Investments - Equity Method Investments and Investments Carried Under Measurement Alternative (Detail) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 43,381	$ 39,075
Investments carried under measurement alternative	192	192
Total equity method and investments carried under measurement alternative	$ 43,573	39,267
Advanced Markets Holdings
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage amount (as a percent)	25.00%
Equity method investments	$ 3,781	3,772
China Credit BGC Money Broking Company Limited
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage amount (as a percent)	33.00%
Equity method investments	$ 27,283	23,242
Freedom International Brokerage
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage amount (as a percent)	45.00%
Equity method investments	$ 8,827	9,637
Other
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 3,490	$ 2,424