Capital Structure (Details) $ / shares in Units, $ in Millions					1 Months Ended				9 Months Ended
	Aug. 10, 2017 USD ($) shares	Jul. 20, 2017 USD ($) $ / shares shares	Apr. 21, 2015 $ / shares shares	Apr. 15, 2015 shares	Aug. 31, 2017 shares	May 31, 2017 shares	Feb. 28, 2017 shares	Sep. 30, 2016 $ / shares shares	Sep. 30, 2017 Vote item $ / shares	Dec. 31, 2016 $ / shares	Nov. 30, 2015 item $ / shares shares
Aggregate purchase price | $		$ 613.5
Number of classes of common stock | item									4
Number of votes | Vote									10
Common stock offered for sale (in shares)											397,534
Commission deducted from the price at which shares were offered to the public (in dollars per share) | $ / shares								$ 0.10
2015 Management Incentive Plan
Number of shares of stock authorized			16,000,000
Virtu Financial
Ownership interest (as a percent)									48.00%
VFH
Issuance of common stock in connection with employee exchanges (in shares)					155,009	307,544	683,762
Common stock exchange ratio							1
Silver Lake Post-IPO
Common stock offered for sale (in shares)											6,075,837
Class A
Number of shares of stock issued			19,012,112	16,532,272
Common stock, par value (in dollars per share) | $ / shares			$ 0.00001						$ 0.00001	$ 0.00001
Common stock sold in connection with full exercise of the option to purchase additional shares granted to underwriters (in shares)			2,479,840
Common stock sold in connection with full exercise of the option to purchase additional shares granted to underwriters, at a price to public (in dollars per share) | $ / shares			$ 19.00
Common stock offered for sale (in shares)								1,103,668
Price of stock (in dollars per share) | $ / shares								$ 15.75
Class A | Virtu Financial Inc And Silver Lake Partners
Common stock offered for sale (in shares)											6,473,371
Price of stock (in dollars per share) | $ / shares											$ 22.15
Class B
Common stock, par value (in dollars per share) | $ / shares									0.00001	0.00001
Class C
Common stock, par value (in dollars per share) | $ / shares									0.00001	0.00001
Class D
Common stock, par value (in dollars per share) | $ / shares									$ 0.00001	$ 0.00001
Class A common stock and Class C common stock
Number of votes | Vote									1
Number Of Non Executive Employees | item											1
Temasek Investment
Other offering costs | $	$ 7.8
Temasek Investment | Class A
Number of shares of stock issued	1,666,666
Aggregate purchase price | $	$ 26.0
NIH Investment Agreement
Number of shares of stock issued	338,124
Aggregate purchase price | $	$ 5.2
KCG
Common stock, par value (in dollars per share) | $ / shares		$ 0.01
KCG | Aranda | Class A
Number of shares of stock issued		6,346,155
Aggregate purchase price | $		$ 99.0
KCG | Temasek Investment | Class A
Number of shares of stock issued	1,666,666
Aggregate purchase price | $	$ 26.0
KCG | NIH Investment Agreement
Number of shares of stock issued		39,725,979
Aggregate purchase price | $		$ 613.5
KCG | NIH Investment Agreement | Class A
Number of shares of stock issued	338,124	39,725,979
Aggregate purchase price | $	$ 5.2