Tax Receivable Agreements (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Apr. 15, 2015	Feb. 28, 2017	Dec. 31, 2015	Sep. 30, 2017	Dec. 31, 2016
Payment on applicable cash tax savings (as a percent)	85.00%
First payment due after filing of company's tax return			120 days
First payment made		$ 7,000
Deferred tax assets related to exchange of units	$ 218,400
Payments to certain Virtu Members	238,600
Minimum tax receivable agreement obligation over the agreed period	400
Maximum tax receivable agreement obligation over the agreed period	$ 21,400
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.	$ 20,200
Deferred tax asset recorded in connection with a stock offering		9,500
Amount of payment liability pursuant to tax receivable agreements		8,200
Increase in additional paid-in capital related to tax receivable agreements		$ 1,300
Deferred tax assets				$ 191,300	$ 185,600
Tax receivable agreement obligations				232,552	$ 231,404
KCG
Deferred tax assets				$ 22,100