company for the entire applicable period and results of KCG from Closing Date through September 30, 2017. All periods to the Closing Date comprise solely results of the Company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates The Company's condensed consolidated financial statements are prepared in conformity with U.S. GAAP, which require management to make estimates and assumptions regarding measurements including the fair value of trading assets and liabilities, goodwill and intangibles, compensation accruals, capitalized software, income tax, and other matters that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accordingly, actual results could differ materially from those estimates. Earnings Per Share Earnings per share (“EPS”) is calculated on both a basic and diluted basis. Basic EPS excludes dilution and is calculated by dividing income available to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted EPS is calculated by dividing the net income available for common stockholders by the diluted weighted average shares outstanding for that period. Diluted EPS includes the determinants of the basic EPS and, in addition, reflects the dilutive effect of shares of common stock estimated to be distributed in the future under the Company’s share based compensation plans. The Company grants restricted stock units (“RSUs”), which entitle recipients to receive nonforfeitable dividends during the vesting period on a basis equivalent to the dividends paid to holders of common stock. As a result, the unvested RSUs meet the definition of a participating security requiring the application of the two-class method. Under the two-class method, earnings available to common shareholders, including both distributed and undistributed earnings, are allocated to each class of common stock and participating securities according to dividends declared and participating rights in undistributed earnings, which may cause diluted EPS to be more dilutive than the calculation using the treasury stock method. Cash and Cash Equivalents Cash and cash equivalents include money market accounts, which are payable on demand, and short-term investments with an original maturity of less than 90 days. The Company maintains cash in bank deposit accounts that, at times, may exceed federally insured limits. The Company manages this risk by selecting financial institutions deemed highly creditworthy to minimize the risk. Securities Borrowed and Securities Loaned The Company conducts securities borrowing and lending activities with external counterparties. In connection with these transactions, the Company receives or posts collateral, which comprises cash and/or securities. In accordance with substantially all of its stock borrow agreements, the Company is permitted to sell or repledge the securities received. Securities borrowed or loaned are recorded based on the amount of cash collateral advanced or received. The initial cash collateral advanced or received generally approximates or is greater than 102% of the fair value of the underlying securities borrowed or loaned. The Company monitors the fair value of securities borrowed and loaned, and delivers or obtains additional collateral as appropriate. Receivables and payables with the same counterparty are not offset in the condensed consolidated statements of financial condition. Interest received or paid by the Company for these transactions is recorded gross on an accrual basis under interest and dividends income or interest and dividends expense in the condensed consolidated statements of comprehensive income. Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase In a repurchase agreement, securities sold under agreements to repurchase are treated as collateralized financing transactions and are recorded at contract value, plus accrued interest, which approximates fair value. It is the Company's policy that its custodian take possession of the underlying collateral securities with a fair value approximately equal to the principal amount of the repurchase transaction, including accrued interest. For reverse repurchase agreements, the Company typically requires delivery of collateral with a fair value approximately equal to the carrying value of the relevant assets in the condensed consolidated statements of financial condition. To ensure that the fair value of the underlying collateral remains sufficient, the collateral is valued daily with additional collateral obtained or excess collateral returned, as permitted under contractual provisions. The Company does not net securities purchased under agreements to resell transactions with securities sold under agreements to repurchase transactions entered into with the same counterparty. The Company has entered into bilateral and tri-party term and overnight repurchase and other collateralized financing agreements which bear interest at negotiated rates. The Company receives cash and makes delivery of financial instruments to a custodian who monitors the market value of these instruments on a daily basis. The market value of the instruments delivered must be equal to or in excess of the principal amount loaned under the repurchase agreements plus the agreed upon margin requirement. The custodian may request additional collateral, if appropriate. Interest received or paid by the Company for these transactions is recorded gross on an accrual basis under interest and dividends income or interest and dividends expense in the condensed consolidated statements of comprehensive income. Receivables from/Payables to Broker-dealers and Clearing Organizations As of September 30, 2018 and December 31, 2017 , receivables from and payables to broker-dealers and clearing organizations primarily represented amounts due for unsettled trades, open equity in futures transactions, securities failed to deliver or failed to receive, deposits with clearing organizations or exchanges and balances due from or due to prime brokers in relation to the Company’s trading. Amounts receivable from broker-dealers and clearing organizations may be restricted to the extent that they serve as deposits for securities sold, not yet purchased. The Company presents its balances, including outstanding principal balances on all credit facilities, on a net by counterparty basis within receivables from and payables to broker-dealers and clearing organizations when the criteria for offsetting are met. In the normal course of business, a significant portion of the Company’s securities transactions, money balances, and security positions are transacted with several third-party brokers. The Company is subject to credit risk to the extent any broker with whom it conducts business is unable to fulfill contractual obligations on its behalf. The Company monitors the financial condition of such brokers and to minimize the risk of any losses from these counterparties. Financial Instruments Owned Including Those Pledged as Collateral and Financial Instruments Sold, Not Yet Purchased Financial instruments owned and Financial instruments sold, not yet purchased relate to market making and trading activities, and include listed and other equity securities, listed equity options and fixed income securities. The Company records financial instruments owned, including those pledged as collateral, and financial instruments sold, not yet purchased at fair value. Gains and losses arising from financial instrument transactions are recorded net on a trade-date basis in trading income, net, in the condensed consolidated statements of comprehensive income. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or would be paid to transfer a liability (i.e., the exit price) in an orderly transaction between market participants at the measurement date. Fair value measurements are not adjusted for transaction costs. The recognition of “block discounts” for large holdings of unrestricted financial instruments where quoted prices are readily and regularly available in an active market is prohibited. The Company categorizes its financial instruments into a three level hierarchy which prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy level assigned to each financial instrument is based on the assessment of the transparency and reliability of the inputs used in the valuation of such financial instruments at the measurement date based on the lowest level of input that is significant to the fair value measurement. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurement) and the lowest priority to unobservable inputs (level 3 measurements). Financial instruments measured and reported at fair value are classified and disclosed in one of the following categories based on inputs: Level 1 — Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 — Quoted prices in markets that are not active and financial instruments for which all significant inputs are observable, either directly or indirectly; or Level 3 — Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. Transfers in or out of levels are recognized based on the beginning fair value of the period in which they occurred. Fair Value Option The fair value option election allows entities to make an irrevocable election of fair value as the initial and subsequent measurement attribute for certain eligible financial assets and liabilities. Unrealized gains and losses on items for which the fair value option has been elected are recorded in other, net in the condensed consolidated statements of comprehensive income. The decision to elect the fair value option is determined on an instrument by instrument basis, which must be applied to an entire instrument and is irrevocable once elected. Derivative Instruments Derivative instruments are used for trading purposes, including economic hedges of trading instruments, are carried at fair value, and include futures, forward contracts, and options. Gains or losses on these derivative instruments are recognized currently within trading income, net in the condensed consolidated statement of comprehensive income. Fair values for exchange-traded derivatives, principally futures, are based on quoted market prices. Fair values for over-the-counter derivative instruments, principally forward contracts, are based on the values of the underlying financial instruments within the contract. The underlying instruments are currencies, which are actively traded. The Company presents its derivatives balances on a net-by-counterparty basis when the criteria for offsetting are met. Cash flows associated with such derivative activities are included in cash flows from operating activities on the condensed consolidated statements of cash flows. Property, Equipment and Occupancy Property and equipment are carried at cost, less accumulated depreciation, except for the assets acquired in connection with acquisitions using the purchase accounting method, which were recorded at fair value on the respective date of acquisitions. Depreciation is provided using the straight-line method over estimated useful lives of the underlying assets. Routine maintenance, repairs and replacement costs are expensed as incurred and improvements that appreciably extend the useful life of the assets are capitalized. When property and equipment are sold or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in income. Property and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the related carrying amount may not be recoverable. Furniture, fixtures, and equipment are depreciated over three to seven years. Leasehold improvements are amortized over the lesser of the life of the improvement or the term of the lease. The Company recognizes rent expense under operating leases with fixed rent escalations, lease incentives and free rent periods on a straight-line basis over the lease term beginning on the date the Company takes possession of or controls the use of the space, including during free rent periods. Lease Loss Accrual The Company’s policy is to identify excess real estate capacity and where applicable, accrue for related future costs, net of projected sub-lease income upon the date the Company ceases to use the excess real estate, which is recorded under operating and administrative in the condensed consolidated statements of comprehensive income. Such accrual is adjusted to the extent the actual terms of sub-leased property differ from the previous assumptions used in the calculation of the accrual. Capitalized Software The Company capitalizes costs of materials, consultants, and payroll and payroll related costs for employees incurred in developing internal-use software. Costs incurred during the preliminary project and post-implementation stages are charged to expense. Management’s judgment is required in determining the point at which various projects enter the stages at which costs may be capitalized, in assessing the ongoing value of the capitalized costs, and in determining the estimated useful lives over which the costs are amortized. Capitalized software development costs and related accumulated amortization are included in property, equipment and capitalized software in the accompanying condensed consolidated statements of financial condition and are amortized over a period of 1.5 to 2.5 years , which represents the estimated useful lives of the underlying software. Goodwill Goodwill represents the excess of the purchase price over the underlying net tangible and intangible assets of the Company’s acquisitions. Goodwill is not amortized but is tested for impairment on an annual basis and between annual tests whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Goodwill is tested at the reporting unit level, which is defined as an operating segment or one level below the operating segment. The Company tests goodwill for impairment on an annual basis on July 1 and on an interim basis when certain events or circumstances exist. In the impairment test as of July 1, 2018, the Company assessed qualitative factors as described in ASC 350-20 for each of its reporting units for any indicators that the fair values of the reporting units were less than their carrying values. Intangible Assets The Company amortizes finite-lived intangible assets over their estimated useful lives. Finite-lived intangible assets are tested for impairment when impairment indicators are present, and if impaired, they are written down to fair value. Exchange Memberships and Stock Exchange memberships are recorded at cost or, if any other than temporary impairment in value has occurred, at a value that reflects management’s estimate of fair value. Exchange memberships acquired in connection with the Acquisition were recorded at their fair value on the date of acquisition. Exchange stock includes shares that entitle the Company to certain trading privileges. The Company’s exchange memberships and stock are included in intangibles in the condensed consolidated statements of financial condition. Trading Income, net Trading income, net is comprised of changes in the fair value of trading assets and liabilities (i.e., unrealized gains and losses) and realized gains and losses on trading assets and liabilities. Trading gains and losses on financial instruments owned and financial instruments sold, not yet purchased are recorded on the trade date and reported on a net basis in the condensed consolidated statements of comprehensive income. Commissions, net and Technology Services Commissions, net, which primarily comprise commissions and commission equivalents earned on institutional client orders, are recorded on a trade date basis. Under a commission management program, the Company allows institutional clients to allocate a portion of their gross commissions to pay for research and other services provided by third parties. The Company recognizes the related revenue when the third party research services are rendered and payments are made. As the Company acts as an agent in these transactions, it records such expenses on a net basis within commissions and technology services in the condensed consolidated statements of comprehensive income. Technology services revenues consist of technology licensing fees and agency commission fees. Technology licensing fees are earned from third parties for licensing of the Company’s proprietary risk management and trading infrastructure technology and the provision of associated management and hosting services. These fees include both upfront and annual recurring fees, as well as, in certain cases, contingent fees based on client revenues, which represent variable consideration. The services offered under these contracts have the same pattern of transfer; accordingly, they are being measured and recognized as a single performance obligation. The performance obligation is satisfied over time, and accordingly, revenue is recognized as time passes. Variable consideration has not been included in the transaction price as the amount of consideration is contingent on factors outside the Company’s control and thus it is not probable that a significant reversal of cumulative revenue recognized will not occur. Recurring fees, which exclude variable consideration, are billed and collected on a quarterly basis. Interest and Dividends Income/Interest and Dividends Expense Interest income and interest expense are accrued in accordance with contractual rates. Interest income consists of interest earned on collateralized financing arrangements and on cash held by brokers. Interest expense includes interest expense from collateralized transactions, margin and related lines of credit. Dividends on financial instruments owned including those pledged as collateral and financial instruments sold, not yet purchased are recorded on the ex-dividend date and interest is recognized on an accrual basis. Brokerage, Exchange and Clearance Fees, Net Brokerage, exchange and clearance fees, net, comprise the costs of executing and clearing trades and are recorded on a trade date basis. Rebates consist of volume discounts, credits or payments received from exchanges or other market places related to the placement and/or removal of liquidity from the order flow in the marketplace. Rebates are recorded on an accrual basis and included net within brokerage, exchange and clearance fees in the accompanying condensed consolidated statements of comprehensive income. Payments for Order Flow Payments for order flow represent payments to broker-dealer clients, in the normal course of business, for directing their order flow in U.S. equities to the Company. Payments for order flow are recorded on a trade-date basis in the condensed consolidated statements of comprehensive income. Income Taxes Subsequent to consummation of the Reorganization Transactions and the IPO, the Company is subject to U.S. federal, state and local income taxes on its taxable income. The Company's subsidiaries are subject to income taxes in the respective jurisdictions (including foreign jurisdictions) in which they operate. Prior to the consummation of the Reorganization Transactions and the IPO, no provision for United States federal, state and local income tax was required, as Virtu Financial is a limited liability company and is treated as a pass-through entity for United States federal, state, and local income tax purposes. The provision for income tax is comprised of current tax and deferred tax. Current tax represents the tax on current year tax returns, using tax rates enacted at the balance sheet date. The deferred tax assets are recognized in full and then reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be recognized. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the applicable taxing authority, including resolution of the appeals or litigation processes, based on the technical merits of the position. The tax benefits recognized in the condensed consolidated financial statements from such a position are measured based on the largest benefit for each such position that has a greater than fifty percent likelihood of being realized upon ultimate resolution. Many factors are considered when evaluating and estimating the tax positions and tax benefits. Such estimates involve interpretations of regulations, rulings, case law, etc. and are inherently complex. The Company’s estimates may require periodic adjustments and may not accurately anticipate actual outcomes as resolution of income tax treatments in individual jurisdictions typically would not be known for several years after completion of any fiscal year. Comprehensive Income and Foreign Currency Translation Comprehensive income consists of two components: net income and other comprehensive income (“OCI”). The Company’s OCI is comprised of foreign currency translation adjustments. Assets and liabilities of operations having non-U.S. dollar functional currencies are translated at period-end exchange rates, and revenues and expenses are translated at weighted average exchange rates for the period. Gains and losses resulting from translating foreign currency financial statements, net of related tax effects, are reflected in accumulated other comprehensive income, a separate component of stockholders’ equity. The Company's foreign subsidiaries generally use the U.S. dollar as their functional currency. The Company also has subsidiaries that utilize a functional currency other than the U.S. dollar, primarily comprising its subsidiaries domiciled in Ireland, which utilizes the Euro as the functional currency. The Company may seek to reduce the impact of fluctuations in foreign exchange rates on its net investment in certain non-U.S. operations through the use of foreign currency forward contracts. For foreign currency forward contracts designated as hedges, the Company assesses its risk management objectives and strategy, including identification of the hedging instrument, the hedged item and the risk exposure and how effectiveness is to be assessed prospectively and retrospectively. The effectiveness of the hedge is assessed based on the overall changes in the fair value of the forward contracts. For qualifying net investment hedges, any gains or losses, to the extent effective, are included in Accumulated other comprehensive income on the condensed consolidated statements of financial condition and Cumulative translation adjustment, net of tax, on the condensed consolidated statements of comprehensive income. The ineffective portion, if any, is recorded in investment income and other, net on the condensed consolidated statements of operations. Share-Based Compensation The fair value of awards issued for compensation prior to the Reorganization Transactions and the IPO was determined by management, with the assistance of an independent third party valuation firm, using a projected annual forfeiture rate, where applicable, on the date of grant. Share-based awards issued for compensation in connection with or subsequent to the Reorganization Transactions and the IPO pursuant to the VFI 2015 Management Incentive Plan (as amended, the “2015 Amended and Restated Management Incentive Plan”) were in the form of stock options, Class A common stock and RSUs. The fair value of the stock option grants is determined through the application of the Black-Scholes-Merton model. The fair value of the Class A common stock and RSUs are determined based on the volume weighted average price for the three days preceding the grant, and with respect to the RSUs, a projected annual forfeiture rate. The fair value of share-based awards granted to employees is expensed based on the vesting conditions and are recognized on a straight line basis over the vesting period. The Company records as treasury stock shares repurchased from its employees for the purpose of settling tax liabilities incurred upon the issuance of Class A common stock, the vesting of RSUs or the exercise of stock options. Variable Interest Entities A variable interest entity (“VIE”) is an entity that lacks one or more of the following characteristics (i) the total equity investment at risk is sufficient to enable the entity to finance its activities independently and (ii) the equity holders have the power to direct the activities of the entity that most significantly impact its economic performance, the obligation to absorb the losses of the entity and the right to receive the residual returns of the entity. The Company will be considered to have a controlling financial interest and will consolidate a VIE if it has both (i) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. In October 2016, the Company invested in a joint venture (“JV”) with nine other parties. One of the parties was KCG. Upon the Merger, KCG was required to relinquish their ownership in the JV. As of September 30, 2018 , each of the remaining parties owns approximately 11% of the voting shares and 11% of the equity of this JV. In addition, as a result of the Acquisition of KCG, the Company owns 50% of the voting shares and 50% of the equity of another JV. These two JVs build and maintain microwave communication networks in the U.S., Europe, and Asia. The Company and its JV partners each pay monthly fees for the use of the microwave communication networks in connection with their respective trading activities, and the JVs may sell excess bandwidth that is not utilized by the JV members to third parties. The JVs meet the criteria to be considered VIEs. In each of the JVs, the Company does not have the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance; therefore it does not have a controlling financial interest in and does not consolidate the JVs. The Company records its interest in each JV under the equity method of accounting and records its investment in the JVs within Other assets and its amounts payable for communication services provided by the JV within Accrued expenses and other liabilities on the condensed consolidated statements of financial condition. The Company records its pro-rata share of each JV's earnings or losses within Other, net and fees related to the use of communication services provided by the JVs within Communications and data processing on the condensed consolidated statements of comprehensive income. The Company’s exposure to the obligations of these VIEs is generally limited to its interests in each respective JV, which is the carrying value of the equity investment in each JV. The following table presents the Company’s nonconsolidated VIEs at September 30, 2018 : Carrying Amount Maximum Exposure to Loss VIEs' assets (in thousands) Asset Liability Equity investment $ 18,669 $ — $ 18,669 $ 48,557 The following table presents the Company’s nonconsolidated VIEs at December 31, 2017 : Carrying Amount Maximum Exposure to Loss VIEs' assets (in thousands) Asset Liability Equity investment $ 18,799 $ — $ 18,799 $ 41,936 Accounting Pronouncements, Recently Adopted Revenue Recognition - In May 2014, the FASB issued Accounting Standard Update (“ASU”) 2014-9, Revenue from Contracts with Customers . ASU 2014-9 is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. ASU 2014-9 also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The Company adopted the new revenue standard on January 1, 2018 by applying the modified retrospective method, which did not result in a transition adjustment. The new standard does not apply to revenue associated with financial instruments that are accounted for under other U.S. GAAP, and as a result, did not have a material impact on the Company’s condensed consolidated financial statements, which are most closely associated with financial instruments, including trading income, net, and interest and dividends income. The new revenue standard primarily impacts revenues from technology services, commissions and soft-dollar arrangements generated by execution services. The additional disclosures required by the new standard have been included in Note 13 "Revenues from Contracts with Customers" . Financial Assets and Liabilities — In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The ASU affects the accounting for equity investments, financial liabilities under fair value option and presentation and disclosure requirements of financial instruments. The ASU affects all entities that hold financial assets or owe financial liabilities and is effective for annual reporting periods (including interim periods) beginning after December 15, 2017. The Company does not currently classify any equity securities as available for sale, and it does not apply the fair value option to its own debt issuances. The Company has adopted this ASU as of January 1, 2018, and it did not have a material impact on its condensed consolidated financial statements. Income Taxes – In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 749): Intra-Entity Transfers of Assets Other Than Inventory . The ASU requires the reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of the transactions are eliminated in consolidation. Any deferred tax asset that arises in the buyer’s jurisdiction would also be recognized at the time of the transfer. The ASU is effective for reporting periods beginning after December 15, 2017. The Company adopted this ASU on January 1, 2018, and it did not have a material impact on its condensed consolidated financial statements. Business Combinations - In January 2017, the FASB issued ASU 2017-1, Business Combinations (Topic 805), Clarifying the Definition of a Business , to amend the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The ASU is effective for reporting periods beginning after December 15, 2017. The Company adopted this ASU on January 1, 2018, and it did not have a material impact on its condensed consolidated financial statements. Accounting Pronouncements, Not Yet Adopted as of September 30, 2018 Leases — In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . Under the new ASU, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. The liability will be equal to the present value of the future lease payments. The asset, referred to as a “right-of-use asset” will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, leases will be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting, but without explicit bright lines. The Company's implementation effort is ongoing, and it will adopt this ASU on January 1, 2019. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to

Acquisition of KCG Holdings, In

Acquisition of KCG Holdings, Inc.	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisition of KCG Holdings, Inc.	Acquisition of KCG Holdings, Inc. As of the Closing Date of the Acquisition of KCG, each of KCG’s issued and outstanding shares of Class A common stock, par value $0.01 per share was cancelled and extinguished and converted into the right to receive $20.00 in cash, without interest, less any applicable withholding taxes. On the Closing Date, and in connection with the financing of the Acquisition of KCG, as described in Note 10 "Borrowings" , the Company issued to Aranda Investments Pte. Ltd. (“Aranda”), an affiliate of Temasek Holdings (Private) Limited (“Temasek”), 6,346,155 shares of the Company’s Class A common stock, pursuant to the investment agreement with Aranda (as amended, the “Aranda Investment Agreement”) for an aggregate purchase price of approximately $99.0 million . On August 10, 2017, the Company issued an additional 1,666,666 shares of its Class A common stock for an aggregate purchase price of $26.0 million (collectively, the “Temasek Investment”). On the Closing Date, and in connection with the financing of the Acquisition of KCG, the Company issued to North Island Holdings I, LP (“NIH”) 39,725,979 shares of the Company’s Class A common stock for an aggregate purchase price of approximately $613.5 million . On August 10, 2017 the Company issued an additional 338,124 shares of its Class A common stock for an aggregate purchase price of $5.2 million (collectively, the “NIH Investment”). In connection with the Temasek Investment and NIH Investment, the Company incurred approximately $7.8 million in fees which were recorded as a reduction to additional paid-in capital. On July 21, 2017, the outstanding 6.875% Senior Secured Notes due 2020 issued by KCG were redeemed at a redemption price equal to 103.438% of the $465.0 million principal amount, plus accrued and unpaid interest. The redemption was pursuant to the indenture, dated as of March 13, 2015 (as amended, restated, supplemented or otherwise modified), by and among KCG, the subsidiary guarantors party thereto and The Bank of New York Mellon, as trustee and collateral agent. See "Fourth Amended and Restated Credit Agreement" and "Senior Secured Second Lien Notes" in Note 10 "Borrowings" . Accounting treatment of the acquisition The Acquisition of KCG has been accounted for as a purchase of KCG by the Company, pursuant to provisions of ASC 805, Business Combinations . Under the acquisition method of accounting, the assets and liabilities of KCG, as of July 20, 2017, were recorded at their respective fair values and added to the carrying value of the Company's existing assets and liabilities. These fair values were determined with the assistance of third party valuation professionals. The reported financial condition, results of operations and cash flows of the Company for the periods following the Acquisition of KCG reflect KCG’s and the Company's balances and reflect the impact of purchase accounting adjustments. Purchase price and goodwill The aggregate cash purchase price of $1.4 billion was determined as the sum of the fair value, at $20.00 per share, of KCG shares and warrants outstanding to former KCG stockholders at closing and the fair value of KCG employee stock based awards that were outstanding, and which vested at the Closing Date. The purchase price has been allocated to the assets acquired and liabilities assumed using their estimated fair values at the Closing Date of the Acquisition of KCG. Adjustments to the provisional values during the measurement period were recorded in the reporting period in which the adjustment amounts were determined. No further adjustments to the provisional values remain. The Company engaged third party specialists for the purchase price allocation. Amounts allocated to intangible assets, the amortization period and goodwill were as follows: (in thousands) Amount Amortization Years Technology $ 67,700 1-6 years Customer relationships 94,000 13 - 17 years Trade names 1,000 10 years Favorable leases 5,895 2-15 years Exchange memberships 6,400 Indefinite Intangible assets $ 174,995 Goodwill 128,286 Total $ 303,281 Of the total Goodwill of $128.3 million , $96.2 million has been assigned to the Market Making segment and $32.1 million has been assigned to the Execution Services segment. Such goodwill is attributable to the expansion of products offerings and expected synergies of the combined workforce, products and technologies of the Company and KCG. Tax treatment of the Acquisition The Company believes that the Acquisition of KCG will be treated as a tax-free transaction to the Company that does not result in a step up in tax basis in the acquired assets and, therefore, KCG’s tax basis in its assets and liabilities generally carries over to the Company following the Acquisition of KCG. None of the goodwill is expected to be deductible for tax purposes. The Company recorded net deferred tax assets of $23.9 million with respect to recording KCG’s assets and liabilities under the purchase method of accounting as described above as well as recording the value of other tax attributes acquired as a result of the Acquisition of KCG, as described in Note 14 "Income Taxes" .

Sale of BondPoint

Sale of BondPoint	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Sale of BondPoint	Sale of BondPoint In October 2017, the Company entered into an Asset Purchase Agreement (the “BondPoint Agreement”) with Intercontinental Exchange ("ICE") pursuant to which the Company has agreed to sell specified assets and to assign specified liabilities constituting its BondPoint division and fixed income venue (“BondPoint”). BondPoint is a provider of electronic fixed income trading solutions for the buy-side and sell-side offering access to centralized liquidity and automated trade execution services. As of December 31, 2017, the Company transferred the carrying value of BondPoint to assets held for sale; refer to Note 4 “Business held for sale” in the 2017 Form 10-K. On January 2, 2018, the Company completed the sale of BondPoint to ICE for total gross proceeds of $400.2 million in cash. The Company incurred one-time transaction costs of $8.5 million , which include professional fees of $7.1 million related to the sale and $1.4 million of compensation expense, which is recorded in Transaction advisory fees and expenses and Employee compensation and payroll taxes , respectively, on the condensed consolidated statement of comprehensive income. The Company recognized a gain on sale of $337.6 million , which is recorded in Other, net on the condensed consolidated statement of comprehensive income for the nine months ended September 30, 2018 . A summary of the carrying value of BondPoint and gain on sale of BondPoint is as follows: (in thousands) Total sale proceeds received $ 400,192 Business assets and liabilities held for sale as of December 31, 2017: Receivables from broker dealers and clearing organizations 3,383 Intangibles and other assets 51,687 Liabilities (728 ) Total carrying value of BondPoint as of December 31, 2017: 54,342 Goodwill adjustment allocated to BondPoint 8,300 Gain on sale of BondPoint 337,550 Transaction costs 8,568 Gain on sale of BondPoint, net of transaction costs $ 328,982

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The below table contains a reconciliation of net income before noncontrolling interest to net income available for common stockholders: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Income (loss) before income taxes and noncontrolling interest $ 29,425 $ (46,495 ) $ 547,585 $ (17,421 ) Provision for (benefit from) income taxes 13,815 (6,505 ) 75,330 (2,918 ) Net income 15,610 (39,990 ) 472,255 (14,503 ) Noncontrolling interest (6,998 ) 26,472 (263,682 ) 6,466 Net income (loss) available for common stockholders $ 8,612 $ (13,518 ) $ 208,573 $ (8,037 ) The calculation of basic and diluted earnings per share is presented below: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except for share or per share data) 2018 2017 2018 2017 Basic earnings per share: Net income (loss) available for common stockholders $ 8,612 $ (13,518 ) $ 208,573 $ (8,037 ) Less: Dividends and undistributed earnings allocated to participating securities (418 ) (314 ) (4,029 ) (997 ) Net income (loss) available for common stockholders, net of dividends and undistributed earnings allocated to participating securities 8,194 (13,832 ) 204,544 (9,034 ) Weighted average shares of common stock outstanding: Class A 106,692,034 79,199,142 99,038,084 53,520,346 Basic earnings per share $ 0.08 $ (0.17 ) $ 2.07 $ (0.17 ) Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except for share or per share data) 2018 2017 2018 2017 Diluted earnings per share: Net income (loss) available for common stockholders, net of dividends and undistributed earnings allocated to participating securities $ 8,194 $ (13,832 ) $ 204,544 $ (9,034 ) Weighted average shares of common stock outstanding: Class A Issued and outstanding 106,692,034 79,199,142 99,038,084 53,520,346 Issuable pursuant to 2015 Management Incentive Plan (1) 436,172 — 1,430,776 — 107,128,206 79,199,142 100,468,860 53,520,346 Diluted earnings per share $ 0.08 $ (0.17 ) $ 2.04 $ (0.17 ) (1) The dilutive impact of unexercised stock options excludes from the computation of EPS 1,578,617 and 1,704,307 options for the three and nine months ended September 30, 2017 , respectively, because inclusion of the options would have been anti-dilutive.

Tax Receivable Agreements

Tax Receivable Agreements	9 Months Ended
	Sep. 30, 2018
Tax Receivable Agreements [Abstract]
Tax Receivable Agreements	Tax Receivable Agreements In connection with the IPO and the Reorganization Transactions, the Company entered into tax receivable agreements to make payments to certain Virtu pre-IPO equityholders ("Virtu Members") that are generally equal to 85% of the applicable cash tax savings, if any, that the Company actually realizes as a result of favorable tax attributes that were and will continue to be available to the Company as a result of the Reorganization Transactions, exchanges of membership interests for Class A common stock or Class B common stock and payments made under the tax receivable agreements. Payments will occur only after the filing of the U.S. federal and state income tax returns and realization of the cash tax savings from the favorable tax attributes. The Company made its first payment of $7.0 million in February 2017 and its second payment of $12.3 million in September 2018. As a result of (i) the purchase of equity interests in Virtu Financial from certain Virtu Members in connection with the Reorganization Transactions, (ii) the purchase of non-voting common interest units in Virtu Financial (the “Virtu Financial Units”) (along with the corresponding shares of Class C common stock) from certain of the Virtu Members in connection with the IPO, (iii) the purchase of Virtu Financial Units (along with the corresponding shares of Class C common stock) and the exchange of Virtu Financial Units (along with the corresponding shares of Class C common stock) for shares of Class A common stock in connection with the secondary offerings completed in September 2016, November 2015, and May 2018 (the “Secondary Offerings”), payments to certain Virtu Members in respect of the purchases are expected to range from approximately $3.6 million to $16.0 million per year over the next 15 years . The corresponding deduction to additional paid-in capital was approximately $16.4 million for the difference between the tax receivable agreements liability and the related deferred tax asset. In connection with the May 2018 secondary offering, as described in Note 16 "Capital Structure" , the Company recorded an additional deferred tax asset of $61.1 million and payment liability pursuant to the tax receivable agreements of $64.6 million , with the $3.5 million difference recorded as a decrease to additional paid-in capital. As a result of the reduction in the U.S. corporate income tax rate as described below, the aforementioned deferred tax asset and related payment liability were subsequently reduced as described below. The amounts recorded as of September 30, 2018 are based on best estimates available at the respective dates and may be subject to change after the filing of the Company’s U.S. federal and state income tax returns for the years in which tax savings were realized. The 2017 Tax Act includes, among other items, a permanent reduction to the U.S. corporate income tax rate from 35% to 21% effective January 1, 2018 as further described in Note 14 "Income Taxes" . As a result, at December 31, 2017 , the Company recorded a reduction of its tax receivable agreement obligation of $86.6 million . As further described in Note 14 "Income Taxes" , the Company also recorded a reduction of its deferred tax assets, including the deferred tax assets described above. At September 30, 2018 and December 31, 2017 , the Company’s remaining deferred tax assets described above were approximately $153.9 million and $101.6 million , respectively, and the Company’s liabilities over the next 15 years pursuant to the tax receivable agreements are approximately $199.3 million and $147.0 million , respectively. For the tax receivable agreements discussed above, the cash savings realized by the Company are computed by comparing the actual income tax liability of the Company to the amount of such taxes the Company would have been required to pay had there been (i) no increase to the tax basis of the assets of Virtu Financial as a result of the purchase or exchange of Virtu Financial Units, (ii) no tax benefit from the tax basis in the intangible assets of Virtu Financial on the date of the IPO and (iii) no tax benefit as a result of the Net Operating Losses (“NOLs”) and other tax attributes of Virtu Financial. Subsequent adjustments of the tax receivable agreements obligations due to certain events (e.g., changes to the expected realization of NOLs or changes in tax rates) will be recognized within income before taxes and noncontrolling interests in the condensed consolidated statements of comprehensive income.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Prior to the Acquisition of KCG, the Company was managed and operated as one business, and accordingly, operated under one operating segment. As a result of the Acquisition of KCG, beginning in the third quarter of 2017 the Company has three operating segments: (i) Market Making; (ii) Execution Services; and (iii) Corporate. The Company allocated goodwill to the new reporting units using a relative fair value approach. In addition, the Company performed an assessment of potential goodwill impairment for all reporting units immediately prior to the reallocation and determined that no impairment was indicated. The following table presents the details of goodwill by segment: (in thousands) Market Making Execution Services Corporate Total Balance as of December 31, 2017 $ 755,292 $ 89,591 $ — $ 844,883 Goodwill adjustment allocated to BondPoint — (8,300 ) — (8,300 ) Balance as of September 30, 2018 $ 755,292 $ 81,291 $ — $ 836,583 As of September 30, 2018 and December 31, 2017 , the Company’s total amount of goodwill recorded was $836.6 million and $844.9 million , respectively. As described in Note 4 "Sale of BondPoint" , the Company allocated $8.3 million of goodwill to BondPoint as part of the sale. No goodwill impairment was recognized during the nine months ended September 30, 2018 and 2017 . Acquired intangible assets consisted of the following as of September 30, 2018 and December 31, 2017 : As of September 30, 2018 (in thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Useful Lives (Years) Purchased technology $ 110,000 $ 110,000 $ — 1.4 to 2.5 ETF issuer relationships 950 638 312 9 ETF buyer relationships 950 639 311 9 Technology 60,000 25,382 34,618 1 to 6 Customer relationships 49,000 4,885 44,115 12 Favorable occupancy leases 5,895 1,020 4,875 3 to 15 Exchange memberships 5,838 — 5,838 Indefinite $ 232,633 $ 142,564 $ 90,069 As of December 31, 2017 (in thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Useful Lives Purchased technology $ 110,000 $ 110,000 $ — 1.4 to 2.5 ETF issuer relationships 950 559 391 9 ETF buyer relationships 950 559 390 9 Leases 1,800 397 1,403 3 FCC licenses 200 19 181 7 Technology 60,000 9,644 50,356 1 to 6 Customer relationships 49,000 1,822 47,178 12 Favorable occupancy leases 5,895 408 5,487 3 to 15 Exchange memberships 5,838 — 5,838 Indefinite $ 234,633 $ 123,408 $ 111,224 Amortization expense relating to finite-lived intangible assets was approximately $6.4 million for each of the three months ended September 30, 2018 , and 2017 , and approximately $20.0 million and $6.5 million for the nine months ended September 30, 2018 and 2017 , respectively. This is included in amortization of purchased intangibles and acquired capitalized software in the accompanying condensed consolidated statements of comprehensive income. In the third quarter of 2018, the Company sold certain assets to one of its joint ventures, including the intangible assets associated with leases with a net carrying value of $1.1 million at the time of sale.

Receivables from_Payables to Br

Receivables from/Payables to Broker-Dealers and Clearing Organizations	9 Months Ended
	Sep. 30, 2018
Due to and from Broker-Dealers and Clearing Organizations [Abstract]
Receivables from/Payables to Broker-Dealers and Clearing Organizations	Receivables from/Payables to Broker-Dealers and Clearing Organizations The following is a summary of receivables from and payables to brokers-dealers and clearing organizations at September 30, 2018 and December 31, 2017 : (in thousands) September 30, 2018 December 31, 2017 Assets Due from prime brokers $ 370,599 $ 219,573 Deposits with clearing organizations 95,817 112,847 Net equity with futures commission merchants 260,705 203,711 Unsettled trades with clearing organization 150,265 173,778 Securities failed to deliver 229,944 248,088 Commissions and fees 8,434 14,021 Total receivables from broker-dealers and clearing organizations $ 1,115,764 $ 972,018 Liabilities Due to prime brokers $ 398,181 $ 197,439 Net equity with futures commission merchants 53,986 44,526 Unsettled trades with clearing organization 470,665 420,029 Securities failed to receive 28,077 51,143 Commissions and fees 1,434 3,068 Total payables to broker-dealers and clearing organizations $ 952,343 $ 716,205 Included as a deduction from “Due from prime brokers” and “Net equity with futures commission merchants” is the outstanding principal balance on all of the Company’s short-term credit facilities (described in Note 10 "Borrowings" ) of approximately $144.7 million and $205.7 million as of September 30, 2018 and December 31, 2017 , respectively. The loan proceeds from the credit facilities are available only to meet the initial margin requirements associated with the Company’s ordinary course futures and other trading positions, which are held in the Company’s trading accounts with an affiliate of the respective financial institutions. The credit facilities are fully collateralized by the Company’s trading accounts and deposit accounts with these financial institutions. “Securities failed to deliver” and “Securities failed to receive” include amounts with a clearing organization and other broker-dealers.

Collateralized Transactions

Collateralized Transactions	9 Months Ended
	Sep. 30, 2018
Collateralized Agreements [Abstract]
Collateralized Transactions	Collateralized Transactions The Company is permitted to sell or repledge securities received as collateral and use these securities to secure repurchase agreements, enter into securities lending transactions or deliver these securities to counterparties or clearing organizations to cover short positions. At September 30, 2018 and December 31, 2017 , substantially all of the securities received as collateral have been repledged. The fair value of the collateralized transactions at September 30, 2018 and December 31, 2017 are summarized as follows: (in thousands) September 30, 2018 December 31, 2017 Securities received as collateral: Securities borrowed $ 1,261,472 $ 1,415,793 Securities purchased under agreements to resell 10,014 — $ 1,271,486 $ 1,415,793 In the normal course of business, the Company pledges qualified securities with clearing organizations to satisfy daily margin and clearing fund requirements. Financial instruments owned and pledged, where the counterparty has the right to repledge, at September 30, 2018 and December 31, 2017 consisted of the following: (in thousands) September 30, 2018 December 31, 2017 Equities $ 542,088 $ 586,251 U.S. and Non-U.S. government obligations — 99 Exchange traded notes 10,541 8,693 $ 552,629 $ 595,043

Borrowings

Borrowings	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Borrowings	Borrowings Broker-Dealer Credit Facilities The Company is a party to two secured credit facilities with a financial institution to finance overnight securities positions purchased as part of its ordinary course broker-dealer market making activities. One of the facilities (the “Uncommitted Facility”), is provided on an uncommitted basis collateralized by one of the Company’s broker-dealer subsidiaries trading and deposit account with the financial institution. On November 3, 2017, the Company entered the second credit facility (“Revolving Credit Facility”) with the same financial institution for an aggregated borrowing limit of $500.0 million . The Revolving Credit Facility consists two borrowing bases: Borrowing Base A Loan is to be used to finance the purchase and settlement of securities; Borrowing Base B Loan is to be used to fund margin deposit with the NSCC. Each of the three broker-dealers has a sublimit under Borrowing Base A Loan, from $25 million to $500 million , which bears interest at the adjusted LIBOR or base rate plus 1.25% per annum. Two out of the three broker-dealers have a sublimit under Borrowing Base B Loan, from $40 million to $100 million , which bears interest at the adjusted LIBOR or base rate plus 2.50% per annum. A commitment fee of 0.50% per annum on the average daily unused portion of this facility is payable quarterly in arrears. The following summarizes the Company’s broker-dealer credit facilities' carrying values, net of unamortized debt issuance costs, where applicable: At September 30, 2018 (in thousands) Interest Rate Financing Available Borrowing Outstanding Deferred Debt Issuance Cost Outstanding Borrowings, net Broker-dealer credit facilities: Uncommitted facility 3.17% $ 200,000 $ 10,000 $ (1,081 ) $ 8,919 Revolving credit facility 3.51% 500,000 7,000 (1,352 ) 5,648 $ 700,000 $ 17,000 $ (2,433 ) $ 14,567 At December 31, 2017 (in thousands) Interest Rate Financing Available Borrowing Outstanding Deferred Debt Issuance Cost Outstanding Borrowings, net Broker-dealer credit facilities: Uncommitted facility 2.42% $ 150,000 $ 25,000 $ — $ 25,000 Revolving credit facility 2.81% 500,000 7,000 (4,117 ) 2,883 $ 650,000 $ 32,000 $ (4,117 ) $ 27,883 The following summarizes interest expense for the broker-dealer facilities. Interest expense is included within interest and dividends expense in the accompanying condensed consolidated statements of comprehensive income. Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Broker-dealer credit facilities: Uncommitted facility $ 428 $ 405 $ 1,458 $ 1,335 Committed facility (1) — 2 — 33 Revolving credit facility 60 — 212 — $ 488 $ 407 $ 1,670 $ 1,368 (1) Facility was terminated in July 2017. Short-Term Credit Facilities The Company maintains short-term credit facilities with various prime brokers and other financial institutions from which it receives execution or clearing services. The proceeds of these facilities are used to meet margin requirements associated with the products traded by the Company in the ordinary course, and amounts borrowed are collateralized by the Company’s trading accounts with the applicable financial institution. At September 30, 2018 Weighted Average Financing Borrowing Short-Term Credit Facilities: Short-term credit facilities (2) 4.27% $ 566,000 $ 144,660 $ 566,000 $ 144,660 At December 31, 2017 Weighted Average Interest Rate Financing Available Borrowing Outstanding Short-Term Credit Facilities: Short-term credit facilities (2) 3.86% $ 543,000 $ 205,677 $ 543,000 $ 205,677 (2) Outstanding borrowings were included with receivable from/ payable to broker-dealers and clearing organization within the condensed consolidated statements of financial condition. Interest expense in relation to the facilities was approximately $1.5 million and $1.4 million for the three months ended September 30, 2018 and 2017 , respectively, and $5.0 million and $4.8 million for the nine months ended September 30, 2018 , and 2017 . Long-Term Borrowings The following summarizes the Company’s long-term borrowings, net of unamortized discount and debt issuance costs, where applicable: At September 30, 2018 (in thousands) Maturity Interest Outstanding Principal Discount Deferred Debt Issuance Cost Outstanding Borrowings, net Long-term borrowings: Fourth Amended and Restate Credit Agreement December 2021 5.09% $ 400,000 $ (360 ) $ (7,267 ) $ 392,373 Senior secured Second Lien Notes June 2022 6.75% 500,000 — (19,099 ) 480,901 SBI bonds January 2020 5.00% 30,783 — (30 ) 30,753 $ 930,783 $ (360 ) $ (26,396 ) $ 904,027 At December 31, 2017 (in thousands) Maturity Date Interest Rate Outstanding Principal Discount Deferred Debt Issuance Cost Outstanding Borrowings, net Long-term borrowings: Fourth Amended and Restate Credit Agreement December 2021 5.13% $ 900,000 $ (999 ) $ (18,504 ) $ 880,497 Senior secured Second Lien Notes June 2022 6.75% 500,000 — (22,961 ) 477,039 SBI bonds January 2020 5.00% 31,059 — (47 ) 31,012 $ 1,431,059 $ (999 ) $ (41,512 ) $ 1,388,548 Fourth Amended and Restated Credit Agreement To finance the Acquisition, on June 30, 2017, Virtu Financial and VFH Parent LLC (“VFH”) entered into a fourth amended and restated credit agreement (as amended on January 2, 2018 and September 19, 2018, the “Fourth Amended and Restated Credit Agreement”) with the lenders party thereto and JPMorgan Chase Bank, N.A., as administrative agent, sole lead arranger and bookrunner, which amended and restated in its entirety the existing Credit Agreement, and upon the closing of the Acquisition of KCG, provided for an aggregate $1.15 billion of first lien secured term loans (the “Term Loan Facility”). For the nine months ended September 30, 2018 , $500.0 million of prepayments were made under the Fourth Amended and Restated Credit Agreement, for an aggregate total of $750.0 million of principal prepayments under the Term Loan Facility since its closing. As a result of these prepayments, the total principal outstanding under the senior secured credit facility is $400.0 million . VFH also entered into a repricing transaction during January 2018 to reprice the senior secured term loans under the Fourth Amended and Restated Credit Agreement at LIBOR plus 3.25% , and another repricing transaction during September 2018 to reprice such senior secured term loans at LIBOR plus 2.75% . In connection with the debt refinancing and the debt prepayment, the Company accelerated approximately $11.7 million for unamortized financing costs incurred that were scheduled to be amortized over the term of the loan, including original issue discount and underwriting and legal fees, which is included within debt issue cost related to debt refinancing in the consolidated statements of comprehensive income. The Fourth Amended and Restated Credit Agreement contains certain customary covenants and certain customary events of default, including relating to a change of control. If an event of default occurs and is continuing, the lenders under the Fourth Amended and Restated Credit Agreement will be entitled to take various actions, including the acceleration of amounts outstanding under the Fourth Amended and Restated Credit Agreement and all actions permitted to be taken by a secured creditor in respect of the collateral securing the obligations under the Fourth Amended and Restated Credit Agreement. Senior Secured Second Lien Notes To finance the Acquisition of KCG, on June 16, 2017, the Escrow Issuer and Orchestra Co-Issuer, Inc. (the “Co-Issuer”) completed the offering of $500.0 million aggregate principal amount of 6.750% Senior Secured Second Lien Notes due 2022 (the “Notes”). The Notes were issued under an Indenture, dated June 16, 2017 (the “Indenture”), among the Escrow Issuer, the Co-Issuer and U.S. Bank National Association, as trustee and collateral agent. On July 20, 2017, VFH assumed all of the obligations of the Escrow Issuer under the Indenture and the Notes. The Notes are guaranteed by Virtu Financial and each of Virtu Financial’s wholly-owned domestic restricted subsidiaries that guarantees the Fourth Amended and Restated Credit Agreement. The Indenture imposes certain limitations on the Company, and contains certain customary events of default, including, among others, payment defaults related to the failure to pay principal or interest on the Notes, covenant defaults, final maturity default or cross-acceleration with respect to material indebtedness and certain bankruptcy events. The gross proceeds from the Notes were deposited into a segregated escrow account with an escrow agent. The proceeds were released from escrow as of the Closing Date and were used to finance, in part, the Acquisition of KCG, and to repay certain indebtedness of the Company and KCG. (See Note 3 “Acquisition of KCG Holdings, Inc.” for further details). SBI Bonds On July 25, 2016, VFH issued Japanese Yen Bonds (collectively the “SBI Bonds”) in the aggregate principal amount of ¥3.5 billion ( $33.1 million at issuance date) to SBI Life Insurance Co., Ltd. and SBI Insurance Co., Ltd. The proceeds from the SBI Bonds were used to partially fund the investment in SBI (as described in Note 11 “Financial assets and liabilities”). The SBI Bonds are guaranteed by Virtu Financial. The SBI Bonds are subject to fluctuations on the Japanese Yen currency rates relative to the Company’s reporting currency (U.S. Dollar) with the changes reflected in other, net in the condensed consolidated statements of comprehensive income. The principal balance was ¥3.5 billion ( $30.8 million ) as of September 30, 2018 and ¥3.5 billion ( $31.1 million ) as of December 31, 2017 . The Company recorded losses of $0.9 million and $0.3 million due to the change in currency rates during the three and nine months ended September 30, 2018 . Losses due to the change in currency rates were immaterial for the three and nine months ended September 30, 2017 . Aggregate future required minimum principal payments based on the terms of the long-term borrowings were as follows: (in thousands) September 30, 2018 2018 $ — 2019 — 2020 30,783 2021 and thereafter 900,000 Total principal of long-term borrowings $ 930,783

Financial Assets and Liabilitie

Financial Assets and Liabilities	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities	Financial Assets and Liabilities Financial Instruments Measured at Fair Value The fair value of equities, options, on the run U.S. government obligations and exchange traded notes is estimated using recently executed transactions and market price quotations in active markets and are categorized as Level 1 with the exception of inactively traded equities and certain other financial instruments, which are categorized as Level 2. The Company’s corporate bonds, derivative contracts and other U.S. and non-U.S. government obligations have been categorized as Level 2. Fair value of the Company’s derivative contracts is based on the indicative prices obtained from broadly distributed bank and broker dealers, as well as management’s own analyses. The indicative prices have been independently validated through the Company’s risk management systems, which are designed to check prices with information independently obtained from exchanges and venues where such financial instruments are listed or to compare prices of similar instruments with similar maturities for listed financial futures in foreign exchange. As of March 31, 2017, the Company began pricing certain financial instruments held for trading at fair value based on theoretical prices, which can differ from quoted market prices. The theoretical prices reflect price adjustments primarily caused by the fact that the Company continuously prices its financial instruments based on all available information. This information includes prices for identical and near-identical positions, as well as the prices for securities underlying the Company’s positions, on other exchanges that are open after the exchange on which the financial instruments is traded closes. The Company validates that all price adjustments can be substantiated with market inputs and checks the theoretical prices independently. Consequently, such financial instruments are classified as Level 2. The Company concluded that this is a change in accounting estimate and no retrospective adjustments were necessary. There were no transfers of financial instruments between levels during the three and nine months ended September 30, 2018 and 2017 . Fair value measurements for those items measured on a recurring basis are summarized below as of September 30, 2018 : September 30, 2018 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Counterparty and Cash Collateral Netting Total Fair Value Assets Financial instruments owned, at fair value: Equity securities $ 814,667 $ 1,286,236 $ — $ — $ 2,100,903 U.S. and Non-U.S. government obligations 92,965 21,375 — — 114,340 Corporate Bonds — 68,965 — — 68,965 Exchange traded notes 13,042 48,369 — — 61,411 Currency forwards — 1,929,452 — (1,901,746 ) 27,706 Options 799 — — — 799 921,473 3,354,397 — (1,901,746 ) 2,374,124 Financial instruments owned, pledged as collateral: Equity securities $ 386,731 $ 155,357 $ — $ — $ 542,088 U.S. and Non-U.S. government obligations — — — — — Exchange traded notes 2,790 7,751 — — 10,541 389,521 163,108 — — 552,629 Other Assets Equity investment $ — $ — $ 40,243 $ — $ 40,243 Exchange stock 2,132 — — — 2,132 2,132 — 40,243 — 42,375 Liabilities Financial instruments sold, not yet purchased, at fair value: Equity securities $ 1,092,602 $ 1,162,905 $ — $ — $ 2,255,507 U.S. and Non-U.S. government obligations 82,916 1,227 — — 84,143 Corporate Bonds — 37,865 — — 37,865 Exchange traded notes 874 19,012 — — 19,886 Currency forwards — 1,942,686 — (1,942,686 ) — Options 693 — — — 693 $ 1,177,085 $ 3,163,695 $ — $ (1,942,686 ) $ 2,398,094 Fair value measurements for those items measured on a recurring basis are summarized below as of December 31, 2017 : December 31, 2017 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Counterparty and Cash Collateral Netting Total Fair Value Assets Financial instruments owned, at fair value: Equity securities $ 758,596 $ 1,167,995 $ — $ — $ 1,926,591 Non-U.S. government obligations 5,968 16,815 — — 22,783 Corporate Bonds — 60,975 — — 60,975 Exchange traded notes 13,576 68,819 — — 82,395 Currency forwards — 2,045,487 — (2,027,697 ) 17,790 Options 7,045 — — — 7,045 $ 785,185 $ 3,360,091 $ — $ (2,027,697 ) $ 2,117,579 Financial instruments owned, pledged as collateral: Equity securities $ 410,670 $ 175,581 $ — $ — $ 586,251 U.S. and Non-U.S. government obligations 99 — — — 99 Exchange traded notes 82 8,611 — — 8,693 $ 410,851 $ 184,192 $ — $ — $ 595,043 Other Assets Equity investment $ — $ — $ 40,588 $ — $ 40,588 Exchange stock 1,952 — — — 1,952 Other (1) — 55,824 — — 55,824 $ 1,952 $ 55,824 $ 40,588 $ — $ 98,364 Liabilities Financial instruments sold, not yet purchased, at fair value: Equity securities $ 847,816 $ 1,355,616 $ — $ — $ 2,203,432 U.S. and Non-U.S. government obligations 18,940 12,481 — — 31,421 Corporate Bonds — 81,118 — — 81,118 Exchange traded notes 1,514 54,248 — — 55,762 Currency forwards — 2,032,017 — (2,024,991 ) 7,026 Options 5,839 — — — 5,839 $ 874,109 $ 3,535,480 $ — $ (2,024,991 ) $ 2,384,598 (1) Other primarily consists of a $55.8 million receivable from Bats related to the sale of KCG Hotspot. SBI Investment As of September 30, 2018 , the fair value of SBI Investment was determined using the discounted cash flow method, an income approach, with the discount rate of 15.0% applied to the cash flow forecasts. The Company also used a market approach based on 14 x average price/earnings multiples of comparable companies to corroborate the income approach. The fair value of the SBI Investment at September 30, 2018 was determined by taking the weighted average of enterprise valuations based on discounted cash flow on projected income from the next five years , the implied enterprise valuations on comparable companies, and the implied enterprise valuations on comparable transactions. The fair value measurement is highly sensitive to significant changes in the unobservable inputs and significant increases (decreases) in discount rate or decreases (increases) in price/earnings multiples would result in a significantly lower (higher) fair value measurement. Changes in the fair value of the SBI Investment are reflected in other, net in the condensed consolidated statements of comprehensive income. Receivable from Bats Global Markets, Inc. (“Bats”) In March 2015, KCG sold KCG Hotspot, an institutional spot foreign exchange electronic communications networks (“ECN”), to Bats, which is now a subsidiary of CBOE Holdings, Inc. KCG and Bats agreed to share certain tax benefits, which comprise a $50.0 million payment and an annual payment of up to $6.6 million , both of which were paid to the Company in April 2018. Financial Instruments Not Measured at Fair Value The table below presents the carrying value, fair value and fair value hierarchy category of certain financial instruments that are not measured at fair value on the condensed consolidated statement of financial condition. The table below excludes non-financial assets and liabilities. The carrying value of financial instruments not measured at fair value categorized in the fair value hierarchy as Level 1 and Level 2 approximates fair value due to the relatively short-term nature of the underlying assets. The fair value of the Company’s long-term borrowings is categorized as Level 2 in the fair value hierarchy, which is based on quoted prices from the market. The table below summarizes financial assets and liabilities not carried at fair value on a recurring basis as of September 30, 2018 : September 30, 2018 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Carrying Value Fair Value (Level 1) (Level 2) (Level 3) Assets Cash and cash equivalents $ 415,933 $ 415,933 $ 415,933 $ — $ — Securities borrowed 1,305,789 1,305,789 — 1,305,789 — Securities purchased under agreements to resell 10,014 10,014 — 10,014 — Receivables from broker dealers and clearing organizations 1,115,764 1,115,764 225,274 890,490 — Total Assets $ 2,847,500 $ 2,847,500 $ 641,207 $ 2,206,293 $ — Liabilities Short-term borrowings $ 14,567 $ 14,567 $ — $ 14,567 $ — Long-term borrowings 904,027 950,685 — 950,685 — Securities loaned 800,145 800,145 — 800,145 — Securities sold under agreements to repurchase 301,238 301,238 — 301,238 — Payables to broker dealer and clearing organizations 952,343 952,343 277,486 674,859 — Total Liabilities $ 2,972,320 $ 3,018,978 $ 277,486 $ 2,741,494 $ — The table below summarizes financial assets and liabilities not carried at fair value on a recurring basis as of December 31, 2017 : December 31, 2017 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Carrying Value Fair Value (Level 1) (Level 2) (Level 3) Assets Cash and cash equivalents $ 532,887 $ 532,887 $ 532,887 $ — $ — Securities borrowed 1,471,172 1,471,172 — 1,471,172 — Receivables from broker dealers and clearing organizations 972,018 972,018 36,513 935,505 — Total Assets $ 2,976,077 $ 2,976,077 $ 569,400 $ 2,406,677 $ — Liabilities Short-term borrowings $ 27,883 $ 27,883 $ — $ 27,883 $ — Long-term borrowings 1,388,548 1,465,489 — 1,465,489 — Securities loaned 754,687 754,687 — 754,687 — Securities sold under agreements to repurchase 390,642 390,642 — 390,642 — Payables to broker dealer and clearing organizations 716,205 716,205 2,925 713,280 — Total Liabilities $ 3,277,965 $ 3,354,906 $ 2,925 $ 3,351,981 $ — The following presents the changes in Level 3 financial instruments measured at fair value on a recurring basis: Nine Months Ended September 30, 2018 (in thousands) December 31, 2017 Purchases Total Realized and Unrealized Gains / (Losses) Net Transfers into (out of) Level 3 Settlement September 30, 2018 Change in Net Unrealized Gains / (Losses) on Investments still held at September 30, 2018 Assets Other assets: Equity investment $ 40,588 $ — $ (345 ) $ — $ — $ 40,243 $ (345 ) Total $ 40,588 $ — $ (345 ) $ — $ — $ 40,243 $ (345 ) Nine Months Ended September 30, 2017 (in thousands) December 31, 2016 Purchases Total Realized and Unrealized Gains / (Losses) Net Transfers into (out of) Level 3 Settlement September 30, 2017 Change in Net Unrealized Gains / (Losses) on Investments still held at September 30, 2017 Assets Other assets: Equity investment $ 36,031 $ — $ 1,232 $ — $ — $ 37,263 $ 1,232 Other — 3,000 — — — 3,000 — Total $ 36,031 $ 3,000 $ 1,232 $ — $ — $ 40,263 $ 1,232 Offsetting of Financial Assets and Liabilities The Company does not net securities borrowed and securities loaned, or securities purchased under agreements to resell and securities sold under agreements to repurchase. These financial instruments are presented on a gross basis in the condensed consolidated statements of financial condition. In the tables below, the amounts of financial instruments owned that are not offset in the condensed consolidated statements of financial condition, but could be netted against financial liabilities with specific counterparties under legally enforceable master netting agreements in the event of default, are presented to provide financial statement readers with the Company’s estimate of its net exposure to counterparties for these financial instruments. The following tables set forth the gross and net presentation of certain financial assets and financial liabilities as of September 30, 2018 and December 31, 2017 : September 30, 2018 Gross Amounts of Recognized Assets Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Received Net Amount Offsetting of Financial Assets: Securities borrowed $ 1,305,789 $ — $ 1,305,789 $ (1,268,772 ) $ (6,195 ) $ 30,822 Securities purchased under agreements to resell 10,014 — 10,014 (9,993 ) (21 ) — Trading assets, at fair value: Currency forwards 1,929,452 (1,901,746 ) 27,706 — — 27,706 Options 799 — 799 (799 ) — — Total $ 3,246,054 $ (1,901,746 ) $ 1,344,308 $ (1,279,564 ) $ (6,216 ) $ 58,528 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Pledged Net Amount Offsetting of Financial Liabilities: Securities loaned $ 800,145 $ — $ 800,145 $ (786,922 ) $ (6,195 ) $ 7,028 Securities sold under agreements to repurchase 301,238 — $ 301,238 (301,220 ) (21 ) (3 ) Trading liabilities, at fair value: Currency forwards 1,942,686 (1,942,686 ) — — — Options 693 — 693 (693 ) — — Total $ 3,044,762 $ (1,942,686 ) $ 1,102,076 $ (1,088,835 ) $ (6,216 ) $ 7,025 December 31, 2017 Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Received Net Amount Offsetting of Financial Assets: Securities borrowed $ 1,471,172 $ — $ 1,471,172 $ (1,418,672 ) $ (13,318 ) $ 39,182 Trading assets, at fair value: Currency forwards 2,045,487 (2,027,697 ) 17,790 — — 17,790 Options 7,045 — 7,045 (45 ) — 7,000 Total $ 3,523,704 $ (2,027,697 ) $ 1,496,007 $ (1,418,717 ) $ (13,318 ) $ 63,972 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Pledged Net Amount Offsetting of Financial Liabilities: Securities loaned $ 754,687 $ — $ 754,687 $ (737,731 ) $ (10,776 ) $ 6,180 Securities sold under agreements to repurchase 390,642 — 390,642 (390,642 ) — — Trading liabilities, at fair value: Currency forwards 2,032,017 (2,024,991 ) 7,026 — 7,026 Options 5,839 — 5,839 (56 ) — 5,783 Total $ 3,183,185 $ (2,024,991 ) $ 1,158,194 $ (1,128,429 ) $ (10,776 ) $ 18,989 The following table presents gross obligations for securities sold under agreements to repurchase and for securities lending transactions by remaining contractual maturity and the class of collateral pledged: September 30, 2018 Remaining Contractual Maturity (in thousands) Overnight and Continuous Less than 30 days 30 - 60 days 61 - 90 Days Total Repurchase agreements: Equity securities $ — $ 65,000 $ 40,000 $ 160,000 $ 265,000 U.S. and Non-U.S. government obligations 36,238 — — — 36,238 Total $ 36,238 $ 65,000 $ 40,000 $ 160,000 $ 301,238 Securities lending transactions: Equity securities $ 800,145 $ — $ — $ — $ 800,145 Total $ 800,145 $ — $ — $ — $ 800,145 December 31, 2017 Remaining Contractual Maturity (in thousands) Overnight and Continuous Less than 30 days 30 - 60 days 61 - 90 Days Total Repurchase agreements: Equity securities $ — $ 100,000 $ 90,000 $ 200,000 $ 390,000 U.S. and Non-U.S. government obligations 642 — — — 642 Total $ 642 $ 100,000 $ 90,000 $ 200,000 $ 390,642 Securities lending transactions: Equity securities $ 754,687 $ — $ — $ — $ 754,687 Total $ 754,687 $ — $ — $ — $ 754,687

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The fair value of the Company’s derivative instruments on a gross basis consisted of the following at September 30, 2018 and December 31, 2017 : (in thousands) September 30, 2018 December 31, 2017 Derivatives Assets Financial Statements Location Fair Value Notional Fair Value Notional Derivative instruments not designated as hedging instruments: Equities futures Receivables from broker dealers and clearing organizations $ 16,357 $ 3,398,419 $ (505 ) $ 1,985,770 Commodity futures Receivables from broker dealers and clearing organizations 225,449 12,830,011 971 21,231,001 Currency futures Receivables from broker dealers and clearing organizations 21,986 2,672,739 26,548 3,994,412 Fixed income futures Receivables from broker dealers and clearing organizations — 34,186 73 44,395 Options Financial instruments owned 799 139,046 7,045 682,369 Currency forwards Financial instruments owned 1,929,452 138,790,533 2,045,487 124,000,221 Derivatives Liabilities Financial Statements Location Fair Value Notional Fair Value Notional Derivative instruments not designated as hedging instruments: Equities futures Payables to broker dealers and clearing organizations $ (1,687 ) $ 127,500 $ (575 ) $ 142,658 Commodity futures Payables to broker dealers and clearing organizations (276,827 ) 6,058,850 (1,602 ) 130,042 Currency futures Payables to broker dealers and clearing organizations 359 2,566,892 (13,947 ) 7,756,958 Fixed income futures Payables to broker dealers and clearing organizations 1,039 54,534 (1 ) 2,584 Options Financial instruments sold, not yet purchased 693 140,079 5,839 681,147 Currency forwards Financial instruments sold, not yet purchased 1,942,686 138,797,150 2,032,017 123,993,234 Derivative instruments designated as hedging instruments: Currency forwards Financial instruments sold, not yet purchased — — (514 ) 16,115 Amounts included in receivables from and payables to broker-dealers and clearing organizations represent net variation margin on long and short futures contracts. The following table summarizes the net gain from derivative instruments not designated as hedging instruments under ASC 815, which are recorded in trading income, net, and from those designated as hedging instrument under ASC 815, which are recorded in accumulated other comprehensive income in the accompanying condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 2018 and 2017 . Three Months Ended September 30, Nine Months Ended September 30, (in thousands) Financial Statements Location 2018 2017 2018 2017 Derivative instruments not designated as hedging instruments: Futures Trading income, net $ 103,950 $ 35,097 $ (325,556 ) $ 249,274 Currency forwards Trading income, net (47,882 ) 8,950 148,706 3,135 Options Trading income, net 1,161 21,120 (7,575 ) 21,119 Others Trading income, net — 125 — — $ 57,229 $ 65,292 $ (184,425 ) $ 273,528 Derivative instruments designated as hedging instruments: Foreign exchange - forward contract Accumulated other comprehensive income $ 699 $ 19 $ 855 $ 19

Revenues from Contracts with Cu

Revenues from Contracts with Customers	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenues from Contracts with Customers	Revenues from Contracts with Customers Revenue Recognition The Company adopted ASC Topic 606, Revenue from Contracts with Customers as of January 1, 2018 in the condensed consolidated financial statements by applying the modified retrospective method. The Company’s revenue recognition methods for its contracts with customers prior to the adoption of Topic 606 are consistent with its methods after the adoption of Topic 606. Accordingly, the adoption of the new standard did not result in a transition adjustment to opening retained earnings, and as a result, revenues for contracts with customers would not have been adjusted in prior periods and are not presented herein on an adjusted basis. The new revenue guidance does not apply to revenue associated with financial instruments, including loans and securities that are accounted for under other U.S. GAAP, and as a result, did not have an impact on the elements of the Company’s condensed consolidated statement of comprehensive income most closely associated with financial instruments, including trading income, net and interest and dividend income. The new standard primarily impacts the presentation of the following revenue streams: • Commissions, net. The Company earns commission revenue by acting as an agent on behalf of customers. The Company’s performance obligations consist of trade execution and clearing services and are satisfied on the trade date; accordingly, commission revenues are recorded on the trade date. Commission revenues are paid on settlement date; therefore, a receivable is recognized as of the trade date. Under a commission management program, the Company allows institutional clients to allocate a portion of their gross commissions to pay for research and other services provided by third parties. As the Company acts as an agent in these transactions, it records such expenses on a net basis within Commissions and technology services in the condensed consolidated statements of comprehensive income. • Technology services. The Company’s technology services revenues consist of technology licensing fees and agency commission fees. Technology licensing fees are earned from third parties for licensing of the Company’s proprietary risk management and trading infrastructure technology and the provision of associated management and hosting services. These fees include both upfront and annual recurring fees as well as, in certain cases, contingent fees based on customer revenues, which represent variable consideration. The services offered under these contracts are delivered as an integrated package and are interdependent and have the same pattern of transfer to the customer; accordingly, the Company measures and recognizes them as a single performance obligation. The performance obligation is satisfied over time, and, therefore, revenue is recognized as time passes. Variable consideration has not been included in the transaction price as the amount of consideration is contingent on factors outside the Company’s control and thus it is not probable that a significant reversal of cumulative revenue recognized will not occur. Recurring fees, which exclude variable consideration, are billed and collected on a quarterly basis and are included within Receivables from broker dealers and clearing organizations. Disaggregation of Revenues The following tables present the Company’s revenue from contracts with customers disaggregated by the services described above, by timing of revenue recognition, reconciled to the Company’s reportable segments, as well as disaggregation of the Company’s revenues by services and geographic region, for the three and nine months ended September 30, 2018 : Three Months Ended September 30, 2018 (in thousands) Market Making Execution Services Corporate Total Revenues from contract with Customers: Commissions, net $ 6,587 $ 33,332 $ — $ 39,919 Technology services — 333 — 333 Total revenue from contract with customers 6,587 33,665 — 40,252 Other sources of revenue 257,783 541 (3,453 ) 254,871 Total Revenues 264,370 34,206 (3,453 ) 295,123 Timing of revenue recognition: Services transferred at a point in time 264,370 33,873 (3,453 ) 294,790 Services transferred over time — 333 — 333 Total Revenues $ 264,370 $ 34,206 $ (3,453 ) $ 295,123 Nine Months Ended September 30, 2018 (in thousands) Market Making Execution Services Corporate Total Revenues from contract with Customers: Commissions, net $ 21,886 $ 113,786 $ — $ 135,672 Technology services — 4,989 — 4,989 Total revenue from contract with customers 21,886 118,775 — 140,661 Other sources of revenue 962,715 339,984 (5,057 ) 1,297,642 Total Revenues 984,601 458,759 (5,057 ) 1,438,303 Timing of revenue recognition: Services transferred at a point in time 984,601 453,770 (5,057 ) 1,433,314 Services transferred over time — 4,989 — 4,989 Total Revenues $ 984,601 $ 458,759 $ (5,057 ) $ 1,438,303 Information on Remaining Performance Obligations and Revenue Recognized As of September 30, 2018 , the aggregate amount of the transaction price allocated to the performance obligations relating to Technology Services revenues that are unsatisfied (or partially unsatisfied) was not material. Contract Assets and Contract Liabilities The timing of the revenue recognition may differ from the timing of payment from customers. The Company records a receivable when revenue is recognized prior to payment, and when the Company has an unconditional right to payment. The Company records a contract liability when payment is received prior to the time at which the satisfaction of the service obligation occurs. We had receivables related to revenues from contracts with customers of $1.7 million and $7.1 million as of September 30, 2018 and December 31, 2017 , respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is subject to U.S. federal, state and local income tax at the rate applicable to corporations less the rate attributable to the noncontrolling interest in Virtu Financial. These noncontrolling interests are subject to U.S. taxation as partnerships. Accordingly, for the three and nine months ended September 30, 2018 and 2017 , the income attributable to these noncontrolling interests is reported in the condensed consolidated statements of comprehensive income, but the related U.S. income tax expense attributable to these noncontrolling interests is not reported by the Company as it is the obligation of the individual partners. The Company’s provisions for (benefits from) income taxes and effective tax rates were $13.8 million and 46.9% , and $(6.5) million and 14.0% for the three months ended September 30, 2018 and 2017 , respectively, and $75.3 million and 13.8% , and $(2.9) million and 16.7% for the nine months ended September 30, 2018 and 2017 , respectively. Income tax expense is also affected by the differing effective tax rates in foreign, state and local jurisdictions where certain of the Company’s subsidiaries are subject to corporate taxation. Included in Other assets on the condensed consolidated statements of financial condition at September 30, 2018 and December 31, 2017 are current income tax receivables of $40.7 million and $115.2 million , respectively. The balance at September 30, 2018 primarily comprises income taxes due to the Company from federal, state and local, and foreign tax jurisdictions based on income before taxes, and the balance at December 31, 2017 primarily comprises the income tax benefit of KCG net operating losses that were generated prior to the Acquisition of KCG and are eligible to be carried back by the Company. Included in Accounts payable and accrued expenses and other liabilities on the condensed consolidated statements of financial condition at September 30, 2018 and December 31, 2017 are current tax liabilities of $16.0 million and $7.6 million , respectively. The balances primarily comprise income taxes owed to federal, state and local, and foreign tax jurisdictions based on income before taxes. Deferred income taxes arise primarily due to the amortization of the deferred tax assets recognized in connection with the IPO ( Note 6 "Tax Receivable Agreements" ) and the Acquisition of KCG ( Note 3 "Acquisition of KCG Holdings, Inc." ), differences in the valuation of financial assets and liabilities, and other temporary differences arising from the deductibility of compensation and depreciation expenses in different time periods for book and income tax return purposes. There are no expiration dates on the deferred tax assets. The Company’s deferred tax asset at September 30, 2018 and December 31, 2017 includes an alternative minimum tax credit carryforward of $0.6 million and $0.6 million , respectively, which can be either refunded over a period of years or applied against future income tax liability pursuant to the 2017 Tax Act. The provisions of ASC 740 require that carrying amounts of deferred tax assets be reduced by a valuation allowance if, based on the available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accordingly, the need to establish valuation allowances for deferred tax assets is assessed periodically with appropriate consideration given to all positive and negative evidence related to the realization of the deferred tax assets. As a result of the Acquisition of KCG, the Company has non-U.S. net operating losses at September 30, 2018 and December 31, 2017 of $231.8 million and $231.8 million , respectively, and has recorded a related deferred tax asset of $43.5 million and $43.5 million , respectively. A full valuation allowance was also recorded against this deferred tax asset at September 30, 2018 and December 31, 2017 as it is more likely than not that this deferred tax asset will not be realized. No valuation allowance against the remaining deferred taxes was recorded as of September 30, 2018 and December 31, 2017 because it is more likely than not that these deferred tax assets will be fully realized. The Company is subject to taxation in U.S. federal, state, local and foreign jurisdictions. As of September 30, 2018 , the Company’s tax years for 2013 through 2017 and 2010 through 2017 are subject to examination by U.S. and non-U.S. tax authorities, respectively. As a result of the Acquisition of KCG, the Company has assumed any KCG tax exposures. KCG is currently subject to U.S. federal income tax examinations for 2013 through 2017, and to non-U.S. income tax examinations for the tax years 2007 through 2017. In addition, the Company is subject to state and local income tax examinations in various jurisdictions for the tax years 2007 through 2017. The final outcome of these examinations is not yet determinable. However, the Company anticipates that adjustments to the unrecognized tax benefits, if any, will not result in a material change to the financial condition, results of operations and cash flows. The 2017 Tax Act was signed into law on December 22, 2017 and significantly revises the U.S. corporate income tax by, among other things, lowering the statutory corporate tax rate from 35% to 21%, and eliminating certain deductions. As of December 31, 2017 , the Company recorded a reduction of its deferred tax assets for the impact of the 2017 Tax Act of approximately $90.6 million , which was primarily composed of the remeasurement of federal net deferred tax assets as a result of the permanent reduction in the U.S. statutory corporate tax rate from 35% to 21%. During the first three quarters of 2018, the Company did not make any further adjustments due to the 2017 Tax Act. The Company has completed its determination of the accounting implications of the 2017 Tax act on its tax balances.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies and Guarantees Legal Proceedings In the ordinary course of business, the nature of the Company’s business subjects it to claims, lawsuits, regulatory examinations or investigations and other proceedings. The Company and its subsidiaries are subject to several of these matters at the present time. Given the inherent difficulty of predicting the outcome of litigation and regulatory matters, particularly in regulatory examinations or investigations or other proceedings in which substantial or indeterminate damages or fines are sought, or where such matters are in the early stages, the Company cannot estimate losses or ranges of losses for such matters where there is only a reasonable possibility that a loss may be incurred. In addition, there are numerous factors that result in a greater degree of complexity in class-action lawsuits as compared to other types of litigation. There can be no assurance that these legal proceedings will not have a material adverse effect on the Company’s results of operations in any future period, and a material judgment, fine or sanction could have a material adverse impact on the Company’s financial condition, results of operations and cash flows. However, it is the opinion of management, after consultation with legal counsel, that, based on information currently available, the ultimate outcome of these matters will not have a material adverse impact on the business, financial condition or operating results of the Company, although they might be material to the operating results for any particular reporting period. The Company carries directors’ and officers’ liability insurance coverage for potential claims, including securities actions, against the Company and its respective directors and officers. In connection with the Acquisition of KCG, a previously filed complaint, which was initially captioned Greenway v. KCG Holdings, Inc., et al., Case No. 2017-421-JTL and filed on behalf of a putative class in Delaware Chancery Court, was recaptioned Chester County Employees’ Retirement Fund v. KCG Holdings, Inc., et al. , amended and refiled on February 14, 2018 to include claims for the alleged breach of fiduciary duties against former KCG board members, claims against each of Virtu and Jefferies for allegedly aiding and abetting the KCG board members’ alleged breaches of fiduciary duty and a claim against Virtu and Jefferies for alleged civil conspiracy. The amended complaint was again amended on July 16, 2018 with the filing of the Verified Second Amended Class Action Complaint (the “Second Amended Complaint”) to include additional factual allegations. No amount of damages is stated in the Second Amended Complaint, against which Virtu intends to defend vigorously. Other Legal and Regulatory Matters The Company owns subsidiaries including regulated entities that are subject to extensive oversight under federal, state and applicable international laws as well as self-regulatory organization ("SRO") rules. Changes in market structure and the need to remain competitive require constant changes to the Company's systems, order routing and order handling procedures. The Company makes these changes while continuously endeavoring to comply with many complex laws and rules. Compliance, surveillance and trading issues common in the securities industry are monitored by, reported to, and/or reviewed in the ordinary course of business by the Company's regulators in the U.S. and abroad. As a major order flow execution destination, the Company is named from time to time in, or is asked to respond to a number of regulatory matters brought by U.S. regulators, foreign regulators, SROs, as well as actions brought by private plaintiffs, which arise from its business activities. There has recently been an increased focus by regulators on Anti-Money Laundering and sanctions compliance by broker-dealers and similar entities, as well as an enhanced interest on suspicious activity reporting and transactions involving microcap securities. In addition, there has been an increased focus by Congress, federal and state regulators, SROs and the media on market structure issues, and in particular, high frequency trading, best execution, internalization, ATS manner of operations, market fragmentation and complexity, colocation, cybersecurity, access to market data feeds and remuneration arrangements, such as payment for order flow and exchange fee structures. The Company has received information requests from various authorities, including the SEC, requesting, among other items, information regarding these market structure matters, to which the Company has responded or is in the process of responding. The Company is currently the subject of various regulatory reviews and investigations by federal, state and foreign regulators and SROs, including the SEC and the Financial Industry Regulatory Authority. In some instances, these matters may rise to a disciplinary action and/or a civil or administrative action. For example, the Autorité des Marchés Financiers ("AMF") fined the Company’s European subsidiary in the amount of €5.0 million (approximately $5.4 million ) based on its allegations that the subsidiary of a predecessor entity engaged in price manipulation and violations of the AMF General Regulation and Euronext Market Rules. The fine was subsequently reduced in 2017 to €3.3 million (approximately $3.9 million ). The Company has fully reserved for the monetary penalty as of September 30, 2018 and anticipates paying the fine during the year ended December 31, 2018. Representations and Warranties; Indemnification Arrangements In the normal course of its operations, the Company enters into contracts that contain a variety of representations and warranties in addition to indemnification obligations. The Company's maximum exposure under these arrangements is currently unknown, as any such exposure could relate to claims not yet brought or events which have not yet occurred. For example, in November 2013, KCG sold Urban Financial of America, LLC ("Urban"), the reverse mortgage origination and securitization business previously owned by Knight Capital Group, Inc., to an investor group now known as Finance of America Reverse , LLC ("FAR"). Pursuant to the terms of the Stock Purchase Agreement between KCG and FAR, Virtu has certain continuing obligations related to KCG's prior ownership of Urban and has been and, in the future may be, advised by FAR of potential claims thereunder. Consistent with standard business practices in the normal course of business, the Company has provided general indemnifications to its managers, officers, directors, employees, and agents against expenses, legal fees, judgments, fines, settlements, and other amounts actually and reasonably incurred by such persons under certain circumstances as more fully disclosed in its operating agreement. The overall maximum amount of the obligations (if any) cannot reasonably be estimated as it will depend on the facts and circumstances that give rise to any future claims.

Capital Structure

Capital Structure	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Capital Structure	Capital Structure The Company has four classes of authorized common stock. The Class A common stock and the Class C common stock have one vote per share. The Class B common stock and the Class D common stock have 10 votes per share. Shares of the Company’s common stock generally vote together as a single class on all matters submitted to a vote of the Company’s stockholders. For details related to the Company's IPO and Reorganization Transactions and other public offerings, refer to Note 15 "Capital Structure" in the Company's 2017 Form 10-K. During the period prior to the Reorganization Transactions and IPO, Class A-2 profits interests and Class B interests were issued to Employee Holdco (as defined below) on behalf of certain key employees and stakeholders. In connection with the Reorganization Transactions, all Class A-2 profits interests and Class B interests were reclassified into non-voting common interest units. As of September 30, 2018 and December 31, 2017 , respectively, there were 9,012,000 and 12,301,067 non-voting common interest units outstanding, respectively, and 3,289,067 and 1,466,484 non-voting common interest units and corresponding Class C common stock were exchanged into Class A common stock, forfeited or repurchased during the nine months ended September 30, 2018 and 2017 , respectively. Amended and Restated 2015 Management Incentive Plan The Company’s board of directors and stockholders adopted the 2015 Management Incentive Plan, which became effective upon consummation of the IPO, and was subsequently amended and restated following receipt of approval from the Company’s stockholders on June 30, 2017. The Amended and Restated 2015 Management Incentive Plan provides for the grant of stock options, restricted stock units, and other awards based on an aggregate of 16,000,000 shares of Class A common stock, subject to additional sublimits, including limits on the total option grant to any one participant in a single year and the total performance award to any one participant in a single year. Acquisition of KCG On the Closing Date and in connection with the financing of the Acquisition of KCG, the Company issued 6,346,155 shares of the Company’s Class A common stock to Aranda for an aggregate purchase price of approximately $99.0 million and 39,725,979 shares of the Company Class A Common Stock to NIH for an aggregate purchase price of approximately $613.5 million . On August 10, 2017, the Company issued an additional 1,666,666 shares of its Class A Common Stock for an aggregate purchase price of $26.0 million and an additional 338,124 shares of its Class A Common Stock for an aggregate purchase price of $5.2 million . See Note 3 "Acquisition of KCG Holdings, Inc." for further details. Share Repurchase Program In February 2018, the Company's board of directors authorized a new share repurchase program of up to $50.0 million in Class A common stock and common units by March 31, 2019. The Company may repurchase shares from time to time in open market transactions, privately negotiated transactions or by other means. Repurchases may also be made under Rule 10b5-1 plans. The timing and amount of repurchase transactions will be determined by the Company's management based on its evaluation of market conditions, share price, legal requirements and other factors. The program may be suspended, modified or discontinued at any time without prior notice. On July 27, 2018, the Company's board of directors authorized the expansion of the Company's share repurchase program, increasing the total authorized amount by $50.0 million to $100.0 million and extending the duration of the program through September 30, 2019. Since the inception of the program in February 2018, the Company has repurchased approximately 2.4 million shares of Class A common stock and common units for approximately $61.9 million . The Company now has approximately $38.1 million remaining capacity for future purchases of shares of Class A common stock and common units under the program. Secondary Offerings In May 2018, the Company and certain selling stockholders completed a public offering (the “May 2018 Secondary Offering”) of 17,250,000 shares of its Class A common stock by the Company and certain selling stockholders at a purchase price per share of $27.16 (the offering price to the public of $28.00 per share minus the underwriters’ discount), which included the exercise in full by the underwriters of their option to purchase additional shares in the May 2018 Secondary Offering. The Company sold 10,518,750 shares of its Class A common stock in the offering, the net proceeds of which were used to purchase an equivalent number of common interest units in Virtu Financial LLC and corresponding shares of Class D common stock from TJMT Holdings LLC pursuant to that certain Member Purchase Agreement, entered into on May 15, 2018 by and between the Company and TJMT Holdings LLC. The selling stockholders sold 6,731,250 shares of Class A common stock in the May 2018 Secondary Offering, including 2,081,250 shares of Class A common stock issued by the Company upon the exercise of vested stock options. Employee Exchanges During the nine months ended September 30, 2018 and 2017 , respectively, pursuant to the exchange agreement by and among the Company, Virtu Financial and holders of Virtu Financial common units, certain current and former employees elected to exchange 3,508,217 and 1,146,315 units, in Virtu Financial held directly or on their behalf by Virtu Employee Holdco LLC (“Employee Holdco”) on a one -for-one basis for shares of Class A common stock. As a result of the completion of the IPO, the Reorganization Transactions, the Secondary Offerings, employee exchanges, and the share issuance in connection with the Acquisition, the Company holds approximately 56.6% interest in Virtu Financial at September 30, 2018 .

Share-based Compensation

Share-based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation	Share-based Compensation Pursuant to 2015 Management Incentive Plan as described in Note 16 "Capital Structure" , and in connection with the IPO, non-qualified stock options to purchase shares of Class A common stock were granted, each of which vests in equal annual installments over a period of the four years from grant date and expires not later than 10 years from the date of grant. The following table summarizes activity related to stock options for the nine months ended September 30, 2018 and 2017 : Options Outstanding Options Exercisable Number of Options Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Life Number of Options Weighted Average Exercise Price Per Share At December 31, 2016 8,234,000 $ 19.00 8.29 2,058,500 $ 19.00 Granted — — — — — Exercised — — — — — Forfeited or expired (401,000 ) — — — — At September 30, 2017 7,833,000 $ 19.00 7.55 3,916,500 $ 19.00 At December 31, 2017 7,783,000 $ 19.00 7.29 3,891,500 $ 19.00 Granted — — — — — Exercised (4,086,558 ) 19.00 — (4,086,558 ) 19.00 Forfeited or expired (83,750 ) — — — — At September 30, 2018 3,612,692 $ 19.00 6.55 1,741,942 $ 19.00 The expected life has been determined based on an average of vesting and contractual period. The risk-free interest rate was determined based on the yields available on U.S. Treasury zero-coupon issues. The expected stock price volatility was determined based on historical volatilities of comparable companies. The expected dividend yield was determined based on estimated future dividend payments divided by the IPO stock price. The Company recognized $1.4 million and $1.4 million for the three months ended September 30, 2018 , and 2017 , respectively, and $4.2 million and $4.2 million for the nine months ended September 30, 2018 , and 2017 , respectively, of compensation expense in relation to the stock options issued and outstanding. As of September 30, 2018 and December 31, 2017 , total unrecognized share-based compensation expense related to unvested stock options was $3.1 million and $7.5 million , respectively, and these amounts are to be recognized over a weighted average period of 0.6 and 1.3 years, respectively. Class A common stock and Restricted Stock Units Pursuant to the 2015 Management Incentive Plan as described in Note 16 "Capital Structure" , subsequent to the IPO, shares of immediately vested Class A common stock and restricted stock units were granted, the latter which vest over a period of up to 4 years . The fair value of the Class A common stock and RSUs was determined based on a volume weighted average price and is being recognized on a straight line basis over the vesting period. For the nine months ended September 30, 2018 , there were 594,536 shares of immediately vested Class A common stock granted as part of 2017 year-end compensation, with a fair value of $11.3 million which was recorded as an increase to the condensed consolidated statements of changes in equity. In addition, the Company accrued compensation expense of $2.5 million and $0.0 million for the three months ended September 30, 2018 and 2017 , respectively, and $7.1 million and $9.4 million for the nine months ended September 30, 2018 and 2017 , respectively, related to immediately vested Class A common stock expected to be awarded as part of year-end incentive compensation, which was included in employee compensation and payroll taxes on the condensed consolidated statements of comprehensive income and accounts payable and accrued expenses and other liabilities on the condensed consolidated statements of financial condition. The following table summarizes activity related to the RSUs: Number of Shares Weighted Average Fair Value At December 31, 2016 1,573,441 $ 18.28 Granted 34,825 17.95 Forfeited (212,729 ) 18.46 Vested (58,536 ) 19.22 At September 30, 2017 1,337,001 18.21 At December 31, 2017 853,047 17.94 Granted 1,265,899 20.89 Forfeited (127,493 ) 18.30 Vested (83,942 ) 18.25 At September 30, 2018 1,907,511 $ 19.86 The Company recognized $4.6 million and $2.2 million for the three months ended September 30, 2018 and 2017 , respectively, and $13.1 million and $7.1 million for the nine months ended September 30, 2018 and 2017 , respectively, of compensation expense in relation to the restricted stock units. As of September 30, 2018 and December 31, 2017 , total unrecognized share-based compensation expense related to unvested RSUs was $25.0 million and $14.3 million , respectively, and this amount is to be recognized over a weighted average period of 1.1 and 1.5 years, respectively.

Regulatory Requirement

Regulatory Requirement	9 Months Ended
	Sep. 30, 2018
Regulatory Capital Requirements [Abstract]
Regulatory Requirement	Regulatory Requirement As of September 30, 2018 and December 31, 2017 , broker-dealer subsidiaries of the Company are subject to the SEC Uniform Net Capital Rule 15c3-1, which requires the maintenance of minimum net capital of $1.0 million for each of the three broker-dealers. Pursuant to NYSE and NYSE MKT (formerly NYSE Amex) rules, VAL was also required to maintain $3.1 million and $4.1 million of capital in connection with the operation of its designated market maker (“DMM”) business as of September 30, 2018 and December 31, 2017 , respectively. The required amount is determined under the exchange rules as the greater of $1 million or 15% of the market value of 60 trading units for each symbol in which the broker-dealer subsidiary is registered as the DMM. This DMM business was transferred from VFCM to VAL during the second quarter of 2018. The regulatory capital and regulatory capital requirements of these subsidiaries as of September 30, 2018 were as follows: (in thousands) Regulatory Capital Regulatory Capital Requirement Excess Regulatory Capital Virtu Americas LLC $ 337,534 $ 4,086 $ 333,448 Virtu Financial BD LLC 82,546 1,000 81,546 Virtu Financial Capital Markets LLC 9,020 1,000 8,020 The regulatory capital and regulatory capital requirements of these subsidiaries as of December 31, 2017 were as follows: (in thousands) Regulatory Capital Regulatory Capital Requirement Excess Regulatory Capital Virtu Americas LLC $ 379,875 $ 1,000 $ 378,875 Virtu Financial BD LLC 40,683 1,000 39,683 Virtu Financial Capital Markets LLC 8,308 5,114 3,194

Geographic Information and Busi

Geographic Information and Business Segments	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Geographic Information and Business Segments	Geographic Information and Business Segments The Company operates its business in the U.S. and internationally, primarily in Europe and Asia. Significant transactions and balances between geographic regions occur primarily as a result of certain Company’s subsidiaries incurring operating expenses such as employee compensation, communications and data processing and other overhead costs, for the purpose of providing execution, clearing and other support services to affiliates. Charges for transactions between regions are designed to approximate full costs. Intra-region income and expenses and related balances have been eliminated in the geographic information presented below to accurately reflect the external business conducted in each geographical region. The revenues are attributed to countries based on the locations of the subsidiaries. The following table presents total revenues by geographic area for the three and nine months ended September 30, 2018 and 2017 : Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Revenues: United States $ 245,631 $ 218,042 $ 1,266,047 $ 399,361 Ireland 21,938 17,874 60,563 79,129 United Kingdom 479 10,485 15,324 10,485 Singapore 26,921 22,601 95,757 72,210 Others 154 2,284 612 2,276 Total revenues $ 295,123 $ 271,286 $ 1,438,303 $ 563,461 Prior to the Acquisition of KCG, the Company was managed and operated as one business, and, accordingly, operated under one reportable segment. As a result of the acquisition of KCG, beginning in the third quarter of 2017 the Company has three operating segments: (i) Market Making; (ii) Execution Services; and (iii) Corporate. The Market Making segment principally consists of market making in the cash, futures and options markets across global equities, options, fixed income, currencies and commodities. As a market maker, the Company commits capital on a principal basis by offering to buy securities from, or sell securities to, broker dealers, banks and institutions. The Company engages in principal trading in the Market Making segment direct to clients as well as in a supplemental capacity on exchanges, ECNs and alternative trading systems ATSs. The Company is an active participant on all major global equity and futures exchanges and also trades on substantially all domestic electronic options exchanges. As a complement to electronic market making, the cash trading business handles specialized orders and also transacts on the OTC Bulletin Board marketplaces operated by the OTC Markets Group Inc. and the AIM. The Execution Services segment comprises agency-based trading and trading venues, offering execution services in global equities, options, futures and fixed income on behalf of institutions, banks and broker dealers as well as technology services revenues. The Company earns commissions and commission equivalents as an agent on behalf of clients as well as between principals to transactions; in addition, the Company will commit capital on behalf of clients as needed. Agency-based, execution-only trading in the segment is done primarily through a variety of access points including: (i) algorithmic trading and order routing in global equities and options; (ii) institutional sales traders executing program, block and riskless principal trades in global equities and ETFs; (iii) a fixed income ECN that also offers trading applications; and (iv) an ATS for U.S. equities. Technology licensing fees are earned from third parties for licensing of the Company’s proprietary risk management and trading infrastructure technology and the provision of associated management and hosting services. The Corporate segment contains the Company's investments, principally in strategic trading-related opportunities and maintains corporate overhead expenses and all other income and expenses that are not attributable to the Company's other segments. Management evaluates the performance of its segments on a pre-tax basis. Segment assets and liabilities are not used for evaluating segment performance or in deciding how to allocate resources to segments. The Company’s total revenues and income before income taxes and noncontrolling interest (“Pre-tax earnings”) by segment for the three months ended September 30, 2018 and 2017 are summarized in the following table: (in thousands) Market Making Execution Services Corporate (1) Consolidated Total 2018: Total revenue $ 264,370 $ 34,206 $ (3,453 ) $ 295,123 Income before income taxes and noncontrolling interest 39,744 129 (10,448 ) 29,425 2017: Total revenue 228,582 39,077 3,627 271,286 Income (loss) before income taxes and noncontrolling interest (19,322 ) (6,017 ) (21,156 ) (46,495 ) (1) Amounts shown in the Corporate segment include eliminations of income statement and balance sheet items included in the Company's other segments. The Company's Pre-tax earnings by segment for the nine months ended September 30, 2018 and 2017 are summarized in the following table: (in thousands) Market Making Execution Services Corporate (1) Consolidated Total 2018 Total revenue $ 984,601 $ 458,759 $ (5,057 ) $ 1,438,303 Income before income taxes and noncontrolling interest 262,910 331,703 (47,028 ) 547,585 2017 Total revenue 514,823 44,964 3,674 563,461 Income (loss) before income taxes and noncontrolling interest 17,241 (4,913 ) (29,749 ) (17,421 ) (1) Amounts shown in the Corporate segment include eliminations of income statement and balance sheet items included in the Company's other segments.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company incurs expenses and maintains balances with its affiliates in the ordinary course of business. As of September 30, 2018 , and December 31, 2017 the Company had a payable of $3.7 million and a receivable of $0.1 million to its affiliates, respectively. The Company conducts securities lending transactions with Industrial and Commercial Bank of China (“ICBC”), which is partially owned by Temasek and its affiliates. As of September 30, 2018 , the Company had a securities loaned contract of $0.4 million with ICBC. The Company had a securities borrowed contract of $23.1 million and a securities loaned contract of $1.1 million outstanding with ICBC as of December 31, 2017 . The Company purchases network connections services from affiliates of Level 3 Communications (“Level 3”). Temasek and its affiliates have a significant ownership interest in Level 3. The Company paid $0.4 million and $0.5 million for the three months ended September 30, 2018 and 2017 , respectively, and $1.9 million and $1.6 million for the nine months ended September 30, 2018 and 2017 , respectively, to Level 3 for these services. The Company purchases and leases computer equipment and maintenance and support from affiliates of Dell Inc. (“Dell”). Temasek and its affiliates have a significant ownership interest in Dell. The Company paid $0.5 million for the three months ended September 30, 2017 , and $0.8 million and $1.9 million for the nine months ended September 30, 2018 and 2017 , respectively, to Dell for these purchases and leases. The Company purchases market data and software licenses from affiliates of Markit Group Holdings Limited (“MarkIt”). Temasek and its affiliates have a significant ownership interest in MarkIt. For the three and nine months ended September 30, 2018 , the amounts paid to MarkIt for these services were immaterial and $0.4 million , respectively. The amount paid to MarkIt was immaterial for the three and nine months ended September 30, 2017 . The Company has held a minority interest in SBI since 2016 (See Note 11 "Financial Assets and Liabilities" ). The Company pays exchange fees to SBI for the trading activities conducted on its proprietary trading system. The Company paid $1.5 million and $1.4 million for the three months ended September 30, 2018 and 2017 , respectively, and $6.2 million and $4.1 million for the nine months ended September 30, 2018 and 2017 , respectively, to SBI for these trading activities. The Company makes payments to two JVs (See Note 2, “Summary of Significant Accounting Policies”) to fund the construction of the microwave communication networks, and to purchase microwave communication networks, which are recorded within communications and data processing on the condensed consolidated statements of comprehensive income. The Company made payments of $3.0 million and $0.2 million to the JVs for the three months ended September 30, 2018 and 2017 , respectively, and $13.1 million and $0.4 million for the nine months ended September 30, 2018 and 2017 , respectively.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated subsequent events for adjustment to or disclosure in its condensed consolidated financial statements through the date of this report, and has not identified any recordable or disclosable events, not otherwise reported in these condensed consolidated financial statements or the notes thereto, except for the following: On November 6, 2018, the Company’s board of directors declared a dividend of $0.24 per share of Class A common stock and Class B common stock and per Restricted Stock Unit that will be paid on December 14, 2018 to holders of record as of November 30, 2018. On November 6, 2018, the Company and Investment Technology Group, Inc. ("ITG") entered into a definitive agreement (the “ITG Merger Agreement”) whereby the Company will acquire ITG in a cash transaction valued at $30.30 per ITG share, or a total of approximately $1.0 billion (the “ITG Acquisition”). The ITG Acquisition is expected to close during the first half of 2019 after receipt of all required regulatory approvals and ITG shareholder approval. The Company intends to finance the ITG Acquisition solely with debt financing (collectively with the ITG Acquisition and related transactions, the “ITG Transactions”) and has entered into a debt commitment letter with Jefferies Finance LLC and Royal Bank of Canada for gross new borrowings of $1.5 billion , the proceeds of which will be used to pay the merger consideration and related fees and to refinance the Company’s existing first lien term loan.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The Company's condensed consolidated financial statements are prepared in conformity with U.S. GAAP, which require management to make estimates and assumptions regarding measurements including the fair value of trading assets and liabilities, goodwill and intangibles, compensation accruals, capitalized software, income tax, and other matters that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accordingly, actual results could differ materially from those estimates.
Earnings Per Share	Earnings Per Share Earnings per share (“EPS”) is calculated on both a basic and diluted basis. Basic EPS excludes dilution and is calculated by dividing income available to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted EPS is calculated by dividing the net income available for common stockholders by the diluted weighted average shares outstanding for that period. Diluted EPS includes the determinants of the basic EPS and, in addition, reflects the dilutive effect of shares of common stock estimated to be distributed in the future under the Company’s share based compensation plans. The Company grants restricted stock units (“RSUs”), which entitle recipients to receive nonforfeitable dividends during the vesting period on a basis equivalent to the dividends paid to holders of common stock. As a result, the unvested RSUs meet the definition of a participating security requiring the application of the two-class method. Under the two-class method, earnings available to common shareholders, including both distributed and undistributed earnings, are allocated to each class of common stock and participating securities according to dividends declared and participating rights in undistributed earnings, which may cause diluted EPS to be more dilutive than the calculation using the treasury stock method.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include money market accounts, which are payable on demand, and short-term investments with an original maturity of less than 90 days. The Company maintains cash in bank deposit accounts that, at times, may exceed federally insured limits. The Company manages this risk by selecting financial institutions deemed highly creditworthy to minimize the risk.
Securities Borrowed and Securities Loaned	Securities Borrowed and Securities Loaned The Company conducts securities borrowing and lending activities with external counterparties. In connection with these transactions, the Company receives or posts collateral, which comprises cash and/or securities. In accordance with substantially all of its stock borrow agreements, the Company is permitted to sell or repledge the securities received. Securities borrowed or loaned are recorded based on the amount of cash collateral advanced or received. The initial cash collateral advanced or received generally approximates or is greater than 102% of the fair value of the underlying securities borrowed or loaned. The Company monitors the fair value of securities borrowed and loaned, and delivers or obtains additional collateral as appropriate. Receivables and payables with the same counterparty are not offset in the condensed consolidated statements of financial condition. Interest received or paid by the Company for these transactions is recorded gross on an accrual basis under interest and dividends income or interest and dividends expense in the condensed consolidated statements of comprehensive income.
Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase	Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase In a repurchase agreement, securities sold under agreements to repurchase are treated as collateralized financing transactions and are recorded at contract value, plus accrued interest, which approximates fair value. It is the Company's policy that its custodian take possession of the underlying collateral securities with a fair value approximately equal to the principal amount of the repurchase transaction, including accrued interest. For reverse repurchase agreements, the Company typically requires delivery of collateral with a fair value approximately equal to the carrying value of the relevant assets in the condensed consolidated statements of financial condition. To ensure that the fair value of the underlying collateral remains sufficient, the collateral is valued daily with additional collateral obtained or excess collateral returned, as permitted under contractual provisions. The Company does not net securities purchased under agreements to resell transactions with securities sold under agreements to repurchase transactions entered into with the same counterparty. The Company has entered into bilateral and tri-party term and overnight repurchase and other collateralized financing agreements which bear interest at negotiated rates. The Company receives cash and makes delivery of financial instruments to a custodian who monitors the market value of these instruments on a daily basis. The market value of the instruments delivered must be equal to or in excess of the principal amount loaned under the repurchase agreements plus the agreed upon margin requirement. The custodian may request additional collateral, if appropriate. Interest received or paid by the Company for these transactions is recorded gross on an accrual basis under interest and dividends income or interest and dividends expense in the condensed consolidated statements of comprehensive income.
Receivables from/Payables to Broker-dealers and Clearing Organizations	Receivables from/Payables to Broker-dealers and Clearing Organizations As of September 30, 2018 and December 31, 2017 , receivables from and payables to broker-dealers and clearing organizations primarily represented amounts due for unsettled trades, open equity in futures transactions, securities failed to deliver or failed to receive, deposits with clearing organizations or exchanges and balances due from or due to prime brokers in relation to the Company’s trading. Amounts receivable from broker-dealers and clearing organizations may be restricted to the extent that they serve as deposits for securities sold, not yet purchased. The Company presents its balances, including outstanding principal balances on all credit facilities, on a net by counterparty basis within receivables from and payables to broker-dealers and clearing organizations when the criteria for offsetting are met. In the normal course of business, a significant portion of the Company’s securities transactions, money balances, and security positions are transacted with several third-party brokers. The Company is subject to credit risk to the extent any broker with whom it conducts business is unable to fulfill contractual obligations on its behalf. The Company monitors the financial condition of such brokers and to minimize the risk of any losses from these counterparties.
Financial Instruments Owned Including Those Pledged as Collateral and Financial Instruments Sold, Not Yet Purchased	Financial Instruments Owned Including Those Pledged as Collateral and Financial Instruments Sold, Not Yet Purchased Financial instruments owned and Financial instruments sold, not yet purchased relate to market making and trading activities, and include listed and other equity securities, listed equity options and fixed income securities. The Company records financial instruments owned, including those pledged as collateral, and financial instruments sold, not yet purchased at fair value. Gains and losses arising from financial instrument transactions are recorded net on a trade-date basis in trading income, net, in the condensed consolidated statements of comprehensive income.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or would be paid to transfer a liability (i.e., the exit price) in an orderly transaction between market participants at the measurement date. Fair value measurements are not adjusted for transaction costs. The recognition of “block discounts” for large holdings of unrestricted financial instruments where quoted prices are readily and regularly available in an active market is prohibited. The Company categorizes its financial instruments into a three level hierarchy which prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy level assigned to each financial instrument is based on the assessment of the transparency and reliability of the inputs used in the valuation of such financial instruments at the measurement date based on the lowest level of input that is significant to the fair value measurement. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurement) and the lowest priority to unobservable inputs (level 3 measurements). Financial instruments measured and reported at fair value are classified and disclosed in one of the following categories based on inputs: Level 1 — Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 — Quoted prices in markets that are not active and financial instruments for which all significant inputs are observable, either directly or indirectly; or Level 3 — Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. Transfers in or out of levels are recognized based on the beginning fair value of the period in which they occurred.
Fair Value Option	Fair Value Option The fair value option election allows entities to make an irrevocable election of fair value as the initial and subsequent measurement attribute for certain eligible financial assets and liabilities. Unrealized gains and losses on items for which the fair value option has been elected are recorded in other, net in the condensed consolidated statements of comprehensive income. The decision to elect the fair value option is determined on an instrument by instrument basis, which must be applied to an entire instrument and is irrevocable once elected.
Derivative Instruments	Derivative Instruments Derivative instruments are used for trading purposes, including economic hedges of trading instruments, are carried at fair value, and include futures, forward contracts, and options. Gains or losses on these derivative instruments are recognized currently within trading income, net in the condensed consolidated statement of comprehensive income. Fair values for exchange-traded derivatives, principally futures, are based on quoted market prices. Fair values for over-the-counter derivative instruments, principally forward contracts, are based on the values of the underlying financial instruments within the contract. The underlying instruments are currencies, which are actively traded. The Company presents its derivatives balances on a net-by-counterparty basis when the criteria for offsetting are met. Cash flows associated with such derivative activities are included in cash flows from operating activities on the condensed consolidated statements of cash flows
Property, Equipment and Occupancy	Property, Equipment and Occupancy Property and equipment are carried at cost, less accumulated depreciation, except for the assets acquired in connection with acquisitions using the purchase accounting method, which were recorded at fair value on the respective date of acquisitions. Depreciation is provided using the straight-line method over estimated useful lives of the underlying assets. Routine maintenance, repairs and replacement costs are expensed as incurred and improvements that appreciably extend the useful life of the assets are capitalized. When property and equipment are sold or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in income. Property and equipment are reviewed for impairment whenever events or changes in circumstances indicate that the related carrying amount may not be recoverable. Furniture, fixtures, and equipment are depreciated over three to seven years. Leasehold improvements are amortized over the lesser of the life of the improvement or the term of the lease. The Company recognizes rent expense under operating leases with fixed rent escalations, lease incentives and free rent periods on a straight-line basis over the lease term beginning on the date the Company takes possession of or controls the use of the space, including during free rent periods.
Lease Loss Accrual	Lease Loss Accrual The Company’s policy is to identify excess real estate capacity and where applicable, accrue for related future costs, net of projected sub-lease income upon the date the Company ceases to use the excess real estate, which is recorded under operating and administrative in the condensed consolidated statements of comprehensive income. Such accrual is adjusted to the extent the actual terms of sub-leased property differ from the previous assumptions used in the calculation of the accrual.
Capitalized Software	Capitalized Software The Company capitalizes costs of materials, consultants, and payroll and payroll related costs for employees incurred in developing internal-use software. Costs incurred during the preliminary project and post-implementation stages are charged to expense. Management’s judgment is required in determining the point at which various projects enter the stages at which costs may be capitalized, in assessing the ongoing value of the capitalized costs, and in determining the estimated useful lives over which the costs are amortized. Capitalized software development costs and related accumulated amortization are included in property, equipment and capitalized software in the accompanying condensed consolidated statements of financial condition and are amortized over a period of 1.5 to 2.5 years , which represents the estimated useful lives of the underlying software.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the underlying net tangible and intangible assets of the Company’s acquisitions. Goodwill is not amortized but is tested for impairment on an annual basis and between annual tests whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Goodwill is tested at the reporting unit level, which is defined as an operating segment or one level below the operating segment. The Company tests goodwill for impairment on an annual basis on July 1 and on an interim basis when certain events or circumstances exist. In the impairment test as of July 1, 2018, the Company assessed qualitative factors as described in ASC 350-20 for each of its reporting units for any indicators that the fair values of the reporting units were less than their carrying values.
Intangible Assets	Intangible Assets The Company amortizes finite-lived intangible assets over their estimated useful lives. Finite-lived intangible assets are tested for impairment when impairment indicators are present, and if impaired, they are written down to fair value.
Exchange Memberships and Stock	Exchange Memberships and Stock Exchange memberships are recorded at cost or, if any other than temporary impairment in value has occurred, at a value that reflects management’s estimate of fair value. Exchange memberships acquired in connection with the Acquisition were recorded at their fair value on the date of acquisition. Exchange stock includes shares that entitle the Company to certain trading privileges. The Company’s exchange memberships and stock are included in intangibles in the condensed consolidated statements of financial condition.
Trading Income, net	Trading Income, net Trading income, net is comprised of changes in the fair value of trading assets and liabilities (i.e., unrealized gains and losses) and realized gains and losses on trading assets and liabilities. Trading gains and losses on financial instruments owned and financial instruments sold, not yet purchased are recorded on the trade date and reported on a net basis in the condensed consolidated statements of comprehensive income.
Commissions, net and Technology Services	Commissions, net and Technology Services Commissions, net, which primarily comprise commissions and commission equivalents earned on institutional client orders, are recorded on a trade date basis. Under a commission management program, the Company allows institutional clients to allocate a portion of their gross commissions to pay for research and other services provided by third parties. The Company recognizes the related revenue when the third party research services are rendered and payments are made. As the Company acts as an agent in these transactions, it records such expenses on a net basis within commissions and technology services in the condensed consolidated statements of comprehensive income. Technology services revenues consist of technology licensing fees and agency commission fees. Technology licensing fees are earned from third parties for licensing of the Company’s proprietary risk management and trading infrastructure technology and the provision of associated management and hosting services. These fees include both upfront and annual recurring fees, as well as, in certain cases, contingent fees based on client revenues, which represent variable consideration. The services offered under these contracts have the same pattern of transfer; accordingly, they are being measured and recognized as a single performance obligation. The performance obligation is satisfied over time, and accordingly, revenue is recognized as time passes. Variable consideration has not been included in the transaction price as the amount of consideration is contingent on factors outside the Company’s control and thus it is not probable that a significant reversal of cumulative revenue recognized will not occur. Recurring fees, which exclude variable consideration, are billed and collected on a quarterly basis.
Interest and Dividends Income/Interest and Dividends Expense	Interest and Dividends Income/Interest and Dividends Expense Interest income and interest expense are accrued in accordance with contractual rates. Interest income consists of interest earned on collateralized financing arrangements and on cash held by brokers. Interest expense includes interest expense from collateralized transactions, margin and related lines of credit. Dividends on financial instruments owned including those pledged as collateral and financial instruments sold, not yet purchased are recorded on the ex-dividend date and interest is recognized on an accrual basis.
Brokerage, Exchange and Clearance Fees, Net	Brokerage, Exchange and Clearance Fees, Net Brokerage, exchange and clearance fees, net, comprise the costs of executing and clearing trades and are recorded on a trade date basis. Rebates consist of volume discounts, credits or payments received from exchanges or other market places related to the placement and/or removal of liquidity from the order flow in the marketplace. Rebates are recorded on an accrual basis and included net within brokerage, exchange and clearance fees in the accompanying condensed consolidated statements of comprehensive income.
Payments for Order Flow	Payments for Order Flow Payments for order flow represent payments to broker-dealer clients, in the normal course of business, for directing their order flow in U.S. equities to the Company. Payments for order flow are recorded on a trade-date basis in the condensed consolidated statements of comprehensive income.
Income Taxes	Income Taxes Subsequent to consummation of the Reorganization Transactions and the IPO, the Company is subject to U.S. federal, state and local income taxes on its taxable income. The Company's subsidiaries are subject to income taxes in the respective jurisdictions (including foreign jurisdictions) in which they operate. Prior to the consummation of the Reorganization Transactions and the IPO, no provision for United States federal, state and local income tax was required, as Virtu Financial is a limited liability company and is treated as a pass-through entity for United States federal, state, and local income tax purposes. The provision for income tax is comprised of current tax and deferred tax. Current tax represents the tax on current year tax returns, using tax rates enacted at the balance sheet date. The deferred tax assets are recognized in full and then reduced by a valuation allowance if it is more likely than not that some or all of the deferred tax assets will not be recognized. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the applicable taxing authority, including resolution of the appeals or litigation processes, based on the technical merits of the position. The tax benefits recognized in the condensed consolidated financial statements from such a position are measured based on the largest benefit for each such position that has a greater than fifty percent likelihood of being realized upon ultimate resolution. Many factors are considered when evaluating and estimating the tax positions and tax benefits. Such estimates involve interpretations of regulations, rulings, case law, etc. and are inherently complex. The Company’s estimates may require periodic adjustments and may not accurately anticipate actual outcomes as resolution of income tax treatments in individual jurisdictions typically would not be known for several years after completion of any fiscal year.
Comprehensive Income and Foreign Currency Translation	Comprehensive Income and Foreign Currency Translation Comprehensive income consists of two components: net income and other comprehensive income (“OCI”). The Company’s OCI is comprised of foreign currency translation adjustments. Assets and liabilities of operations having non-U.S. dollar functional currencies are translated at period-end exchange rates, and revenues and expenses are translated at weighted average exchange rates for the period. Gains and losses resulting from translating foreign currency financial statements, net of related tax effects, are reflected in accumulated other comprehensive income, a separate component of stockholders’ equity. The Company's foreign subsidiaries generally use the U.S. dollar as their functional currency. The Company also has subsidiaries that utilize a functional currency other than the U.S. dollar, primarily comprising its subsidiaries domiciled in Ireland, which utilizes the Euro as the functional currency. The Company may seek to reduce the impact of fluctuations in foreign exchange rates on its net investment in certain non-U.S. operations through the use of foreign currency forward contracts. For foreign currency forward contracts designated as hedges, the Company assesses its risk management objectives and strategy, including identification of the hedging instrument, the hedged item and the risk exposure and how effectiveness is to be assessed prospectively and retrospectively. The effectiveness of the hedge is assessed based on the overall changes in the fair value of the forward contracts. For qualifying net investment hedges, any gains or losses, to the extent effective, are included in Accumulated other comprehensive income on the condensed consolidated statements of financial condition and Cumulative translation adjustment, net of tax, on the condensed consolidated statements of comprehensive income. The ineffective portion, if any, is recorded in investment income and other, net on the condensed consolidated statements of operations.
Share-Based Compensation	Share-Based Compensation The fair value of awards issued for compensation prior to the Reorganization Transactions and the IPO was determined by management, with the assistance of an independent third party valuation firm, using a projected annual forfeiture rate, where applicable, on the date of grant. Share-based awards issued for compensation in connection with or subsequent to the Reorganization Transactions and the IPO pursuant to the VFI 2015 Management Incentive Plan (as amended, the “2015 Amended and Restated Management Incentive Plan”) were in the form of stock options, Class A common stock and RSUs. The fair value of the stock option grants is determined through the application of the Black-Scholes-Merton model. The fair value of the Class A common stock and RSUs are determined based on the volume weighted average price for the three days preceding the grant, and with respect to the RSUs, a projected annual forfeiture rate. The fair value of share-based awards granted to employees is expensed based on the vesting conditions and are recognized on a straight line basis over the vesting period. The Company records as treasury stock shares repurchased from its employees for the purpose of settling tax liabilities incurred upon the issuance of Class A common stock, the vesting of RSUs or the exercise of stock options.
Variable Interest Entities	Variable Interest Entities A variable interest entity (“VIE”) is an entity that lacks one or more of the following characteristics (i) the total equity investment at risk is sufficient to enable the entity to finance its activities independently and (ii) the equity holders have the power to direct the activities of the entity that most significantly impact its economic performance, the obligation to absorb the losses of the entity and the right to receive the residual returns of the entity. The Company will be considered to have a controlling financial interest and will consolidate a VIE if it has both (i) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. In October 2016, the Company invested in a joint venture (“JV”) with nine other parties. One of the parties was KCG. Upon the Merger, KCG was required to relinquish their ownership in the JV. As of September 30, 2018 , each of the remaining parties owns approximately 11% of the voting shares and 11% of the equity of this JV. In addition, as a result of the Acquisition of KCG, the Company owns 50% of the voting shares and 50% of the equity of another JV. These two JVs build and maintain microwave communication networks in the U.S., Europe, and Asia. The Company and its JV partners each pay monthly fees for the use of the microwave communication networks in connection with their respective trading activities, and the JVs may sell excess bandwidth that is not utilized by the JV members to third parties. The JVs meet the criteria to be considered VIEs. In each of the JVs, the Company does not have the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance; therefore it does not have a controlling financial interest in and does not consolidate the JVs. The Company records its interest in each JV under the equity method of accounting and records its investment in the JVs within Other assets and its amounts payable for communication services provided by the JV within Accrued expenses and other liabilities on the condensed consolidated statements of financial condition. The Company records its pro-rata share of each JV's earnings or losses within Other, net and fees related to the use of communication services provided by the JVs within Communications and data processing on the condensed consolidated statements of comprehensive income.
Accounting Pronouncements, Recently Adopted and Accounting Pronouncements, Not Yet Adopted	Accounting Pronouncements, Recently Adopted Revenue Recognition - In May 2014, the FASB issued Accounting Standard Update (“ASU”) 2014-9, Revenue from Contracts with Customers . ASU 2014-9 is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. ASU 2014-9 also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. The Company adopted the new revenue standard on January 1, 2018 by applying the modified retrospective method, which did not result in a transition adjustment. The new standard does not apply to revenue associated with financial instruments that are accounted for under other U.S. GAAP, and as a result, did not have a material impact on the Company’s condensed consolidated financial statements, which are most closely associated with financial instruments, including trading income, net, and interest and dividends income. The new revenue standard primarily impacts revenues from technology services, commissions and soft-dollar arrangements generated by execution services. The additional disclosures required by the new standard have been included in Note 13 "Revenues from Contracts with Customers" . Financial Assets and Liabilities — In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The ASU affects the accounting for equity investments, financial liabilities under fair value option and presentation and disclosure requirements of financial instruments. The ASU affects all entities that hold financial assets or owe financial liabilities and is effective for annual reporting periods (including interim periods) beginning after December 15, 2017. The Company does not currently classify any equity securities as available for sale, and it does not apply the fair value option to its own debt issuances. The Company has adopted this ASU as of January 1, 2018, and it did not have a material impact on its condensed consolidated financial statements. Income Taxes – In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 749): Intra-Entity Transfers of Assets Other Than Inventory . The ASU requires the reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of the transactions are eliminated in consolidation. Any deferred tax asset that arises in the buyer’s jurisdiction would also be recognized at the time of the transfer. The ASU is effective for reporting periods beginning after December 15, 2017. The Company adopted this ASU on January 1, 2018, and it did not have a material impact on its condensed consolidated financial statements. Business Combinations - In January 2017, the FASB issued ASU 2017-1, Business Combinations (Topic 805), Clarifying the Definition of a Business , to amend the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The ASU is effective for reporting periods beginning after December 15, 2017. The Company adopted this ASU on January 1, 2018, and it did not have a material impact on its condensed consolidated financial statements. Accounting Pronouncements, Not Yet Adopted as of September 30, 2018 Leases — In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . Under the new ASU, a lessee will be required to recognize assets and liabilities for leases with lease terms of more than 12 months. The liability will be equal to the present value of the future lease payments. The asset, referred to as a “right-of-use asset” will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, leases will be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting, but without explicit bright lines. The Company's implementation effort is ongoing, and it will adopt this ASU on January 1, 2019. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases , which modifies certain aspects of ASC Topic 842, including allowing entities to adopt the new leasing standard as of January 1, 2019, without restating prior periods presented, and providing certain practical expedients including allowing lessors not to separate out lease and non-lease components when certain conditions are met. The Company is not anticipating recognizing lease assets and lease liabilities for leases with a determined lease term of twelve months or less and which are not expected to be renewed. Upon adoption of this ASU, the Company expects to report grossed up assets and liabilities on its condensed consolidated statement of financial condition as a result of recognizing right-of-use assets and lease liabilities related to its operating leases, which currently are not reflected in its condensed consolidated statement of financial condition. Goodwill - In January, 2017, the FASB issued ASU 2017-4, Intangibles—Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment . To simplify the subsequent measurement of goodwill, this ASU eliminated Step 2 from the goodwill impairment test. In computing the implied fair value of goodwill under Step 2, an entity had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities (including unrecognized assets and liabilities) following the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. Instead, under this ASU, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. This ASU also eliminated the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. This ASU is effective for public entities in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company does not expect the adoption of this ASU to have a material impact on its condensed consolidated financial statements. Stock Compensation - In June 2018, the FASB issued ASU 2018-07, Compensation, Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting , with the objective of conforming the accounting for share-based awards to non-employees to the accounting for awards granted to employees. Previously, non-employee awards were measured at the vesting date, rather than the grant date, which effectively required the awards to be marked to market until the award vested. Under the new ASU, companies will be required to measure non-employee awards at the fair value of the instruments issued at the grant date. Entities will also be able to consider the probability of the recipient satisfying any performance conditions. The ASU is effective for periods beginning after December 15, 2018, including interim periods within that fiscal year. The Company is currently evaluating the impact of this standard on its condensed consolidated financial statements. The Company does not currently make share-based awards to non-employees, and does not expect the adoption of this ASU to have a material impact on its condensed consolidated financial statements. Fair Value Measurement - In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement , which modified the disclosure requirements on fair value measurements in ASC Topic 820, Fair Value Measurement. Disclosure requirements were eliminated for the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, the policy for timing of transfers between levels, and the valuation processes for Level 3 fair value measurements. Disclosure requirements were modified for liquidation of investments in certain entities that calculate net asset value, and for measurement uncertainty disclosures. Disclosure requirements were added for changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. The ASU is effective for periods beginning after December 15, 2019, including interim periods within that fiscal year. The Company does not expect the adoption of this ASU to have a material impact on its condensed consolidated financial statements.
Revenue Recognition	Revenue Recognition The Company adopted ASC Topic 606, Revenue from Contracts with Customers as of January 1, 2018 in the condensed consolidated financial statements by applying the modified retrospective method. The Company’s revenue recognition methods for its contracts with customers prior to the adoption of Topic 606 are consistent with its methods after the adoption of Topic 606. Accordingly, the adoption of the new standard did not result in a transition adjustment to opening retained earnings, and as a result, revenues for contracts with customers would not have been adjusted in prior periods and are not presented herein on an adjusted basis. The new revenue guidance does not apply to revenue associated with financial instruments, including loans and securities that are accounted for under other U.S. GAAP, and as a result, did not have an impact on the elements of the Company’s condensed consolidated statement of comprehensive income most closely associated with financial instruments, including trading income, net and interest and dividend income. The new standard primarily impacts the presentation of the following revenue streams: • Commissions, net. The Company earns commission revenue by acting as an agent on behalf of customers. The Company’s performance obligations consist of trade execution and clearing services and are satisfied on the trade date; accordingly, commission revenues are recorded on the trade date. Commission revenues are paid on settlement date; therefore, a receivable is recognized as of the trade date. Under a commission management program, the Company allows institutional clients to allocate a portion of their gross commissions to pay for research and other services provided by third parties. As the Company acts as an agent in these transactions, it records such expenses on a net basis within Commissions and technology services in the condensed consolidated statements of comprehensive income. • Technology services. The Company’s technology services revenues consist of technology licensing fees and agency commission fees. Technology licensing fees are earned from third parties for licensing of the Company’s proprietary risk management and trading infrastructure technology and the provision of associated management and hosting services. These fees include both upfront and annual recurring fees as well as, in certain cases, contingent fees based on customer revenues, which represent variable consideration. The services offered under these contracts are delivered as an integrated package and are interdependent and have the same pattern of transfer to the customer; accordingly, the Company measures and recognizes them as a single performance obligation. The performance obligation is satisfied over time, and, therefore, revenue is recognized as time passes. Variable consideration has not been included in the transaction price as the amount of consideration is contingent on factors outside the Company’s control and thus it is not probable that a significant reversal of cumulative revenue recognized will not occur. Recurring fees, which exclude variable consideration, are billed and collected on a quarterly basis and are included within Receivables from broker dealers and clearing organizations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of nonconsolidated VIE	The following table presents the Company’s nonconsolidated VIEs at September 30, 2018 : Carrying Amount Maximum Exposure to Loss VIEs' assets (in thousands) Asset Liability Equity investment $ 18,669 $ — $ 18,669 $ 48,557 The following table presents the Company’s nonconsolidated VIEs at December 31, 2017 : Carrying Amount Maximum Exposure to Loss VIEs' assets (in thousands) Asset Liability Equity investment $ 18,799 $ — $ 18,799 $ 41,936

Acquisition of KCG Holdings, _2

Acquisition of KCG Holdings, Inc. (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of preliminary allocation of intangible assets, amortization period and goodwill	Amounts allocated to intangible assets, the amortization period and goodwill were as follows: (in thousands) Amount Amortization Years Technology $ 67,700 1-6 years Customer relationships 94,000 13 - 17 years Trade names 1,000 10 years Favorable leases 5,895 2-15 years Exchange memberships 6,400 Indefinite Intangible assets $ 174,995 Goodwill 128,286 Total $ 303,281

Sale of BondPoint (Tables)

Sale of BondPoint (Tables)	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Summary of assets and liabilities of businesses held for sale	A summary of the carrying value of BondPoint and gain on sale of BondPoint is as follows: (in thousands) Total sale proceeds received $ 400,192 Business assets and liabilities held for sale as of December 31, 2017: Receivables from broker dealers and clearing organizations 3,383 Intangibles and other assets 51,687 Liabilities (728 ) Total carrying value of BondPoint as of December 31, 2017: 54,342 Goodwill adjustment allocated to BondPoint 8,300 Gain on sale of BondPoint 337,550 Transaction costs 8,568 Gain on sale of BondPoint, net of transaction costs $ 328,982

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of reconciliation of net income before noncontrolling interest to net income available for common stockholders	The below table contains a reconciliation of net income before noncontrolling interest to net income available for common stockholders: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Income (loss) before income taxes and noncontrolling interest $ 29,425 $ (46,495 ) $ 547,585 $ (17,421 ) Provision for (benefit from) income taxes 13,815 (6,505 ) 75,330 (2,918 ) Net income 15,610 (39,990 ) 472,255 (14,503 ) Noncontrolling interest (6,998 ) 26,472 (263,682 ) 6,466 Net income (loss) available for common stockholders $ 8,612 $ (13,518 ) $ 208,573 $ (8,037 )
Schedule of basic earnings per share	The calculation of basic and diluted earnings per share is presented below: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except for share or per share data) 2018 2017 2018 2017 Basic earnings per share: Net income (loss) available for common stockholders $ 8,612 $ (13,518 ) $ 208,573 $ (8,037 ) Less: Dividends and undistributed earnings allocated to participating securities (418 ) (314 ) (4,029 ) (997 ) Net income (loss) available for common stockholders, net of dividends and undistributed earnings allocated to participating securities 8,194 (13,832 ) 204,544 (9,034 ) Weighted average shares of common stock outstanding: Class A 106,692,034 79,199,142 99,038,084 53,520,346 Basic earnings per share $ 0.08 $ (0.17 ) $ 2.07 $ (0.17 )
Schedule of diluted earnings per share	Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except for share or per share data) 2018 2017 2018 2017 Diluted earnings per share: Net income (loss) available for common stockholders, net of dividends and undistributed earnings allocated to participating securities $ 8,194 $ (13,832 ) $ 204,544 $ (9,034 ) Weighted average shares of common stock outstanding: Class A Issued and outstanding 106,692,034 79,199,142 99,038,084 53,520,346 Issuable pursuant to 2015 Management Incentive Plan (1) 436,172 — 1,430,776 — 107,128,206 79,199,142 100,468,860 53,520,346 Diluted earnings per share $ 0.08 $ (0.17 ) $ 2.04 $ (0.17 ) (1) The dilutive impact of unexercised stock options excludes from the computation of EPS 1,578,617 and 1,704,307 options for the three and nine months ended September 30, 2017 , respectively, because inclusion of the options would have been anti-dilutive.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill by segment	The following table presents the details of goodwill by segment: (in thousands) Market Making Execution Services Corporate Total Balance as of December 31, 2017 $ 755,292 $ 89,591 $ — $ 844,883 Goodwill adjustment allocated to BondPoint — (8,300 ) — (8,300 ) Balance as of September 30, 2018 $ 755,292 $ 81,291 $ — $ 836,583
Schedule of acquired intangible assets	Acquired intangible assets consisted of the following as of September 30, 2018 and December 31, 2017 : As of September 30, 2018 (in thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Useful Lives (Years) Purchased technology $ 110,000 $ 110,000 $ — 1.4 to 2.5 ETF issuer relationships 950 638 312 9 ETF buyer relationships 950 639 311 9 Technology 60,000 25,382 34,618 1 to 6 Customer relationships 49,000 4,885 44,115 12 Favorable occupancy leases 5,895 1,020 4,875 3 to 15 Exchange memberships 5,838 — 5,838 Indefinite $ 232,633 $ 142,564 $ 90,069 As of December 31, 2017 (in thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Useful Lives Purchased technology $ 110,000 $ 110,000 $ — 1.4 to 2.5 ETF issuer relationships 950 559 391 9 ETF buyer relationships 950 559 390 9 Leases 1,800 397 1,403 3 FCC licenses 200 19 181 7 Technology 60,000 9,644 50,356 1 to 6 Customer relationships 49,000 1,822 47,178 12 Favorable occupancy leases 5,895 408 5,487 3 to 15 Exchange memberships 5,838 — 5,838 Indefinite $ 234,633 $ 123,408 $ 111,224

Receivables from_Payables to _2

Receivables from/Payables to Broker-Dealers and Clearing Organizations (Tables)	9 Months Ended
	Sep. 30, 2018
Due to and from Broker-Dealers and Clearing Organizations [Abstract]
Summary of receivables from and payables to brokers-dealers and clearing organizations	The following is a summary of receivables from and payables to brokers-dealers and clearing organizations at September 30, 2018 and December 31, 2017 : (in thousands) September 30, 2018 December 31, 2017 Assets Due from prime brokers $ 370,599 $ 219,573 Deposits with clearing organizations 95,817 112,847 Net equity with futures commission merchants 260,705 203,711 Unsettled trades with clearing organization 150,265 173,778 Securities failed to deliver 229,944 248,088 Commissions and fees 8,434 14,021 Total receivables from broker-dealers and clearing organizations $ 1,115,764 $ 972,018 Liabilities Due to prime brokers $ 398,181 $ 197,439 Net equity with futures commission merchants 53,986 44,526 Unsettled trades with clearing organization 470,665 420,029 Securities failed to receive 28,077 51,143 Commissions and fees 1,434 3,068 Total payables to broker-dealers and clearing organizations $ 952,343 $ 716,205

Collateralized Transactions (Ta

Collateralized Transactions (Tables)	9 Months Ended
	Sep. 30, 2018
Collateralized Agreements [Abstract]
Summary of the fair value of collateralized transactions	The fair value of the collateralized transactions at September 30, 2018 and December 31, 2017 are summarized as follows: (in thousands) September 30, 2018 December 31, 2017 Securities received as collateral: Securities borrowed $ 1,261,472 $ 1,415,793 Securities purchased under agreements to resell 10,014 — $ 1,271,486 $ 1,415,793
Schedule of financial instruments owned and pledged, where counterparty has right to repledge	Financial instruments owned and pledged, where the counterparty has the right to repledge, at September 30, 2018 and December 31, 2017 consisted of the following: (in thousands) September 30, 2018 December 31, 2017 Equities $ 542,088 $ 586,251 U.S. and Non-U.S. government obligations — 99 Exchange traded notes 10,541 8,693 $ 552,629 $ 595,043

Borrowings (Tables)

Borrowings (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Instrument [Line Items]
Outstanding borrowings and financing capacity or unused available capacity under the Company’s borrowing arrangements	The following summarizes the Company’s broker-dealer credit facilities' carrying values, net of unamortized debt issuance costs, where applicable: At September 30, 2018 (in thousands) Interest Rate Financing Available Borrowing Outstanding Deferred Debt Issuance Cost Outstanding Borrowings, net Broker-dealer credit facilities: Uncommitted facility 3.17% $ 200,000 $ 10,000 $ (1,081 ) $ 8,919 Revolving credit facility 3.51% 500,000 7,000 (1,352 ) 5,648 $ 700,000 $ 17,000 $ (2,433 ) $ 14,567 At December 31, 2017 (in thousands) Interest Rate Financing Available Borrowing Outstanding Deferred Debt Issuance Cost Outstanding Borrowings, net Broker-dealer credit facilities: Uncommitted facility 2.42% $ 150,000 $ 25,000 $ — $ 25,000 Revolving credit facility 2.81% 500,000 7,000 (4,117 ) 2,883 $ 650,000 $ 32,000 $ (4,117 ) $ 27,883
Schedule of interest expense on debt	The following summarizes interest expense for the broker-dealer facilities. Interest expense is included within interest and dividends expense in the accompanying condensed consolidated statements of comprehensive income. Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Broker-dealer credit facilities: Uncommitted facility $ 428 $ 405 $ 1,458 $ 1,335 Committed facility (1) — 2 — 33 Revolving credit facility 60 — 212 — $ 488 $ 407 $ 1,670 $ 1,368 (1) Facility was terminated in July 2017.
Schedule of aggregate future required principal payments based on terms of loan	Aggregate future required minimum principal payments based on the terms of the long-term borrowings were as follows: (in thousands) September 30, 2018 2018 $ — 2019 — 2020 30,783 2021 and thereafter 900,000 Total principal of long-term borrowings $ 930,783
Short-Term Credit Facilities
Debt Instrument [Line Items]
Schedule of reconciliation of the senior secured credit facility	At September 30, 2018 Weighted Average Financing Borrowing Short-Term Credit Facilities: Short-term credit facilities (2) 4.27% $ 566,000 $ 144,660 $ 566,000 $ 144,660 At December 31, 2017 Weighted Average Interest Rate Financing Available Borrowing Outstanding Short-Term Credit Facilities: Short-term credit facilities (2) 3.86% $ 543,000 $ 205,677 $ 543,000 $ 205,677 (2) Outstanding borrowings were included with receivable from/ payable to broker-dealers and clearing organization within the condensed consolidated statements of financial condition.
Senior Secured Credit Facility
Debt Instrument [Line Items]
Schedule of reconciliation of the senior secured credit facility	The following summarizes the Company’s long-term borrowings, net of unamortized discount and debt issuance costs, where applicable: At September 30, 2018 (in thousands) Maturity Interest Outstanding Principal Discount Deferred Debt Issuance Cost Outstanding Borrowings, net Long-term borrowings: Fourth Amended and Restate Credit Agreement December 2021 5.09% $ 400,000 $ (360 ) $ (7,267 ) $ 392,373 Senior secured Second Lien Notes June 2022 6.75% 500,000 — (19,099 ) 480,901 SBI bonds January 2020 5.00% 30,783 — (30 ) 30,753 $ 930,783 $ (360 ) $ (26,396 ) $ 904,027 At December 31, 2017 (in thousands) Maturity Date Interest Rate Outstanding Principal Discount Deferred Debt Issuance Cost Outstanding Borrowings, net Long-term borrowings: Fourth Amended and Restate Credit Agreement December 2021 5.13% $ 900,000 $ (999 ) $ (18,504 ) $ 880,497 Senior secured Second Lien Notes June 2022 6.75% 500,000 — (22,961 ) 477,039 SBI bonds January 2020 5.00% 31,059 — (47 ) 31,012 $ 1,431,059 $ (999 ) $ (41,512 ) $ 1,388,548

Financial Assets and Liabilit_2

Financial Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Summary of fair value measurements measured on a recurring basis	The table below summarizes financial assets and liabilities not carried at fair value on a recurring basis as of September 30, 2018 : September 30, 2018 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Carrying Value Fair Value (Level 1) (Level 2) (Level 3) Assets Cash and cash equivalents $ 415,933 $ 415,933 $ 415,933 $ — $ — Securities borrowed 1,305,789 1,305,789 — 1,305,789 — Securities purchased under agreements to resell 10,014 10,014 — 10,014 — Receivables from broker dealers and clearing organizations 1,115,764 1,115,764 225,274 890,490 — Total Assets $ 2,847,500 $ 2,847,500 $ 641,207 $ 2,206,293 $ — Liabilities Short-term borrowings $ 14,567 $ 14,567 $ — $ 14,567 $ — Long-term borrowings 904,027 950,685 — 950,685 — Securities loaned 800,145 800,145 — 800,145 — Securities sold under agreements to repurchase 301,238 301,238 — 301,238 — Payables to broker dealer and clearing organizations 952,343 952,343 277,486 674,859 — Total Liabilities $ 2,972,320 $ 3,018,978 $ 277,486 $ 2,741,494 $ — The table below summarizes financial assets and liabilities not carried at fair value on a recurring basis as of December 31, 2017 : December 31, 2017 Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Carrying Value Fair Value (Level 1) (Level 2) (Level 3) Assets Cash and cash equivalents $ 532,887 $ 532,887 $ 532,887 $ — $ — Securities borrowed 1,471,172 1,471,172 — 1,471,172 — Receivables from broker dealers and clearing organizations 972,018 972,018 36,513 935,505 — Total Assets $ 2,976,077 $ 2,976,077 $ 569,400 $ 2,406,677 $ — Liabilities Short-term borrowings $ 27,883 $ 27,883 $ — $ 27,883 $ — Long-term borrowings 1,388,548 1,465,489 — 1,465,489 — Securities loaned 754,687 754,687 — 754,687 — Securities sold under agreements to repurchase 390,642 390,642 — 390,642 — Payables to broker dealer and clearing organizations 716,205 716,205 2,925 713,280 — Total Liabilities $ 3,277,965 $ 3,354,906 $ 2,925 $ 3,351,981 $ — Fair value measurements for those items measured on a recurring basis are summarized below as of September 30, 2018 : September 30, 2018 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Counterparty and Cash Collateral Netting Total Fair Value Assets Financial instruments owned, at fair value: Equity securities $ 814,667 $ 1,286,236 $ — $ — $ 2,100,903 U.S. and Non-U.S. government obligations 92,965 21,375 — — 114,340 Corporate Bonds — 68,965 — — 68,965 Exchange traded notes 13,042 48,369 — — 61,411 Currency forwards — 1,929,452 — (1,901,746 ) 27,706 Options 799 — — — 799 921,473 3,354,397 — (1,901,746 ) 2,374,124 Financial instruments owned, pledged as collateral: Equity securities $ 386,731 $ 155,357 $ — $ — $ 542,088 U.S. and Non-U.S. government obligations — — — — — Exchange traded notes 2,790 7,751 — — 10,541 389,521 163,108 — — 552,629 Other Assets Equity investment $ — $ — $ 40,243 $ — $ 40,243 Exchange stock 2,132 — — — 2,132 2,132 — 40,243 — 42,375 Liabilities Financial instruments sold, not yet purchased, at fair value: Equity securities $ 1,092,602 $ 1,162,905 $ — $ — $ 2,255,507 U.S. and Non-U.S. government obligations 82,916 1,227 — — 84,143 Corporate Bonds — 37,865 — — 37,865 Exchange traded notes 874 19,012 — — 19,886 Currency forwards — 1,942,686 — (1,942,686 ) — Options 693 — — — 693 $ 1,177,085 $ 3,163,695 $ — $ (1,942,686 ) $ 2,398,094 Fair value measurements for those items measured on a recurring basis are summarized below as of December 31, 2017 : December 31, 2017 (in thousands) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Counterparty and Cash Collateral Netting Total Fair Value Assets Financial instruments owned, at fair value: Equity securities $ 758,596 $ 1,167,995 $ — $ — $ 1,926,591 Non-U.S. government obligations 5,968 16,815 — — 22,783 Corporate Bonds — 60,975 — — 60,975 Exchange traded notes 13,576 68,819 — — 82,395 Currency forwards — 2,045,487 — (2,027,697 ) 17,790 Options 7,045 — — — 7,045 $ 785,185 $ 3,360,091 $ — $ (2,027,697 ) $ 2,117,579 Financial instruments owned, pledged as collateral: Equity securities $ 410,670 $ 175,581 $ — $ — $ 586,251 U.S. and Non-U.S. government obligations 99 — — — 99 Exchange traded notes 82 8,611 — — 8,693 $ 410,851 $ 184,192 $ — $ — $ 595,043 Other Assets Equity investment $ — $ — $ 40,588 $ — $ 40,588 Exchange stock 1,952 — — — 1,952 Other (1) — 55,824 — — 55,824 $ 1,952 $ 55,824 $ 40,588 $ — $ 98,364 Liabilities Financial instruments sold, not yet purchased, at fair value: Equity securities $ 847,816 $ 1,355,616 $ — $ — $ 2,203,432 U.S. and Non-U.S. government obligations 18,940 12,481 — — 31,421 Corporate Bonds — 81,118 — — 81,118 Exchange traded notes 1,514 54,248 — — 55,762 Currency forwards — 2,032,017 — (2,024,991 ) 7,026 Options 5,839 — — — 5,839 $ 874,109 $ 3,535,480 $ — $ (2,024,991 ) $ 2,384,598 (1) Other primarily consists of a $55.8 million receivable from Bats related to the sale of KCG Hotspot.
Summary of changes in Level 3 financial instruments measured at fair value on a recurring basis	The following presents the changes in Level 3 financial instruments measured at fair value on a recurring basis: Nine Months Ended September 30, 2018 (in thousands) December 31, 2017 Purchases Total Realized and Unrealized Gains / (Losses) Net Transfers into (out of) Level 3 Settlement September 30, 2018 Change in Net Unrealized Gains / (Losses) on Investments still held at September 30, 2018 Assets Other assets: Equity investment $ 40,588 $ — $ (345 ) $ — $ — $ 40,243 $ (345 ) Total $ 40,588 $ — $ (345 ) $ — $ — $ 40,243 $ (345 ) Nine Months Ended September 30, 2017 (in thousands) December 31, 2016 Purchases Total Realized and Unrealized Gains / (Losses) Net Transfers into (out of) Level 3 Settlement September 30, 2017 Change in Net Unrealized Gains / (Losses) on Investments still held at September 30, 2017 Assets Other assets: Equity investment $ 36,031 $ — $ 1,232 $ — $ — $ 37,263 $ 1,232 Other — 3,000 — — — 3,000 — Total $ 36,031 $ 3,000 $ 1,232 $ — $ — $ 40,263 $ 1,232
Summary of netting of certain financial assets and financial liabilities	The following tables set forth the gross and net presentation of certain financial assets and financial liabilities as of September 30, 2018 and December 31, 2017 : September 30, 2018 Gross Amounts of Recognized Assets Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Received Net Amount Offsetting of Financial Assets: Securities borrowed $ 1,305,789 $ — $ 1,305,789 $ (1,268,772 ) $ (6,195 ) $ 30,822 Securities purchased under agreements to resell 10,014 — 10,014 (9,993 ) (21 ) — Trading assets, at fair value: Currency forwards 1,929,452 (1,901,746 ) 27,706 — — 27,706 Options 799 — 799 (799 ) — — Total $ 3,246,054 $ (1,901,746 ) $ 1,344,308 $ (1,279,564 ) $ (6,216 ) $ 58,528 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Pledged Net Amount Offsetting of Financial Liabilities: Securities loaned $ 800,145 $ — $ 800,145 $ (786,922 ) $ (6,195 ) $ 7,028 Securities sold under agreements to repurchase 301,238 — $ 301,238 (301,220 ) (21 ) (3 ) Trading liabilities, at fair value: Currency forwards 1,942,686 (1,942,686 ) — — — Options 693 — 693 (693 ) — — Total $ 3,044,762 $ (1,942,686 ) $ 1,102,076 $ (1,088,835 ) $ (6,216 ) $ 7,025 December 31, 2017 Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Received Net Amount Offsetting of Financial Assets: Securities borrowed $ 1,471,172 $ — $ 1,471,172 $ (1,418,672 ) $ (13,318 ) $ 39,182 Trading assets, at fair value: Currency forwards 2,045,487 (2,027,697 ) 17,790 — — 17,790 Options 7,045 — 7,045 (45 ) — 7,000 Total $ 3,523,704 $ (2,027,697 ) $ 1,496,007 $ (1,418,717 ) $ (13,318 ) $ 63,972 Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Consolidated Statement of Financial Condition Net Amounts of Assets Presented in the Consolidated Statement of Financial Condition Gross Amounts Not Offset In the Statement of Financial Condition (in thousands) Financial Instruments Cash Collateral Pledged Net Amount Offsetting of Financial Liabilities: Securities loaned $ 754,687 $ — $ 754,687 $ (737,731 ) $ (10,776 ) $ 6,180 Securities sold under agreements to repurchase 390,642 — 390,642 (390,642 ) — — Trading liabilities, at fair value: Currency forwards 2,032,017 (2,024,991 ) 7,026 — 7,026 Options 5,839 — 5,839 (56 ) — 5,783 Total $ 3,183,185 $ (2,024,991 ) $ 1,158,194 $ (1,128,429 ) $ (10,776 ) $ 18,989
Summary of gross obligations for repurchase agreement and securities borrowed transactions by remaining contractual maturity and class of collateral pledged	The following table presents gross obligations for securities sold under agreements to repurchase and for securities lending transactions by remaining contractual maturity and the class of collateral pledged: September 30, 2018 Remaining Contractual Maturity (in thousands) Overnight and Continuous Less than 30 days 30 - 60 days 61 - 90 Days Total Repurchase agreements: Equity securities $ — $ 65,000 $ 40,000 $ 160,000 $ 265,000 U.S. and Non-U.S. government obligations 36,238 — — — 36,238 Total $ 36,238 $ 65,000 $ 40,000 $ 160,000 $ 301,238 Securities lending transactions: Equity securities $ 800,145 $ — $ — $ — $ 800,145 Total $ 800,145 $ — $ — $ — $ 800,145 December 31, 2017 Remaining Contractual Maturity (in thousands) Overnight and Continuous Less than 30 days 30 - 60 days 61 - 90 Days Total Repurchase agreements: Equity securities $ — $ 100,000 $ 90,000 $ 200,000 $ 390,000 U.S. and Non-U.S. government obligations 642 — — — 642 Total $ 642 $ 100,000 $ 90,000 $ 200,000 $ 390,642 Securities lending transactions: Equity securities $ 754,687 $ — $ — $ — $ 754,687 Total $ 754,687 $ — $ — $ — $ 754,687

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of fair value of derivative instruments on a gross basis	The fair value of the Company’s derivative instruments on a gross basis consisted of the following at September 30, 2018 and December 31, 2017 : (in thousands) September 30, 2018 December 31, 2017 Derivatives Assets Financial Statements Location Fair Value Notional Fair Value Notional Derivative instruments not designated as hedging instruments: Equities futures Receivables from broker dealers and clearing organizations $ 16,357 $ 3,398,419 $ (505 ) $ 1,985,770 Commodity futures Receivables from broker dealers and clearing organizations 225,449 12,830,011 971 21,231,001 Currency futures Receivables from broker dealers and clearing organizations 21,986 2,672,739 26,548 3,994,412 Fixed income futures Receivables from broker dealers and clearing organizations — 34,186 73 44,395 Options Financial instruments owned 799 139,046 7,045 682,369 Currency forwards Financial instruments owned 1,929,452 138,790,533 2,045,487 124,000,221 Derivatives Liabilities Financial Statements Location Fair Value Notional Fair Value Notional Derivative instruments not designated as hedging instruments: Equities futures Payables to broker dealers and clearing organizations $ (1,687 ) $ 127,500 $ (575 ) $ 142,658 Commodity futures Payables to broker dealers and clearing organizations (276,827 ) 6,058,850 (1,602 ) 130,042 Currency futures Payables to broker dealers and clearing organizations 359 2,566,892 (13,947 ) 7,756,958 Fixed income futures Payables to broker dealers and clearing organizations 1,039 54,534 (1 ) 2,584 Options Financial instruments sold, not yet purchased 693 140,079 5,839 681,147 Currency forwards Financial instruments sold, not yet purchased 1,942,686 138,797,150 2,032,017 123,993,234 Derivative instruments designated as hedging instruments: Currency forwards Financial instruments sold, not yet purchased — — (514 ) 16,115
Schedule of net gain from derivative instruments not designated as hedging instruments	The following table summarizes the net gain from derivative instruments not designated as hedging instruments under ASC 815, which are recorded in trading income, net, and from those designated as hedging instrument under ASC 815, which are recorded in accumulated other comprehensive income in the accompanying condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 2018 and 2017 . Three Months Ended September 30, Nine Months Ended September 30, (in thousands) Financial Statements Location 2018 2017 2018 2017 Derivative instruments not designated as hedging instruments: Futures Trading income, net $ 103,950 $ 35,097 $ (325,556 ) $ 249,274 Currency forwards Trading income, net (47,882 ) 8,950 148,706 3,135 Options Trading income, net 1,161 21,120 (7,575 ) 21,119 Others Trading income, net — 125 — — $ 57,229 $ 65,292 $ (184,425 ) $ 273,528 Derivative instruments designated as hedging instruments: Foreign exchange - forward contract Accumulated other comprehensive income $ 699 $ 19 $ 855 $ 19

Revenues from Contracts with _2

Revenues from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	The following tables present the Company’s revenue from contracts with customers disaggregated by the services described above, by timing of revenue recognition, reconciled to the Company’s reportable segments, as well as disaggregation of the Company’s revenues by services and geographic region, for the three and nine months ended September 30, 2018 : Three Months Ended September 30, 2018 (in thousands) Market Making Execution Services Corporate Total Revenues from contract with Customers: Commissions, net $ 6,587 $ 33,332 $ — $ 39,919 Technology services — 333 — 333 Total revenue from contract with customers 6,587 33,665 — 40,252 Other sources of revenue 257,783 541 (3,453 ) 254,871 Total Revenues 264,370 34,206 (3,453 ) 295,123 Timing of revenue recognition: Services transferred at a point in time 264,370 33,873 (3,453 ) 294,790 Services transferred over time — 333 — 333 Total Revenues $ 264,370 $ 34,206 $ (3,453 ) $ 295,123 Nine Months Ended September 30, 2018 (in thousands) Market Making Execution Services Corporate Total Revenues from contract with Customers: Commissions, net $ 21,886 $ 113,786 $ — $ 135,672 Technology services — 4,989 — 4,989 Total revenue from contract with customers 21,886 118,775 — 140,661 Other sources of revenue 962,715 339,984 (5,057 ) 1,297,642 Total Revenues 984,601 458,759 (5,057 ) 1,438,303 Timing of revenue recognition: Services transferred at a point in time 984,601 453,770 (5,057 ) 1,433,314 Services transferred over time — 4,989 — 4,989 Total Revenues $ 984,601 $ 458,759 $ (5,057 ) $ 1,438,303

Share-based Compensation (Table

Share-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Non-qualified stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of activity	The following table summarizes activity related to stock options for the nine months ended September 30, 2018 and 2017 : Options Outstanding Options Exercisable Number of Options Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Life Number of Options Weighted Average Exercise Price Per Share At December 31, 2016 8,234,000 $ 19.00 8.29 2,058,500 $ 19.00 Granted — — — — — Exercised — — — — — Forfeited or expired (401,000 ) — — — — At September 30, 2017 7,833,000 $ 19.00 7.55 3,916,500 $ 19.00 At December 31, 2017 7,783,000 $ 19.00 7.29 3,891,500 $ 19.00 Granted — — — — — Exercised (4,086,558 ) 19.00 — (4,086,558 ) 19.00 Forfeited or expired (83,750 ) — — — — At September 30, 2018 3,612,692 $ 19.00 6.55 1,741,942 $ 19.00
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of activity related to restricted stock units	The following table summarizes activity related to the RSUs: Number of Shares Weighted Average Fair Value At December 31, 2016 1,573,441 $ 18.28 Granted 34,825 17.95 Forfeited (212,729 ) 18.46 Vested (58,536 ) 19.22 At September 30, 2017 1,337,001 18.21 At December 31, 2017 853,047 17.94 Granted 1,265,899 20.89 Forfeited (127,493 ) 18.30 Vested (83,942 ) 18.25 At September 30, 2018 1,907,511 $ 19.86

Regulatory Requirement (Tables)

Regulatory Requirement (Tables)	9 Months Ended
	Sep. 30, 2018
Regulatory Capital Requirements [Abstract]
Schedule of regulatory capital and regulatory capital requirements	The regulatory capital and regulatory capital requirements of these subsidiaries as of September 30, 2018 were as follows: (in thousands) Regulatory Capital Regulatory Capital Requirement Excess Regulatory Capital Virtu Americas LLC $ 337,534 $ 4,086 $ 333,448 Virtu Financial BD LLC 82,546 1,000 81,546 Virtu Financial Capital Markets LLC 9,020 1,000 8,020 The regulatory capital and regulatory capital requirements of these subsidiaries as of December 31, 2017 were as follows: (in thousands) Regulatory Capital Regulatory Capital Requirement Excess Regulatory Capital Virtu Americas LLC $ 379,875 $ 1,000 $ 378,875 Virtu Financial BD LLC 40,683 1,000 39,683 Virtu Financial Capital Markets LLC 8,308 5,114 3,194

Geographic Information and Bu_2

Geographic Information and Business Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of total revenues by geographic area	The following table presents total revenues by geographic area for the three and nine months ended September 30, 2018 and 2017 : Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2018 2017 2018 2017 Revenues: United States $ 245,631 $ 218,042 $ 1,266,047 $ 399,361 Ireland 21,938 17,874 60,563 79,129 United Kingdom 479 10,485 15,324 10,485 Singapore 26,921 22,601 95,757 72,210 Others 154 2,284 612 2,276 Total revenues $ 295,123 $ 271,286 $ 1,438,303 $ 563,461
Schedule of revenues, income (loss) before income taxes (“Pre-tax earnings”) and total assets by segment	The Company’s total revenues and income before income taxes and noncontrolling interest (“Pre-tax earnings”) by segment for the three months ended September 30, 2018 and 2017 are summarized in the following table: (in thousands) Market Making Execution Services Corporate (1) Consolidated Total 2018: Total revenue $ 264,370 $ 34,206 $ (3,453 ) $ 295,123 Income before income taxes and noncontrolling interest 39,744 129 (10,448 ) 29,425 2017: Total revenue 228,582 39,077 3,627 271,286 Income (loss) before income taxes and noncontrolling interest (19,322 ) (6,017 ) (21,156 ) (46,495 ) (1) Amounts shown in the Corporate segment include eliminations of income statement and balance sheet items included in the Company's other segments. The Company's Pre-tax earnings by segment for the nine months ended September 30, 2018 and 2017 are summarized in the following table: (in thousands) Market Making Execution Services Corporate (1) Consolidated Total 2018 Total revenue $ 984,601 $ 458,759 $ (5,057 ) $ 1,438,303 Income before income taxes and noncontrolling interest 262,910 331,703 (47,028 ) 547,585 2017 Total revenue 514,823 44,964 3,674 563,461 Income (loss) before income taxes and noncontrolling interest 17,241 (4,913 ) (29,749 ) (17,421 ) (1) Amounts shown in the Corporate segment include eliminations of income statement and balance sheet items included in the Company's other segments.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details) $ in Thousands	Jan. 02, 2018USD ($)	Jul. 19, 2017businesssegment	Sep. 30, 2017segment	Sep. 30, 2018
Organization, Consolidation And Presentation Of Financial Statements [Line Items]
Number of businesses managed and operated | business		1
Number of operating segments | segment		1	3
Disposal Group, Disposed of by Sale, Not Discontinued Operations | BondPoint
Organization, Consolidation And Presentation Of Financial Statements [Line Items]
Proceeds from sale of business | $	$ 400,192
Virtu Financial
Organization, Consolidation And Presentation Of Financial Statements [Line Items]
Ownership interest (as a percent)				56.60%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Securities Borrowed and Securities Loaned (Details)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Minimum initial collateral advanced or received expressed as a percentage of fair value of the underlying securities borrowed or loaned	102.00%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property, Equipment and Occupancy (Details) - Furniture, fixtures and equipment	9 Months Ended
	Sep. 30, 2018
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	7 years

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Capitalized Software (Details) - Capitalized software	9 Months Ended
	Sep. 30, 2018
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	1 year 6 months
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years 6 months

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Share-Based Compensation (Details)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Number of days prior to the grant that common stock and restricted stock units fair value is determined based on	3 days

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Variable Interest Entities (Details) $ in Thousands	1 Months Ended
	Oct. 31, 2016party	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Variable Interest Entity [Line Items]
Carrying Amount, Asset		$ 18,669	$ 18,799
Carrying Amount, Liability		0	0
Maximum Exposure to Loss		18,669	18,799
VIEs' assets		$ 48,557	$ 41,936
JV building microwave communication networks in US and Asia
Variable Interest Entity [Line Items]
Number of other investors in JV | party	9
Ownership of voting shares of JV held be each investor (as a percent)		11.00%
Ownership of equity of JV held be each investor (as a percent)		11.00%
JV building microwave communication networks in US and Europe
Variable Interest Entity [Line Items]
Ownership of voting shares (as a percent)		50.00%
Ownership interest (as a percent)		50.00%

Acquisition of KCG Holdings, _3

Acquisition of KCG Holdings, Inc. - Narrative (Details) - USD ($)	Aug. 10, 2017	Jul. 21, 2017	Jul. 20, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Aggregate purchase price					$ 735,974,000
Goodwill				$ 836,583,000		$ 844,883,000
Deferred tax assets				178,087,000		125,760,000
Market Making
Business Acquisition [Line Items]
Goodwill			$ 96,200,000	$ 755,292,000		$ 755,292,000
Technology and Execution Services
Business Acquisition [Line Items]
Goodwill			$ 32,100,000
Senior Secured Notes Due 2020
Business Acquisition [Line Items]
Interest rate		6.875%
Redemption price as a percentage of the principal amount		103.438%
Face amount		$ 465,000,000
Temasek Investment
Business Acquisition [Line Items]
Other offering costs	$ 7,800,000
Class A
Business Acquisition [Line Items]
Common stock, par value (in dollars per share)				$ 0.00001		$ 0.00001
Number of shares of stock issued				10,518,750
Class A | NIH Investment Agreement
Business Acquisition [Line Items]
Number of shares of stock issued	338,124
Aggregate purchase price	$ 5,200,000
KCG
Business Acquisition [Line Items]
Common stock, par value (in dollars per share)			$ 0.01
Right to receive cash (in dollars per share)			$ 20
Cash purchase price			$ 1,400,000,000
Fair value (in dollars per share)			$ 20
Goodwill			$ 128,286,000
Deferred tax assets			$ 23,900,000
KCG | NIH Investment Agreement
Business Acquisition [Line Items]
Number of shares of stock issued			39,725,979
Aggregate purchase price			$ 613,500,000
KCG | Class A | Aranda
Business Acquisition [Line Items]
Number of shares of stock issued			6,346,155
Aggregate purchase price			$ 99,000,000
KCG | Class A | Temasek Investment
Business Acquisition [Line Items]
Number of shares of stock issued	1,666,666
Aggregate purchase price	$ 26,000,000
KCG | Class A | NIH Investment Agreement
Business Acquisition [Line Items]
Number of shares of stock issued	338,124
Aggregate purchase price	$ 5,200,000

Acquisition of KCG Holdings, _4

Acquisition of KCG Holdings, Inc. - Intangible Assets (Details) - USD ($) $ in Thousands	Jul. 20, 2017	Sep. 30, 2018	Dec. 31, 2017
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets		$ 90,069	$ 111,224
Goodwill		836,583	844,883
Customer relationships
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets		44,115	47,178
Favorable leases
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets		$ 4,875	$ 5,487
KCG
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets	$ 174,995
Goodwill	128,286
Total	303,281
KCG | Technology
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets	67,700
KCG | Customer relationships
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets	94,000
KCG | Trade names
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets	$ 1,000
Amortization Years	10 years
KCG | Favorable leases
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets	$ 5,895
KCG | Exchange memberships
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Intangible assets	$ 6,400
KCG | Minimum | Technology
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Amortization Years	1 year
KCG | Minimum | Customer relationships
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Amortization Years	13 years
KCG | Minimum | Favorable leases
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Amortization Years	2 years
KCG | Maximum | Technology
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Amortization Years	6 years
KCG | Maximum | Customer relationships
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Amortization Years	17 years
KCG | Maximum | Favorable leases
Amounts preliminarily allocated to intangible assets, the amortization period and goodwill
Amortization Years	15 years

Sale of BondPoint - Narrative (

Sale of BondPoint - Narrative (Details) - BondPoint - Disposal Group, Disposed of by Sale, Not Discontinued Operations - USD ($) $ in Thousands	Jan. 02, 2018	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of BondPoint	$ 400,192
Transaction costs	8,568
Professional fees	7,100
Compensation expense	1,400
Gain on sale of BondPoint, net of transaction costs	$ 337,550	$ 337,600

Sale of BondPoint - Summary of

Sale of BondPoint - Summary of Carrying Value and Gain on Sale (Details) - USD ($) $ in Thousands	Jan. 02, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Assets and liabilities of businesses held for sale
Goodwill adjustment allocated to BondPoint		$ 8,300
Gain on sale of BondPoint, net of transaction costs		335,211	$ 0
BondPoint | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of BondPoint	$ 400,192
Assets and liabilities of businesses held for sale
Goodwill adjustment allocated to BondPoint	8,300
Gain on sale of BondPoint	337,550	$ 337,600
Transaction costs	8,568
Gain on sale of BondPoint, net of transaction costs	$ 328,982
BondPoint | Held for Sale
Assets and liabilities of businesses held for sale
Receivables from broker dealers and clearing organizations				$ 3,383
Intangibles and other assets				51,687
Liabilities				(728)
Total carrying value of BondPoint				$ 54,342

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reconciliation of net income before minority interest to net income available for common stockholders
Income (loss) before income taxes and noncontrolling interest	$ 29,425	$ (46,495)	$ 547,585	$ (17,421)
Provision for (benefit from) income taxes	13,815	(6,505)	75,330	(2,918)
Net income (loss)	15,610	(39,990)	472,255	(14,503)
Noncontrolling interest	(6,998)	26,472	(263,682)	6,466
Net income (loss) available for common stockholders	$ 8,612	$ (13,518)	$ 208,573	$ (8,037)

Earnings Per Share - Basic (Det

Earnings Per Share - Basic (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share:
Net income (loss) available for common stockholders	$ 8,612	$ (13,518)	$ 208,573	$ (8,037)
Less: Dividends and undistributed earnings allocated to participating securities	(418)	(314)	(4,029)	(997)
Net income (loss) available for common stockholders, net of dividends and undistributed earnings allocated to participating securities	$ 8,194	$ (13,832)	$ 204,544	$ (9,034)
Weighted average shares of common stock outstanding:
Outstanding (in shares)	106,692,034	79,199,142	99,038,084	53,520,346
Basic earnings per share (in dollars per share)	$ 0.08	$ (0.17)	$ 2.07	$ (0.17)
Class A
Weighted average shares of common stock outstanding:
Outstanding (in shares)	106,692,034	79,199,142	99,038,084	53,520,346

Earnings Per Share - Diluted (D

Earnings Per Share - Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Diluted earnings per share:
Net income (loss) available for common stockholders, net of dividends and undistributed earnings allocated to participating securities	$ 8,194	$ (13,832)	$ 204,544	$ (9,034)
Weighted average shares of common stock outstanding:
Issued and outstanding (in shares)	106,692,034	79,199,142	99,038,084	53,520,346
Weighted average shares of common stock outstanding (in shares)	107,128,206	79,199,142	100,468,860	53,520,346
Diluted earnings per share (in dollars per share)	$ 0.08	$ (0.17)	$ 2.04	$ (0.17)
Anti-dilutive shares excluded from computation of EPS		1,578,617		1,704,307
Class A
Weighted average shares of common stock outstanding:
Issued and outstanding (in shares)	106,692,034	79,199,142	99,038,084	53,520,346
Issuable pursuant to 2015 Management Incentive Plan (in shares)	436,172	0	1,430,776	0
Weighted average shares of common stock outstanding (in shares)	107,128,206	79,199,142	100,468,860	53,520,346

Tax Receivable Agreements (Deta

Tax Receivable Agreements (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Apr. 15, 2015	Sep. 30, 2018	May 31, 2018	Feb. 28, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Tax Receivable Agreements [Abstract]
Payment on applicable cash tax savings (as a percent)		85.00%
First payment made			$ 12,300		$ 7,000
Minimum tax receivable agreement obligation over the agreed period		$ 3,600
Maximum tax receivable agreement obligation over the agreed period		$ 16,000
Period over which the obligations are to be settled		15 years
Reduction of paid-in capital for the difference between TRA liability and related deferred tax asset.		$ 16,400
Deferred tax asset from tax receivable agreement				$ 61,100
Tax receivable agreement obligations			199,264	64,600		$ 199,264		$ 147,040
Issuance of tax receivable agreements in connection with employee exchange				$ 3,500		3,439	$ (1,355)
U.S. federal statutory rate (as a percent)	21.00%							35.00%
Reduction to additional paid-in capital as a result of differences between estimate and tax returns								$ 86,600
Deferred tax assets			$ 153,900			$ 153,900		$ 101,600

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Narrative (Details)	Jan. 02, 2018USD ($)	Jul. 19, 2017businesssegment	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)segment	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets [Line Items]
Amortization expense relating to finite-lived intangible assets			$ 6,367,000	$ 6,440,000	$ 20,042,000	$ 6,546,000
Intangible assets			90,069,000		90,069,000		$ 111,224,000
Goodwill [Line Items]
Number of businesses managed and operated | business		1
Number of operating segments | segment		1		3
Goodwill			836,583,000		836,583,000		844,883,000
Goodwill adjustment allocated to BondPoint					8,300,000
Goodwill impairment					0	$ 0
Leases
Finite-Lived Intangible Assets [Line Items]
Intangible assets							$ 1,403,000
Joint Venture | Leases
Finite-Lived Intangible Assets [Line Items]
Intangible assets			$ 1,100,000		$ 1,100,000
BondPoint | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Goodwill [Line Items]
Goodwill adjustment allocated to BondPoint	$ 8,300,000

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Changes in goodwill
Balance at the beginning of the period	$ 844,883
Goodwill adjustment allocated to BondPoint	(8,300)
Balance at the end of the period	836,583
Market Making
Changes in goodwill
Balance at the beginning of the period	755,292
Goodwill adjustment allocated to BondPoint	0
Balance at the end of the period	755,292
Execution Services
Changes in goodwill
Balance at the beginning of the period	89,591
Goodwill adjustment allocated to BondPoint	(8,300)
Balance at the end of the period	81,291
Corporate
Changes in goodwill
Balance at the beginning of the period	0
Goodwill adjustment allocated to BondPoint	0
Balance at the end of the period	$ 0

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Acquired Intangible Assets [Line Items]
Accumulated Amortization	$ 142,564	$ 123,408
Net Carrying Amount	90,069	111,224
Gross Carrying Amount	232,633	234,633
Net Carrying Amount	90,069	111,224
Exchange memberships
Acquired Intangible Assets [Line Items]
Indefinite-lived intangibles	5,838	5,838
Purchased technology
Acquired Intangible Assets [Line Items]
Gross Carrying Amount	110,000	110,000
Accumulated Amortization	110,000	110,000
Net Carrying Amount	$ 0	$ 0
Purchased technology | Minimum
Acquired Intangible Assets [Line Items]
Useful Lives (Years)	1 year 4 months 24 days	1 year 4 months 24 days
Purchased technology | Maximum
Acquired Intangible Assets [Line Items]
Useful Lives (Years)	2 years 6 months	2 years 6 months
ETF issuer relationships
Acquired Intangible Assets [Line Items]
Gross Carrying Amount	$ 950	$ 950
Accumulated Amortization	638	559
Net Carrying Amount	$ 312	$ 391
Useful Lives (Years)	9 years	9 years
ETF buyer relationships
Acquired Intangible Assets [Line Items]
Gross Carrying Amount	$ 950	$ 950
Accumulated Amortization	639	559
Net Carrying Amount	$ 311	$ 390
Useful Lives (Years)	9 years	9 years
Leases
Acquired Intangible Assets [Line Items]
Gross Carrying Amount		$ 1,800
Accumulated Amortization		397
Net Carrying Amount		$ 1,403
Useful Lives (Years)		3 years
FCC licenses
Acquired Intangible Assets [Line Items]
Gross Carrying Amount		$ 200
Accumulated Amortization		19
Net Carrying Amount		$ 181
Useful Lives (Years)		7 years
Technology
Acquired Intangible Assets [Line Items]
Gross Carrying Amount	$ 60,000	$ 60,000
Accumulated Amortization	25,382	9,644
Net Carrying Amount	$ 34,618	$ 50,356
Technology | Minimum
Acquired Intangible Assets [Line Items]
Useful Lives (Years)	1 year	1 year
Technology | Maximum
Acquired Intangible Assets [Line Items]
Useful Lives (Years)	6 years	6 years
Customer relationships
Acquired Intangible Assets [Line Items]
Gross Carrying Amount	$ 49,000	$ 49,000
Accumulated Amortization	4,885	1,822
Net Carrying Amount	$ 44,115	$ 47,178
Useful Lives (Years)	12 years	12 years
Favorable occupancy leases
Acquired Intangible Assets [Line Items]
Gross Carrying Amount	$ 5,895	$ 5,895
Accumulated Amortization	1,020	408
Net Carrying Amount	$ 4,875	$ 5,487
Favorable occupancy leases | Minimum
Acquired Intangible Assets [Line Items]
Useful Lives (Years)	3 years	3 years
Favorable occupancy leases | Maximum
Acquired Intangible Assets [Line Items]
Useful Lives (Years)	15 years	15 years

Receivables from_Payables to _3

Receivables from/Payables to Broker-Dealers and Clearing Organizations (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Due from prime brokers	$ 370,599	$ 219,573
Deposits with clearing organizations	95,817	112,847
Net equity with futures commission merchants	260,705	203,711
Unsettled trades with clearing organization	150,265	173,778
Securities failed to deliver	229,944	248,088
Commissions and fees	8,434	14,021
Total receivables from broker-dealers and clearing organizations	1,115,764	972,018
Liabilities
Due to prime brokers	398,181	197,439
Net equity with futures commission merchants	53,986	44,526
Unsettled trades with clearing organization	470,665	420,029
Securities failed to receive	28,077	51,143
Commissions and fees	1,434	3,068
Total payables to broker-dealers and clearing organizations	952,343	716,205
Outstanding principal balance	$ 144,700	$ 205,700

Collateralized Transactions (De

Collateralized Transactions (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Securities received as collateral:
Securities borrowed	$ 1,261,472	$ 1,415,793
Securities purchased under agreements to resell	10,014	0
Securities received as collateral	1,271,486	1,415,793
Financial Instruments Owned and Pledged as Collateral [Line Items]
Financial instruments owned and pledged	552,629	595,043
Equities
Financial Instruments Owned and Pledged as Collateral [Line Items]
Financial instruments owned and pledged	542,088	586,251
U.S. and Non-U.S. government obligations
Financial Instruments Owned and Pledged as Collateral [Line Items]
Financial instruments owned and pledged	0	99
Exchange traded notes
Financial Instruments Owned and Pledged as Collateral [Line Items]
Financial instruments owned and pledged	$ 10,541	$ 8,693

Borrowings - Broker-Dealer Cred

Borrowings - Broker-Dealer Credit Facilities, Narrative (Details)	Nov. 03, 2017USD ($)borrowing_basebroker_dealer	Sep. 30, 2018USD ($)broker_dealer	Dec. 31, 2017USD ($)	Nov. 02, 2017USD ($)
Line of Credit Facility [Line Items]
Number of borrowing bases | borrowing_base	2
Number of broker-dealer subsidiaries	3	3
LIBOR
Line of Credit Facility [Line Items]
Interest rate margin (as a percent)	1.25%
Broker-dealer credit facilities
Line of Credit Facility [Line Items]
Number of secured credit facilities		2
Aggregate borrowing | $	$ 500,000,000	$ 700,000,000	$ 650,000,000	$ 25,000,000
Number of broker-dealer subsidiaries the committed facility is available to	2
Maximum borrowing capacity | $	$ 100,000,000			$ 40,000,000
Commitment fee (as a percent)	0.50%
Broker-dealer credit facilities | LIBOR
Line of Credit Facility [Line Items]
Interest rate margin (as a percent)	2.50%
Broker-dealer credit facility on an uncommitted basis
Line of Credit Facility [Line Items]
Number of secured credit facilities		1
Aggregate borrowing | $		$ 200,000,000	$ 150,000,000

Borrowings - Broker-Dealer Cr_2

Borrowings - Broker-Dealer Credit Facilities Carrying Values, Net (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017	Nov. 03, 2017	Nov. 02, 2017
Line of Credit Facility [Line Items]
Borrowing Outstanding	$ 930,783,000
Outstanding Borrowings, net	$ 904,027,000	$ 1,388,548,000
Uncommitted facility
Line of Credit Facility [Line Items]
Interest Rate	3.17%	2.42%
Financing Available	$ 200,000,000	$ 150,000,000
Borrowing Outstanding	10,000,000	25,000,000
Deferred Debt Issuance Cost	(1,081,000)	0
Outstanding Borrowings, net	$ 8,919,000	$ 25,000,000
Revolving credit facility
Line of Credit Facility [Line Items]
Interest Rate	3.51%	2.81%
Financing Available	$ 500,000,000	$ 500,000,000
Borrowing Outstanding	7,000,000	7,000,000
Deferred Debt Issuance Cost	(1,352,000)	(4,117,000)
Outstanding Borrowings, net	5,648,000	2,883,000
Broker-dealer credit facilities
Line of Credit Facility [Line Items]
Financing Available	700,000,000	650,000,000	$ 500,000,000	$ 25,000,000
Borrowing Outstanding	17,000,000	32,000,000
Deferred Debt Issuance Cost	(2,433,000)	(4,117,000)
Outstanding Borrowings, net	$ 14,567,000	$ 27,883,000

Borrowings - Interest Expense o

Borrowings - Interest Expense on Broker-Dealer Facilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Line of Credit Facility [Line Items]
Interest expense	$ 17,709	$ 24,593	$ 55,536	$ 40,141
Broker-dealer credit facilities
Line of Credit Facility [Line Items]
Interest expense	488	407	1,670	1,368
Uncommitted facility
Line of Credit Facility [Line Items]
Interest expense	428	405	1,458	1,335
Committed facility
Line of Credit Facility [Line Items]
Interest expense	0	2	0	33
Revolving credit facility
Line of Credit Facility [Line Items]
Interest expense	$ 60	$ 0	$ 212	$ 0

Borrowings - Short-Term Credit

Borrowings - Short-Term Credit Facilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Short-term Debt [Line Items]
Borrowing Outstanding	$ 930,783		$ 930,783
Interest expense	$ 17,709	$ 24,593	$ 55,536	$ 40,141
Short-Term Credit Facilities
Short-term Debt [Line Items]
Weighted Average Interest Rate	4.27%		4.27%		3.86%
Financing Available	$ 566,000		$ 566,000		$ 543,000
Borrowing Outstanding	144,660		144,660		$ 205,677
Interest expense	$ 1,500	$ 1,400	$ 5,000	$ 4,800

Borrowings - Long-Term Borrowin

Borrowings - Long-Term Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Jun. 16, 2017
Line of Credit Facility [Line Items]
Outstanding Principal	$ 930,783
Outstanding Borrowings, net	$ 904,027	$ 1,388,548
Senior Secured Second Lien Notes
Line of Credit Facility [Line Items]
Interest rate			6.75%
Senior Secured Credit Facility
Line of Credit Facility [Line Items]
Interest rate	5.09%	5.13%
Outstanding Principal	$ 400,000	$ 900,000
Discount	(360)	(999)
Deferred Debt Issuance Cost	(7,267)	(18,504)
Outstanding Borrowings, net	$ 392,373	$ 880,497
Senior Secured Credit Facility | Senior Secured Second Lien Notes
Line of Credit Facility [Line Items]
Interest rate	6.75%	6.75%
Outstanding Principal	$ 500,000	$ 500,000
Discount	0	0
Deferred Debt Issuance Cost	(19,099)	(22,961)
Outstanding Borrowings, net	$ 480,901	$ 477,039
SBI Bonds
Line of Credit Facility [Line Items]
Interest rate	5.00%	5.00%
Outstanding Principal	$ 30,783	$ 31,059
Discount	0	0
Deferred Debt Issuance Cost	(30)	(47)
Outstanding Borrowings, net	30,753	31,012
Total Long-term borrowings
Line of Credit Facility [Line Items]
Outstanding Principal	930,783	1,431,059
Discount	(360)	(999)
Deferred Debt Issuance Cost	(26,396)	(41,512)
Outstanding Borrowings, net	$ 904,027	$ 1,388,548

Borrowings - Fourth Amended and

Borrowings - Fourth Amended and Restated Credit Agreement (Details) - USD ($) $ in Thousands	Nov. 03, 2017	Sep. 30, 2018	Jan. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Outstanding principal amount		$ 930,783		$ 930,783		$ 930,783
Repayments of long-term debt				500,000	$ 206,473
LIBOR
Debt Instrument [Line Items]
Interest rate margin (as a percent)	1.25%
Senior Secured Credit Facility Fourth Amendment
Debt Instrument [Line Items]
Outstanding principal amount		$ 400,000		400,000		400,000	$ 1,150,000
Repayments of long-term debt				500,000		$ 750,000
Accelerated unamortized financing costs				$ 11,700
Senior Secured Credit Facility Fourth Amendment | LIBOR
Debt Instrument [Line Items]
Interest rate margin (as a percent)		2.75%	3.25%

Borrowings - Senior Secured Sec

Borrowings - Senior Secured Second Lien Notes (Details) - Senior Secured Second Lien Notes	Jun. 16, 2017USD ($)
Debt Instrument [Line Items]
Face amount	$ 500,000,000
Interest rate	6.75%

Borrowings - SBI Bonds (Details

Borrowings - SBI Bonds (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2018JPY (¥)	Dec. 31, 2017USD ($)	Dec. 31, 2017JPY (¥)	Jul. 25, 2016USD ($)	Jul. 25, 2016JPY (¥)
Debt Instrument [Line Items]
Outstanding principal amount	$ 930,783	$ 930,783
SBI Bonds
Debt Instrument [Line Items]
Outstanding principal amount	30,783	30,783		$ 31,059
VFH | SBI Bonds
Debt Instrument [Line Items]
Face amount						$ 33,100	¥ 3,500,000,000
Outstanding principal amount	30,800	30,800	¥ 3,500,000,000	$ 31,100	¥ 3,500,000,000
Gain (loss) due to change in currency rates	$ (900)	$ (300)

Borrowings - Future Minimum Pri

Borrowings - Future Minimum Principal Payments (Details) $ in Thousands	Sep. 30, 2018USD ($)
Debt Disclosure [Abstract]
2,018	$ 0
2,019	0
2,020	30,783
2021 and thereafter	900,000
Total principal of long-term borrowings	$ 930,783

Financial Assets and Liabilit_3

Financial Assets and Liabilities - Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Assets
Financial instruments owned, at fair value	$ 2,374,124	$ 2,117,579
Financial instruments owned and pledged	552,629	595,043
Other assets	42,375	98,364
Liabilities
Financial instruments sold, not yet purchased	2,398,094	2,384,598
Equities
Assets
Financial instruments owned and pledged	542,088	586,251
U.S. and Non-U.S. government obligations
Assets
Financial instruments owned and pledged	0	99
Exchange traded notes
Assets
Financial instruments owned and pledged	10,541	8,693
Fair value measurements measured on a recurring basis
Assets
Financial instruments owned, at fair value, counterparty and cash collateral netting	(1,901,746)
Liabilities
Financial instruments sold, not yet purchased, at fair value, counterparty and cash collateral netting	(1,942,686)
Fair value measurements measured on a recurring basis | Currency forwards
Assets
Financial instruments owned, at fair value, counterparty and cash collateral netting	(1,901,746)
Liabilities
Financial instruments sold, not yet purchased, at fair value, counterparty and cash collateral netting	(1,942,686)
Fair value measurements measured on a recurring basis | Fair Value
Assets
Financial instruments owned, at fair value	2,374,124	2,117,579
Financial instruments owned and pledged	552,629	595,043
Other assets	42,375	98,364
Liabilities
Financial instruments sold, not yet purchased	2,398,094	2,384,598
Fair value measurements measured on a recurring basis | Fair Value | Currency forwards
Assets
Financial instruments owned, at fair value	27,706	17,790
Liabilities
Financial instruments sold, not yet purchased	0	7,026
Fair value measurements measured on a recurring basis | Fair Value | Options
Assets
Financial instruments owned, at fair value	799	7,045
Liabilities
Financial instruments sold, not yet purchased	693	5,839
Fair value measurements measured on a recurring basis | Fair Value | Equities
Assets
Financial instruments owned, at fair value	2,100,903	1,926,591
Financial instruments owned and pledged	542,088	586,251
Liabilities
Financial instruments sold, not yet purchased	2,255,507	2,203,432
Fair value measurements measured on a recurring basis | Fair Value | U.S. and Non-U.S. government obligations
Assets
Financial instruments owned, at fair value	114,340
Financial instruments owned and pledged	0	99
Liabilities
Financial instruments sold, not yet purchased	84,143	31,421
Fair value measurements measured on a recurring basis | Fair Value | Non-U.S. government obligations
Assets
Financial instruments owned, at fair value		22,783
Fair value measurements measured on a recurring basis | Fair Value | Corporate Bonds
Assets
Financial instruments owned, at fair value	68,965	60,975
Liabilities
Financial instruments sold, not yet purchased	37,865	81,118
Fair value measurements measured on a recurring basis | Fair Value | Exchange traded notes
Assets
Financial instruments owned, at fair value	61,411	82,395
Financial instruments owned and pledged	10,541	8,693
Liabilities
Financial instruments sold, not yet purchased	19,886	55,762
Fair value measurements measured on a recurring basis | Fair Value | Equity investment
Assets
Other assets	40,243	40,588
Fair value measurements measured on a recurring basis | Fair Value | Exchange stock
Assets
Other assets	2,132	1,952
Fair value measurements measured on a recurring basis | Fair Value | Other
Assets
Other assets		55,824
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Financial instruments owned, at fair value	921,473	785,185
Financial instruments owned and pledged	389,521	410,851
Other assets	2,132	1,952
Liabilities
Financial instruments sold, not yet purchased	1,177,085	874,109
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Currency forwards
Assets
Financial instruments owned, at fair value	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Options
Assets
Financial instruments owned, at fair value	799	7,045
Liabilities
Financial instruments sold, not yet purchased	693	5,839
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equities
Assets
Financial instruments owned, at fair value	814,667	758,596
Financial instruments owned and pledged	386,731	410,670
Liabilities
Financial instruments sold, not yet purchased	1,092,602	847,816
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. and Non-U.S. government obligations
Assets
Financial instruments owned, at fair value	92,965
Financial instruments owned and pledged	0	99
Liabilities
Financial instruments sold, not yet purchased	82,916	18,940
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S. government obligations
Assets
Financial instruments owned, at fair value		5,968
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate Bonds
Assets
Financial instruments owned, at fair value	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Exchange traded notes
Assets
Financial instruments owned, at fair value	13,042	13,576
Financial instruments owned and pledged	2,790	82
Liabilities
Financial instruments sold, not yet purchased	874	1,514
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity investment
Assets
Other assets	0	0
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Exchange stock
Assets
Other assets	2,132	1,952
Fair value measurements measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other
Assets
Other assets		0
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Financial instruments owned, at fair value	3,354,397	3,360,091
Financial instruments owned, at fair value, counterparty and cash collateral netting		(2,027,697)
Financial instruments owned and pledged	163,108	184,192
Other assets	0	55,824
Liabilities
Financial instruments sold, not yet purchased	3,163,695	3,535,480
Financial instruments sold, not yet purchased, at fair value, counterparty and cash collateral netting		(2,024,991)
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Currency forwards
Assets
Financial instruments owned, at fair value	1,929,452	2,045,487
Financial instruments owned, at fair value, counterparty and cash collateral netting		(2,027,697)
Liabilities
Financial instruments sold, not yet purchased	1,942,686	2,032,017
Financial instruments sold, not yet purchased, at fair value, counterparty and cash collateral netting		(2,024,991)
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Options
Assets
Financial instruments owned, at fair value	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Equities
Assets
Financial instruments owned, at fair value	1,286,236	1,167,995
Financial instruments owned and pledged	155,357	175,581
Liabilities
Financial instruments sold, not yet purchased	1,162,905	1,355,616
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | U.S. and Non-U.S. government obligations
Assets
Financial instruments owned, at fair value	21,375
Financial instruments owned and pledged	0	0
Liabilities
Financial instruments sold, not yet purchased	1,227	12,481
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Non-U.S. government obligations
Assets
Financial instruments owned, at fair value		16,815
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate Bonds
Assets
Financial instruments owned, at fair value	68,965	60,975
Liabilities
Financial instruments sold, not yet purchased	37,865	81,118
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Exchange traded notes
Assets
Financial instruments owned, at fair value	48,369	68,819
Financial instruments owned and pledged	7,751	8,611
Liabilities
Financial instruments sold, not yet purchased	19,012	54,248
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Equity investment
Assets
Other assets	0	0
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Exchange stock
Assets
Other assets	0	0
Fair value measurements measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Other
Assets
Other assets		55,824
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3)
Assets
Financial instruments owned, at fair value	0	0
Financial instruments owned and pledged	0	0
Other assets	40,243	40,588
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Currency forwards
Assets
Financial instruments owned, at fair value	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Options
Assets
Financial instruments owned, at fair value	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Equities
Assets
Financial instruments owned, at fair value	0	0
Financial instruments owned and pledged	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | U.S. and Non-U.S. government obligations
Assets
Financial instruments owned, at fair value	0
Financial instruments owned and pledged	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Non-U.S. government obligations
Assets
Financial instruments owned, at fair value		0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Corporate Bonds
Assets
Financial instruments owned, at fair value	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Exchange traded notes
Assets
Financial instruments owned, at fair value	0	0
Financial instruments owned and pledged	0	0
Liabilities
Financial instruments sold, not yet purchased	0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Equity investment
Assets
Other assets	40,243	40,588
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Exchange stock
Assets
Other assets	$ 0	0
Fair value measurements measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Other
Assets
Other assets		$ 0

Financial Assets and Liabilit_4

Financial Assets and Liabilities - SBI Investment (Details)	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Transfers of financial instruments between levels	$ 0	$ 0
SBI
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount rate applied to cash flow forecasts to determine initial fair value of equity method investment.	15.00%
Market approach average price/earnings multiples of comparable companies to corroborate the income approach	14
Time period of projected income to determine fair value of equity method investment	5 years

Financial Assets and Liabilit_5

Financial Assets and Liabilities - Receivable from Bats (Details) $ in Millions	Mar. 31, 2015USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Payment receivable	$ 50
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Annual payment receivable	$ 6.6

Financial Assets and Liabilit_6

Financial Assets and Liabilities - Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 415,933	$ 532,887	$ 559,179	$ 181,415
Securities borrowed	1,305,789	1,471,172
Securities purchased under agreements to resell	10,014	0
Receivables from broker dealers and clearing organizations	1,115,764	972,018
Total assets	7,238,530	7,320,006
Liabilities
Short-term borrowings	14,567	27,883
Long-term borrowings	904,027	1,388,548
Securities loaned	800,145	754,687
Securities sold under agreements to repurchase	301,238	390,642
Payables to broker dealers and clearing organizations	952,343	716,205
Total liabilities	5,853,919	6,168,428
Fair value measurements not measured on a recurring basis | Carrying Value
Assets
Cash and cash equivalents	415,933	532,887
Securities borrowed	1,305,789	1,471,172
Securities purchased under agreements to resell	10,014
Receivables from broker dealers and clearing organizations	1,115,764	972,018
Total assets	2,847,500	2,976,077
Liabilities
Short-term borrowings	14,567	27,883
Long-term borrowings	904,027	1,388,548
Securities loaned	800,145	754,687
Securities sold under agreements to repurchase	301,238	390,642
Payables to broker dealers and clearing organizations	952,343	716,205
Total liabilities	2,972,320	3,277,965
Fair value measurements not measured on a recurring basis | Fair Value
Assets
Cash and cash equivalents	415,933	532,887
Securities borrowed	1,305,789	1,471,172
Securities purchased under agreements to resell	10,014
Receivables from broker dealers and clearing organizations	1,115,764	972,018
Total assets	2,847,500	2,976,077
Liabilities
Short-term borrowings	14,567	27,883
Long-term borrowings	950,685	1,465,489
Securities loaned	800,145	754,687
Securities sold under agreements to repurchase	301,238	390,642
Payables to broker dealers and clearing organizations	952,343	716,205
Total liabilities	3,018,978	3,354,906
Fair value measurements not measured on a recurring basis | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Cash and cash equivalents	415,933	532,887
Securities borrowed	0	0
Securities purchased under agreements to resell	0
Receivables from broker dealers and clearing organizations	225,274	36,513
Total assets	641,207	569,400
Liabilities
Short-term borrowings	0	0
Long-term borrowings	0	0
Securities loaned	0	0
Securities sold under agreements to repurchase	0	0
Payables to broker dealers and clearing organizations	277,486	2,925
Total liabilities	277,486	2,925
Fair value measurements not measured on a recurring basis | Fair Value | Significant Other Observable Inputs (Level 2)
Assets
Cash and cash equivalents	0	0
Securities borrowed	1,305,789	1,471,172
Securities purchased under agreements to resell	10,014
Receivables from broker dealers and clearing organizations	890,490	935,505
Total assets	2,206,293	2,406,677
Liabilities
Short-term borrowings	14,567	27,883
Long-term borrowings	950,685	1,465,489
Securities loaned	800,145	754,687
Securities sold under agreements to repurchase	301,238	390,642
Payables to broker dealers and clearing organizations	674,859	713,280
Total liabilities	2,741,494	3,351,981
Fair value measurements not measured on a recurring basis | Fair Value | Significant Unobservable Inputs (Level 3)
Assets
Cash and cash equivalents	0	0
Securities borrowed	0	0
Securities purchased under agreements to resell	0
Receivables from broker dealers and clearing organizations	0	0
Total assets	0	0
Liabilities
Short-term borrowings	0	0
Long-term borrowings	0	0
Securities loaned	0	0
Securities sold under agreements to repurchase	0	0
Payables to broker dealers and clearing organizations	0	0
Total liabilities	$ 0	$ 0

Financial Assets and Liabilit_7

Financial Assets and Liabilities - Level 3 financial instruments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 40,588	$ 36,031
Purchases	0	3,000
Total Realized and Unrealized Gains / (Losses)	(345)	1,232
Net Transfers into (out of) Level 3	0	0
Settlement	0	0
Ending Balance	40,243	40,263
Change in Net Unrealized Gains / (Losses) on Investments still held at end of period	(345)	1,232
Equity investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	40,588	36,031
Purchases	0	0
Total Realized and Unrealized Gains / (Losses)	(345)	1,232
Net Transfers into (out of) Level 3	0	0
Settlement	0	0
Ending Balance	40,243	37,263
Change in Net Unrealized Gains / (Losses) on Investments still held at end of period	$ (345)	1,232
Other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		0
Purchases		3,000
Total Realized and Unrealized Gains / (Losses)		0
Net Transfers into (out of) Level 3		0
Settlement		0
Ending Balance		3,000
Change in Net Unrealized Gains / (Losses) on Investments still held at end of period		$ 0

Financial Assets and Liabilit_8

Financial Assets and Liabilities - Netting of Certain Financial Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Securities borrowed
Gross Amounts of Recognized Assets	$ 1,305,789	$ 1,471,172
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	1,305,789	1,471,172
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(1,268,772)	(1,418,672)
Cash Collateral Received	(6,195)	(13,318)
Net Amount	30,822	39,182
Securities purchased under agreements to resell
Gross Amounts of Recognized Assets	10,014
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	10,014	0
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(9,993)
Cash Collateral Received	(21)
Net Amount	0
Total
Gross Amounts of Recognized Assets	3,246,054	3,523,704
Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition	(1,901,746)	(2,027,697)
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	1,344,308	1,496,007
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(1,279,564)	(1,418,717)
Cash Collateral Received	(6,216)	(13,318)
Net Amount	58,528	63,972
Currency forwards
Trading assets, at fair value:
Gross Amounts of Recognized Assets	1,929,452	2,045,487
Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition	(1,901,746)	(2,027,697)
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	27,706	17,790
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	0	0
Cash Collateral Received	0	0
Net Amount	27,706	17,790
Options
Trading assets, at fair value:
Gross Amounts of Recognized Assets	799	7,045
Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition	0	0
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	799	7,045
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(799)	(45)
Cash Collateral Received	0	0
Net Amount	$ 0	$ 7,000

Financial Assets and Liabilit_9

Financial Assets and Liabilities - Netting of Certain Financial Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Securities loaned
Gross Amounts of Recognized Liabilities	$ 800,145	$ 754,687
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	800,145	754,687
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(786,922)	(737,731)
Cash Collateral Pledged	(6,195)	(10,776)
Net Amount	7,028	6,180
Securities sold under agreements to repurchase
Gross Amounts of Recognized Liabilities	301,238	390,642
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	301,238	390,642
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(301,220)	(390,642)
Cash Collateral Pledged	(21)
Net Amount	(3)	0
Total
Gross Amounts of Recognized Liabilities	3,044,762	3,183,185
Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition	(1,942,686)	(2,024,991)
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	1,102,076	1,158,194
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(1,088,835)	(1,128,429)
Cash Collateral Pledged	(6,216)	(10,776)
Net Amount	7,025	18,989
Currency forwards
Trading liabilities, at fair value:
Gross Amounts of Recognized Liabilities	1,942,686	2,032,017
Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition	(1,942,686)	(2,024,991)
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	0	7,026
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments		0
Net Amount	0	7,026
Options
Trading liabilities, at fair value:
Gross Amounts of Recognized Liabilities	693	5,839
Gross Amounts Offset in the Condensed Consolidated Statement of Financial Condition		0
Net Amounts of Assets Presented in the Condensed Consolidated Statement of Financial Condition	693	5,839
Gross Amounts Not Offset In the Condensed Consolidated Statement of Financial Condition
Financial Instruments	(693)	(56)
Cash Collateral Pledged	0
Net Amount	$ 0	$ 5,783

Financial Assets and Liabili_10

Financial Assets and Liabilities - Gross Obligations For Securities Lending Transactions (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	$ 301,238	$ 390,642
Remaining contractual maturity for securities lending transactions	800,145	754,687
Overnight and Continuous
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	36,238	642
Remaining contractual maturity for securities lending transactions	800,145	754,687
Less than 30 days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	65,000	100,000
Remaining contractual maturity for securities lending transactions	0	0
30 - 60 days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	40,000	90,000
Remaining contractual maturity for securities lending transactions	0	0
61 - 90 Days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	160,000	200,000
Remaining contractual maturity for securities lending transactions	0	0
Equities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	265,000	390,000
Remaining contractual maturity for securities lending transactions	800,145	754,687
Equities | Overnight and Continuous
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	0	0
Remaining contractual maturity for securities lending transactions	800,145	754,687
Equities | Less than 30 days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	65,000	100,000
Remaining contractual maturity for securities lending transactions	0	0
Equities | 30 - 60 days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	40,000	90,000
Remaining contractual maturity for securities lending transactions	0	0
Equities | 61 - 90 Days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	160,000	200,000
Remaining contractual maturity for securities lending transactions	0	0
U.S. and Non-U.S. government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	36,238	642
U.S. and Non-U.S. government obligations | Overnight and Continuous
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	36,238	642
U.S. and Non-U.S. government obligations | Less than 30 days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	0	0
U.S. and Non-U.S. government obligations | 30 - 60 days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	0	0
U.S. and Non-U.S. government obligations | 61 - 90 Days
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining contractual maturity for repurchase agreements	$ 0	$ 0

Derivative Instruments - Fair V

Derivative Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Equities futures | Derivative instruments not designated as hedging instruments | Receivables from broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	$ 16,357	$ (505)
Derivatives Assets, Notional	3,398,419	1,985,770
Equities futures | Derivative instruments not designated as hedging instruments | Payables to broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	(1,687)	(575)
Derivatives Liabilities, Notional	127,500	142,658
Commodity futures | Derivative instruments not designated as hedging instruments | Receivables from broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	225,449	971
Derivatives Assets, Notional	12,830,011	21,231,001
Commodity futures | Derivative instruments not designated as hedging instruments | Payables to broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	(276,827)	(1,602)
Derivatives Liabilities, Notional	6,058,850	130,042
Currency futures | Derivative instruments not designated as hedging instruments | Receivables from broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	21,986	26,548
Derivatives Assets, Notional	2,672,739	3,994,412
Currency futures | Derivative instruments not designated as hedging instruments | Payables to broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	359	(13,947)
Derivatives Liabilities, Notional	2,566,892	7,756,958
Fixed income futures | Derivative instruments not designated as hedging instruments | Receivables from broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	0	73
Derivatives Assets, Notional	34,186	44,395
Fixed income futures | Derivative instruments not designated as hedging instruments | Payables to broker dealers and clearing organizations
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	1,039	(1)
Derivatives Liabilities, Notional	54,534	2,584
Options
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	799	7,045
Derivatives Liabilities, Fair Value	693	5,839
Options | Derivative instruments not designated as hedging instruments | Financial instruments owned
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	799	7,045
Derivatives Assets, Notional	139,046	682,369
Options | Derivative instruments not designated as hedging instruments | Financial instruments sold, not yet purchased
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	693	5,839
Derivatives Liabilities, Notional	140,079	681,147
Currency forwards
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	1,929,452	2,045,487
Derivatives Liabilities, Fair Value	1,942,686	2,032,017
Currency forwards | Derivative instruments not designated as hedging instruments | Financial instruments owned
Derivatives, Fair Value [Line Items]
Derivatives Assets, Fair Value	1,929,452	2,045,487
Derivatives Assets, Notional	138,790,533	124,000,221
Currency forwards | Derivative instruments not designated as hedging instruments | Financial instruments sold, not yet purchased
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	1,942,686	2,032,017
Derivatives Liabilities, Notional	138,797,150	123,993,234
Currency forwards | Derivative instruments designated as hedging instruments | Financial instruments sold, not yet purchased
Derivatives, Fair Value [Line Items]
Derivatives Liabilities, Fair Value	0	(514)
Derivatives Liabilities, Notional	$ 0	$ 16,115

Derivative Instruments - Gain F

Derivative Instruments - Gain From Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain impact that derivative instruments not designated as hedging instruments had on results of operations	$ 57,229	$ 65,292	$ (184,425)	$ 273,528
Derivative instruments designed as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Net gain from derivative instruments, which are recorded in accumulated other comprehensive income	699	19	855	19
Futures | Not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain impact that derivative instruments not designated as hedging instruments had on results of operations	103,950	35,097	(325,556)	249,274
Currency forwards | Not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain impact that derivative instruments not designated as hedging instruments had on results of operations	(47,882)	8,950	148,706	3,135
Options | Not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain impact that derivative instruments not designated as hedging instruments had on results of operations	1,161	21,120	(7,575)	21,119
Others | Not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain impact that derivative instruments not designated as hedging instruments had on results of operations	$ 0	$ 125	$ 0	$ 0

Revenues from Contracts with _3

Revenues from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	$ 40,252	$ 43,351	$ 140,661	$ 49,237
Total revenue	295,123	271,286	1,438,303	563,461
Receivables related to revenue from contracts with customers	1,700		1,700		$ 7,100
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	294,790		1,433,314
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	333		4,989
Commissions, net
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	39,919		135,672
Technology services
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	333		4,989
Other sources of revenue
Disaggregation of Revenue [Line Items]
Total revenue	254,871		1,297,642
Market Making
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	6,587		21,886
Total revenue	264,370	228,582	984,601	514,823
Market Making | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	264,370		984,601
Market Making | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	0		0
Market Making | Commissions, net
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	6,587		21,886
Market Making | Technology services
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	0		0
Market Making | Other sources of revenue
Disaggregation of Revenue [Line Items]
Total revenue	257,783		962,715
Execution Services
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	33,665		118,775
Total revenue	34,206	39,077	458,759	44,964
Execution Services | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	33,873		453,770
Execution Services | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	333		4,989
Execution Services | Commissions, net
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	33,332		113,786
Execution Services | Technology services
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	333		4,989
Execution Services | Other sources of revenue
Disaggregation of Revenue [Line Items]
Total revenue	541		339,984
Corporate
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	0		0
Total revenue	(3,453)	$ 3,627	(5,057)	$ 3,674
Corporate | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	(3,453)		(5,057)
Corporate | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	0		0
Corporate | Commissions, net
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	0		0
Corporate | Technology services
Disaggregation of Revenue [Line Items]
Revenues from contract with customers	0		0
Corporate | Other sources of revenue
Disaggregation of Revenue [Line Items]
Total revenue	$ (3,453)		$ (5,057)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes	$ 13,815	$ (6,505)	$ 75,330	$ (2,918)
Effective tax rate	46.90%	14.00%	13.80%	16.70%
Current income taxes receivable	$ 40,700		$ 40,700		$ 115,200
Current taxes payable	16,000		16,000		7,600
Deferred tax asset, alternative minimum tax	600		600		600
Operating loss carryforwards	231,800		231,800		231,800
Deferred tax asset, non-U.S. operating loss carryforward	$ 43,500		$ 43,500		43,500
Tax Cuts and Jobs Act, incomplete accounting change in rate, provisional income tax expense					$ 90,600

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Details) € in Millions, $ in Millions	Dec. 31, 2017USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2015USD ($)	Dec. 31, 2015EUR (€)
Commitments and Contingencies Disclosure [Abstract]
Amount of fine	$ 3.9	€ 3.3	$ 5.4	€ 5

Capital Structure - Additional

Capital Structure - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018classvoteshares	Sep. 30, 2017shares	Dec. 31, 2017shares
Class of Stock [Line Items]
Number of classes of common stock | class	4
Non-voting common interest units outstanding (in shares) | shares	9,012,000		12,301,067
Number of non-voting common interest units forfeited or repurchased (in shares) | shares	3,289,067	1,466,484
Class A common stock and Class C common stock
Class of Stock [Line Items]
Number of votes | vote	1
Class B common stock and Class D common stock
Class of Stock [Line Items]
Number of votes | vote	10

Capital Structure - Amended and

Capital Structure - Amended and Restated 2015 Management Incentive Plan (Details)	Apr. 21, 2015shares
2015 Management Incentive Plan | Class A
Class of Stock [Line Items]
Number of shares of stock authorized	16,000,000

Capital Structure - Acquisition

Capital Structure - Acquisition of KCG (Details) - USD ($) $ in Thousands	Aug. 10, 2017	Jul. 20, 2017	Sep. 30, 2018	Sep. 30, 2017
Class of Stock [Line Items]
Aggregate purchase price				$ 735,974
Class A
Class of Stock [Line Items]
Number of shares of stock issued			10,518,750
Class A | NIH Investment Agreement
Class of Stock [Line Items]
Number of shares of stock issued	338,124
Aggregate purchase price	$ 5,200
KCG | NIH Investment Agreement
Class of Stock [Line Items]
Number of shares of stock issued		39,725,979
Aggregate purchase price		$ 613,500
KCG | Class A | Aranda
Class of Stock [Line Items]
Number of shares of stock issued		6,346,155
Aggregate purchase price		$ 99,000
KCG | Class A | NIH Investment Agreement
Class of Stock [Line Items]
Number of shares of stock issued	338,124
Aggregate purchase price	$ 5,200
KCG | Class A | Temasek Investment
Class of Stock [Line Items]
Number of shares of stock issued	1,666,666
Aggregate purchase price	$ 26,000

Capital Structure - Share Repur

Capital Structure - Share Repurchase Program (Details) - USD ($) shares in Millions	Jul. 27, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Feb. 28, 2018
Class of Stock [Line Items]
Authorized repurchase amount	$ 100,000,000
Increase in authorized repurchase amount	$ 50,000,000
Value of shares repurchased			$ 58,218,000	$ 147,000
Class A
Class of Stock [Line Items]
Authorized repurchase amount					$ 50,000,000
Number of shares repurchased		2.4
Value of shares repurchased		$ 61,900,000
Remaining capacity for future purchases		$ 38,100,000	$ 38,100,000

Capital Structure - Secondary O

Capital Structure - Secondary Offerings (Details) - Class A - $ / shares	1 Months Ended	9 Months Ended
	May 31, 2018	Sep. 30, 2018
Class of Stock [Line Items]
Number of shares issued	17,250,000
Purchase price per share (in dollars per share)	$ 27.16
Offering price per share (in dollars per share)	$ 28
Number of shares of stock issued		10,518,750
Selling Stockholders
Class of Stock [Line Items]
Number of shares of stock issued		6,731,250
Number of shares issued upon exercise of stock options	2,081,250

Capital Structure - Employee Ex

Capital Structure - Employee Exchanges (Details)	9 Months Ended
	Sep. 30, 2018shares	Sep. 30, 2017shares
Virtu Financial
Class of Stock [Line Items]
Ownership interest (as a percent)	56.60%
VFH
Class of Stock [Line Items]
Common stock exchange ratio	1
VFH | Class A
Class of Stock [Line Items]
Issuance of common stock in connection with employee exchanges (in shares)	3,508,217	1,146,315

Share-based Compensation - Narr

Share-based Compensation - Narrative (Details) - USD ($) $ in Millions	Apr. 21, 2015	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense recognized		$ 2.5	$ 0	$ 7.1	$ 9.4
Granted (in shares)				594,536
Granted during period, value				$ 11.3
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized share-based compensation expense		25		$ 25		$ 14.3
Weighted average period for compensation expense expected to be recognized				1 year 1 month 6 days		1 year 6 months
RSUs | Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expense recognized		4.6	2.2	$ 13.1	7.1
2015 Management Incentive Plan | Non-qualified stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Expiration period	10 years
Expense recognized		1.4	$ 1.4	4.2	$ 4.2
Unrecognized share-based compensation expense		$ 3.1		$ 3.1		$ 7.5
Weighted average period for compensation expense expected to be recognized				7 months 6 days		1 year 3 months 18 days
2015 Management Incentive Plan | RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years

Share-based Compensation - Summ

Share-based Compensation - Summary of Activity in Options (Details) - 2015 Management Incentive Plan - Non-qualified stock options - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Outstanding (in shares)	7,783,000	8,234,000	8,234,000
Forfeited or expired (in shares)	(83,750)	(401,000)
Exercised (in shares)	(4,086,558)
Outstanding (in shares)	3,612,692	7,833,000	7,783,000	8,234,000
Weighted Average Exercise Price Per Share
Outstanding (in dollars per share)	$ 19	$ 19	$ 19
Exercised (in dollars per share)	19
Outstanding (in dollars per share)	$ 19	$ 19	$ 19	$ 19
Weighted Average Remaining Contractual Life
Weighted Average Remaining Life	6 years 6 months 18 days	7 years 6 months 18 days	7 years 3 months 15 days	8 years 3 months 15 days
Options Exercisable, Number of Options (in shares)	1,741,942	3,916,500	3,891,500	2,058,500
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 19	$ 19	$ 19	$ 19

Share-based Compensation - Su_2

Share-based Compensation - Summary of Activity in RSUs (Details) - 2015 Management Incentive Plan - RSUs - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Number of Shares
Outstanding (in shares)	853,047	1,573,441
Granted (in shares)	1,265,899	34,825
Forfeited (in shares)	(127,493)	(212,729)
Vested (in shares)	(83,942)	(58,536)
Outstanding (in shares)	1,907,511	1,337,001
Weighted Average Fair Value
Outstanding (in dollars per share)	$ 17.94	$ 18.28
Granted (in dollars per share)	20.89	17.95
Forfeited (in dollars per share)	18.30	18.46
Vested (in dollars per share)	18.25	19.22
Outstanding (in dollars per share)	$ 19.86	$ 18.21

Regulatory Requirement - Narrat

Regulatory Requirement - Narrative (Details)	9 Months Ended
	Sep. 30, 2018USD ($)broker_dealertrading_unit	Dec. 31, 2017USD ($)	Nov. 03, 2017broker_dealer
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Regulatory capital	$ 1,000,000
Number of broker-dealer subsidiaries | broker_dealer	3		3
Virtu Financial Capital Markets LLC
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Regulatory capital	$ 9,020,000	$ 8,308,000
Minimum capital required to be maintained in connection with the operation of the Company's DMM business	3,100,000	$ 4,100,000
Required amount under exchange rules	$ 1,000,000
Required amount under exchange rules as percentage of market value	15.00%
Number of trading units whose market value is considered to calculate required net capital under exchange act | trading_unit	60

Regulatory Requirement - Regula

Regulatory Requirement - Regulatory Capital and Capital Requirements (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Entity Information [Line Items]
Regulatory Capital	$ 1,000,000
Virtu Americas LLC
Entity Information [Line Items]
Regulatory Capital	337,534,000	$ 379,875,000
Regulatory Capital Requirement	4,086,000	1,000,000
Excess Regulatory Capital	333,448,000	378,875,000
Virtu Financial BD LLC
Entity Information [Line Items]
Regulatory Capital	82,546,000	40,683,000
Regulatory Capital Requirement	1,000,000	1,000,000
Excess Regulatory Capital	81,546,000	39,683,000
Virtu Financial Capital Markets LLC
Entity Information [Line Items]
Regulatory Capital	9,020,000	8,308,000
Regulatory Capital Requirement	1,000,000	5,114,000
Excess Regulatory Capital	$ 8,020,000	$ 3,194,000

Geographic Information and Bu_3

Geographic Information and Business Segments - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues from External Customers [Line Items]
Total revenue	$ 295,123	$ 271,286	$ 1,438,303	$ 563,461
United States
Revenues from External Customers [Line Items]
Total revenue	245,631	218,042	1,266,047	399,361
Ireland
Revenues from External Customers [Line Items]
Total revenue	21,938	17,874	60,563	79,129
United Kingdom
Revenues from External Customers [Line Items]
Total revenue	479	10,485	15,324	10,485
Singapore
Revenues from External Customers [Line Items]
Total revenue	26,921	22,601	95,757	72,210
Others
Revenues from External Customers [Line Items]
Total revenue	$ 154	$ 2,284	$ 612	$ 2,276

Geographic Information and Bu_4

Geographic Information and Business Segments - Segments (Details) $ in Thousands	Jul. 19, 2017businesssegment	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)segment	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of businesses managed and operated | business	1
Number of reportable segments | segment	1
Number of operating segments | segment	1		3
Total revenue		$ 295,123	$ 271,286	$ 1,438,303	$ 563,461
Income (loss) before income taxes and noncontrolling interest		29,425	(46,495)	547,585	(17,421)
Market Making
Segment Reporting Information [Line Items]
Total revenue		264,370	228,582	984,601	514,823
Income (loss) before income taxes and noncontrolling interest		39,744	(19,322)	262,910	17,241
Execution Services
Segment Reporting Information [Line Items]
Total revenue		34,206	39,077	458,759	44,964
Income (loss) before income taxes and noncontrolling interest		129	(6,017)	331,703	(4,913)
Corporate
Segment Reporting Information [Line Items]
Total revenue		(3,453)	3,627	(5,057)	3,674
Income (loss) before income taxes and noncontrolling interest		$ (10,448)	$ (21,156)	$ (47,028)	$ (29,749)

Related Party Transactions (Det

Related Party Transactions (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)joint_venture	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)joint_venture	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Related Party Transaction [Line Items]
Payable to affiliates	$ 3,700		$ 3,700		$ 100
Securities loaned	800,145		800,145		754,687
Securities borrowed	1,305,789		1,305,789		1,471,172
SBI
Related Party Transaction [Line Items]
Payments to related party	1,500	$ 1,400	6,200	$ 4,100
ICBC
Related Party Transaction [Line Items]
Securities loaned	400		400		1,100
Securities borrowed					$ 23,100
Level 3
Related Party Transaction [Line Items]
Payments for purchases	400	500	1,900	1,600
Dell
Related Party Transaction [Line Items]
Payments for purchases		500	800	1,900
MarkIt
Related Party Transaction [Line Items]
Payments for purchases			400
Two microwave communication network JVs
Related Party Transaction [Line Items]
Payments to related party	$ 3,000	$ 200	$ 13,100	$ 400
Number of microwave communication network JVs the Company makes payments to | joint_venture	2		2

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event	Nov. 06, 2018USD ($)$ / shares
ITG
Subsequent Events [Line Items]
Business acquisition, cash price (in dollars per share) | $ / shares	$ 30.30
Total purchase price | $	$ 1,000,000,000
ITG | Jefferies Finance LLC and Royal Bank of Canada
Subsequent Events [Line Items]
Face amount | $	$ 1,500,000,000
Class A
Subsequent Events [Line Items]
Dividends declared (in dollars per share) | $ / shares	$ 0.24