Compensation - Limited Partnership Units with a Post-Termination Payout (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
BGC Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award
Notional value	$ 158,755	$ 158,594
Estimated fair value of the post-termination payout	$ 57,277	$ 54,950
NEWMARK Group Inc
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding limited partnership units (in shares)	16,756,564	16,704,405
Outstanding limited partnership units - unvested (in dollars per share)	402,111	4,856,908