Related Party Transactions - Service Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Related Party Transaction [Line Items]
Total revenues	$ 784,004	$ 550,761	$ 1,448,244	$ 1,129,375
Tower Bridge International Services LP | BGC Partners, Inc.
Related Party Transaction [Line Items]
Company ownership of Tower Bridge (as a percent)			52.00%
Tower Bridge International Services LP | Cantor
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners (as a percent)	48.00%		48.00%
Related Party
Related Party Transaction [Line Items]
Mark-up cost of services (as a percent)			7.50%
Share of net profit (loss) from noncontrolling interest	$ 1,100	500	$ 1,600	700
Compensation to leased employees	24,900	17,700	52,900	37,100
Related Party | Service Agreement with Cantor
Related Party Transaction [Line Items]
Total revenues	5,200	4,600	9,700	9,100
Service charges	$ 35,300	$ 25,700	$ 71,700	$ 52,300