Commitments, Contingencies and Guarantees	12 Months Ended
Commitments, Contingencies and Guarantees	Dec. 31, 2020
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 judgments, settlements, disgorgements, restitution, penalties, injunctions, 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 and other insurance coverage for potential claims, including securities actions, against the Company and its respective directors and officers. On January 29, 2019, the Company was named as a defendant in Ford v. ProShares Trust II, et al., No. 19-cv-886. The complaint was filed in federal district court in New York on behalf of a putative class, and asserts claims against the Company and numerous other financial institutions under Section 11 of the Securities Act of 1933 in connection with a ProShares inverse-volatility ETF. Additionally, on February 27, 2019, and March 1, 2019, the Company was named as a defendant in Bittner v. ProShares Trust II, et al., No. 19-cv-1840, and Mareno v. ProShares Trust II, et al., No. 19-cv-1955, respectively. The complaints were filed in federal district court in New York on behalf of putative classes, and asserted substantially similar claims against the Company and other financial institutions. On April 29, 2019, these three actions were consolidated in federal district court in New York as In re ProShares Trust II Securities Litigation, No. 19-cv-886-DLC. A consolidated amended complaint, which did not specify the amount of alleged damages, was filed in the consolidated action on June 21, 2019. Defendants moved to dismiss the consolidated amended complaint on August 2, 2019. In response, plaintiffs filed a consolidated second amended complaint on September 6, 2019, which also did not specify the amount of alleged damages. Defendants moved to dismiss the consolidated second amended complaint on September 27, 2019. The defendants’ motion to dismiss was granted on January 3, 2020, and plaintiffs subsequently filed a Notice of Appeal of the district court's ruling on the motion to dismiss on January 31, 2020 and an opening brief on May 14, 2020. The defendants' response brief was filed August 13, 2020 and the plaintiffs' reply was filed September 17, 2020. The Company believes that the claims are without merit and is defending itself vigorously. On November 30, 2020, the Company was named as a defendant in In re United States Oil Fund, LP Securities Litigation, No. 20-cv-4740. The consolidated amended complaint was filed in federal district court in New York on behalf of a putative class, and asserts claims against the Company and numerous other financial institutions under Section 11 of the Securities Act of 1933 in connection with trading in United States Oil Fund, LP, a crude oil ETF. The complaint also names the ETF, its sponsor, and related individuals as defendants. The complaint did not specify the amount of alleged damages. Defendants moved to dismiss the consolidated amended complaint on January 29, 2021. The Company believes that the claims are without merit and is defending itself 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 and low-priced 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, the retail trading environment in the U.S. and relationships between retail broker-dealers and market making firms, high frequency trading, best execution, internalization, alternative trading system (“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 other payment and rebate structures and arrangements. From time to time, the Company is the subject of requests for information and documents from the SEC, the Financial Industry Regulatory Authority, states attorney generals, and other regulators and governmental authorities. It is the Company's practice to cooperate and comply with the requests for information and documents. The Company is currently the subject of various regulatory reviews and investigations by state, federal and foreign regulators and SROs, including the SEC and the Financial Industry Regulatory Authority. In some instances, these matters may result in a disciplinary action and/or a civil or administrative action. For example, in December 2015, 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) and in 2018 was further reduced to €3.0 million (approximately $3.4 million). The Company has fully reserved for the monetary penalty as of December 31, 2020. 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, including indemnification obligations in connection with the Acquisition of KCG and the ITG Acquisition. 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 enters into contracts that contain a variety of representations and warranties and general indemnifications. The Company has also 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.