Compensation - Summary of Compensation Expense Related to Amortization of LPUs Held by BGC Employees (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	$ 21,431	$ 19,023
Stated vesting schedule
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	21,407	18,969
Post-termination payout
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	$ 24	$ 54