Compensation - Limited Partnership Units with a Post-Termination Payout (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024
BGC Holdings, L.P.
Share-based Compensation Arrangement by Share-based Payment Award
Notional Value	$ 157,172	$ 161,861
Estimated fair value of the post-termination payout	$ 57,883	$ 56,210
Newmark Holdings Units
Share-based Compensation Arrangement by Share-based Payment Award
Outstanding limited partnership units (in shares)	15,949,192	17,249,585
Outstanding limited partnership units - unvested (in dollars per share)	3,984,578	5,570,815