Compensation - Units Redeemed in Connection with Issuance of Class A Common Stock (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	2,350,268	3,168,080	7,333,712	6,985,253
BGC Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	0	11,404	0	127,960
Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	2,350,268	3,156,676	7,333,712	6,857,293