Compensation - Units Redeemed in Connection with Issuance of Class A Common Stock (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	567,155	686,544
BGC Units
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	34,557	46,605
Newmark Units
Share-based Compensation Arrangement by Share-based Payment Award
Number of units redeemed (in shares)	532,598	639,939