Parent Company - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	4 Months Ended	9 Months Ended	12 Months Ended
	Apr. 15, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income (loss)	$ 83,147	$ 114,343	$ 18,898	$ 158,340	$ 197,490
Adjustments to reconcile net income to net cash provided by operating activities:
Tax receivable agreement obligation reduction			(86,599)
Deferred taxes			102,973	13,313	3,985
Other			(4,577)	(1,070)	219
Net cash provided by operating activities			290,574	239,599	260,280
Cash flows from investing activities
Acquisition of KCG Holdings, net of cash acquired, described in Note 3			(799,632)
Cash flows used in investing activities			(838,016)	(59,017)	(24,299)
Cash flows from financing activities
Distribution to members					(130,000)
Distribution from Virtu Financial to non-controlling interest			(89,563)	(162,969)	(81,377)
Dividends			(63,814)	(37,759)	(17,362)
Proceeds from issuance			735,974		327,366
Purchase of treasury stock			(2,683)	(4,539)	(3,819)
Tax receivable agreement obligations			(7,045)
Repurchase of Virtu Financial Units and corresponding number of Class A and C Common Stock					(277,153)
Issuance of common stock, net of offering costs				16,677	7,782
Repurchase of Virtu Financial Units and corresponding number of Class A and C common stock in connection with secondary offering				(17,383)	(8,805)
Net cash provided by (used in) financing activities			889,797	(161,237)	(144,355)
Supplementary disclosure of cash flow information
Tax receivable agreement described in Note 4			(1,534)	(545)	21,854
Discount on issuance of senior secured credit facility			1,438	1,350
Taxes paid			5,976	16,175	12,875
VFH
Cash flows from operating activities
Net income (loss)			2,939	32,980	104,034
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income of subsidiary, net of tax			(513,601)	157,975	(18,237)
Tax receivable agreement obligation reduction			(86,599)
Deferred taxes			102,973	13,197	3,392
Other			(8,500)
Changes in operating assets and liabilities			(8,832)	(4,012)	5,900
Net cash provided by operating activities			(511,620)	200,140	95,089
Cash flows from investing activities
Acquisition of KCG Holdings, net of cash acquired, described in Note 3			(23,908)
Investment in subsidiaries, equity basis			16,846	24,893	64,624
Cash flows used in investing activities			(7,062)	24,893	64,624
Cash flows from financing activities
Distribution to members					(130,000)
Distribution from Virtu Financial to non-controlling interest		(89,563)		(162,969)	(81,377)
Proceeds from issuance			735,974		327,366
Purchase of treasury stock			(2,683)	(4,539)	(3,819)
Tax receivable agreement obligations			(7,045)
Repurchase of Virtu Financial Units and corresponding number of Class A and C Common Stock					(277,153)
Issuance of common stock, net of offering costs				16,677	7,782
Repurchase of Virtu Financial Units and corresponding number of Class A and C common stock in connection with secondary offering				(17,383)	(8,805)
Net cash provided by (used in) financing activities			561,726	(208,071)	(185,465)
Net increase (decrease) in cash			43,044	16,962	(25,752)
Cash, beginning of period	$ 25,939		17,149	187	25,939
Cash, end of period		$ 187	60,193	17,149	187
Supplementary disclosure of cash flow information
Tax receivable agreement described in Note 4			1,534		(21,854)
Discount on issuance of senior secured credit facility				1,350
Taxes paid			133	8,813	5,615
Class A | VFH
Cash flows from financing activities
Dividends			(63,814)	(37,759)	(17,362)
Class C
Cash flows from financing activities
Purchase of treasury stock				(98)
Class C | VFH
Cash flows from financing activities
Repurchase of Virtu Financial Units and corresponding number of Class A and C Common Stock				(98)
Class A-2 | VFH
Cash flows from financing activities
Repurchase of Class A-2 interests			$ (11,143)	$ (2,000)	$ (2,097)