Acquisitions - Calculation of the Purchase Price Consideration Transferred (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
	Apr. 01, 2025	Jun. 30, 2025	Dec. 31, 2024
Business Combination [Line Items]
Total purchase price consideration transferred		$ 309,300	$ 87,300
OTC Global
Business Combination [Line Items]
Cash	$ 318,859
Fair value of Restricted Shares of BGC Class A common stock (268,257 shares)	2,507
Other	3,634
Less: compensation arrangements with required future service periods	(15,717)
Total purchase price consideration transferred	$ 309,283
OTC Global | Class A Common Stock
Business Combination [Line Items]
Issuance of Restricted Shares of BGC Class A common stock in acquisitions (in shares)	268,257