Compensation - Summary of Compensation Expense Related to Amortization of LPUs Held by BGC Employees (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	$ 40,878	$ 73,734	$ 78,596
Stated vesting schedule
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	40,848	74,561	78,535
Post-termination payout
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LPU amortization	$ 30	$ (827)	$ 61