Segment, Geographic and Product Information - Product Information Regarding Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total revenues	$ 1,795,302	$ 2,015,364	$ 2,056,761
Total brokerage revenues
Segment Reporting Information [Line Items]
Total revenues	1,646,801	1,869,661	1,919,301
Rates
Segment Reporting Information [Line Items]
Total revenues	549,503	558,507	544,094
FX
Segment Reporting Information [Line Items]
Total revenues	299,721	301,328	315,253
Energy and commodities
Segment Reporting Information [Line Items]
Total revenues	291,665	296,458	292,641
Credit
Segment Reporting Information [Line Items]
Total revenues	271,419	287,608	329,904
Equities
Segment Reporting Information [Line Items]
Total revenues	234,493	247,673	254,702
Insurance1
Segment Reporting Information [Line Items]
Total revenues	0	178,087	182,707
All other revenues
Segment Reporting Information [Line Items]
Total revenues	$ 148,501	$ 145,703	$ 137,460