Capital Structure - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021 vote class shares	Sep. 30, 2020 shares	Dec. 31, 2020 shares
Class of Stock [Line Items]
Number of classes of common stock | class	4
Non-voting common interest units outstanding (in shares) | shares	4,795,839		5,259,713
Number of non-voting common interest units forfeited or repurchased (in shares) | shares	463,874	2,420,239
Virtu Financial
Class of Stock [Line Items]
Ownership interest	62.60%
Class A common stock and Class C common stock
Class of Stock [Line Items]
Number of votes | vote	1
Class B common stock and Class D common stock
Class of Stock [Line Items]
Number of votes | vote	10
Class C common stock and class D common stock | Founder
Class of Stock [Line Items]
Ownership interest	83.00%