Capital Structure (Details) $ / shares in Units, $ in Thousands					1 Months Ended					9 Months Ended	12 Months Ended
	Aug. 10, 2017 USD ($) shares	Jul. 20, 2017 USD ($) $ / shares shares	Apr. 21, 2015 $ / shares shares	Apr. 15, 2015 shares	Nov. 30, 2017 shares	Aug. 31, 2017 shares	May 31, 2017 shares	Feb. 28, 2017 shares	Sep. 30, 2016 $ / shares shares	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) Vote item $ / shares	Dec. 31, 2016 $ / shares	Jul. 27, 2016
Aggregate purchase price | $										$ 327,366	$ 735,974
Ownership interest (as a percent)													29.40%
Number of classes of common stock | item											4
Virtu Financial
Ownership interest (as a percent)											48.30%
VFH
Issuance of common stock in connection with employee exchanges (in shares) | shares					209,448	155,009	307,544	683,762
Common stock exchange ratio								1
Class A
Number of shares of stock issued | shares			19,012,112	16,532,272
Common stock, par value (in dollars per share)			$ 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) | 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)			$ 19.00
Common stock offered for sale (in shares) | shares									1,103,668
Price of stock (in dollars per share)									$ 15.75
Commission deducted from the price at which shares were offered to the public (in dollars per share)									$ 0.10
Class A | 2015 Management Incentive Plan
Number of shares of stock authorized | shares			16,000,000
Class A | VFH
Common stock, par value (in dollars per share)											0.00001
Class B
Common stock, par value (in dollars per share)											0.00001	0.00001
Class B | VFH
Common stock, par value (in dollars per share)											0.00001
Class C
Common stock, par value (in dollars per share)											0.00001	0.00001
Class C | VFH
Common stock, par value (in dollars per share)											0.00001
Class D
Common stock, par value (in dollars per share)											0.00001	$ 0.00001
Class D | VFH
Common stock, par value (in dollars per share)											$ 0.00001
Class A common stock and Class C common stock
Number of votes | Vote											1
Class B common stock and Class D common stock
Number of votes | Vote											10
Temasek Investment
Other offering costs | $	$ 7,800
NIH Investment Agreement | Class A
Number of shares of stock issued | shares	338,124
Aggregate purchase price | $	$ 5,200
KCG
Common stock, par value (in dollars per share)		$ 0.01
KCG | Aranda | Class A
Number of shares of stock issued | shares		6,346,155
Aggregate purchase price | $		$ 99,000
KCG | Temasek Investment | Class A
Number of shares of stock issued | shares	1,666,666
Aggregate purchase price | $	$ 26,000
KCG | NIH Investment Agreement
Number of shares of stock issued | shares		39,725,979
Aggregate purchase price | $		$ 613,500
KCG | NIH Investment Agreement | Class A
Number of shares of stock issued | shares	338,124
Aggregate purchase price | $	$ 5,200