Related Party Transactions - BGC Sublease from Newmark (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Nov. 30, 2018 shares	May 31, 2020 USD ($) ft²	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	May 31, 2021 USD ($)
Related Party Transaction [Line Items]
Total revenues			$ 2,025,401	$ 1,795,302	$ 2,015,364
LPUs | Newmark
Related Party Transaction [Line Items]
Aggregate exchangeable limited partnership units purchased (in shares) | shares	1,500,000
Class A Common Stock
Related Party Transaction [Line Items]
Common stock, shares issued (in shares) | shares			403,574,835	471,933,933
Class B Common Stock
Related Party Transaction [Line Items]
Common stock, shares issued (in shares) | shares			109,452,953	45,884,380
Newmark | Class A Common Stock
Related Party Transaction [Line Items]
Limited partnership interests exchange ratio			92.31%
Related Party | Class B Common Stock | Newmark
Related Party Transaction [Line Items]
Common stock, shares issued (in shares) | shares	400,000
Related Party
Related Party Transaction [Line Items]
Lessee operating lease sublease term		1 year
Area of sublease | ft²		21,000
Operating lease cost		$ 1,100
Monthly rent expense						$ 15
Rent payment under lease term					500
Total revenues			$ 16,000	$ 14,700	14,900
Related Party | Lucera
Related Party Transaction [Line Items]
Total revenues			$ 0	$ 0	$ 200