Compensation - Summary of Compensation Expense Related to Amortization of LPUs Held by BGC Employees (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	$ 18,961	$ 19,862	$ 53,585	$ 53,696
Stated vesting schedule
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	18,843	19,880	53,421	53,655
Post-termination payout
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	$ 118	$ (18)	$ 164	$ 41