Segment, Geographic and Product Information - Product Information Regarding Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Total revenues	$ 550,761	$ 493,080	$ 1,129,375	$ 1,025,947
Rates
Segment Reporting Information [Line Items]
Total revenues	166,044	144,209	341,129	308,946
ECS
Segment Reporting Information [Line Items]
Total revenues	117,743	98,688	172,969	157,685
FX
Segment Reporting Information [Line Items]
Total revenues	88,946	77,527	156,973	155,355
Credit
Segment Reporting Information [Line Items]
Total revenues	69,381	65,806	236,207	188,347
Equities
Segment Reporting Information [Line Items]
Total revenues	51,406	57,373	114,263	125,487
Total brokerage revenues
Segment Reporting Information [Line Items]
Total revenues	493,520	443,603	1,021,541	935,820
All other revenues
Segment Reporting Information [Line Items]
Total revenues	$ 57,241	$ 49,477	$ 107,834	$ 90,127