Compensation - Units Redeemed in Connection with Issuance of Class A Common Stock (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	11,360,611	9,376,796	50,181,129
BGC Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	127,960	142,194	13,803,080
Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	11,232,651	9,234,602	36,378,049