Compensation - Activity Associated with Limited Partnership Units Awarded to BGC Employees (Detail) - LPUs - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units, redeemed (in shares)	11,053,000	6,051,000
BGC Holdings LPUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units, redeemed (in shares)	10,975,000	5,787,000
Newmark Holdings LPUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units, redeemed (in shares)	78,000	264,000