Revenues from Contracts with Customers - Summary of Revenues from Contracts with Customers and Other Sources of Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues From Contracts With Customers [Line Items]
Revenues from contracts with customers	$ 1,607,379	$ 1,406,692	$ 1,663,537
Principal transactions	368,100	365,507	327,761
Interest and dividend income	45,422	21,007	21,977
Other revenues	4,500	2,096	2,089
Total revenues	2,025,401	1,795,302	2,015,364
Commissions
Revenues From Contracts With Customers [Line Items]
Revenues from contracts with customers	1,464,524	1,281,294	1,541,900
Data, network, and post-trade
Revenues From Contracts With Customers [Line Items]
Revenues from contracts with customers	111,470	96,389	89,963
Fees from related parties
Revenues From Contracts With Customers [Line Items]
Revenues from contracts with customers	15,968	14,734	14,856
Other revenues
Revenues From Contracts With Customers [Line Items]
Revenues from contracts with customers	15,417	14,275	16,818
Total revenues	$ 192,777	$ 148,501	$ 145,703