Investments - Equity Method Investments and Investments Carried Under Measurement Alternative (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 38,122	$ 38,383
Investments carried under measurement alternative	192	192
Total equity method and investments carried under measurement alternative	$ 38,314	38,575
Advanced Markets Holdings
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage amount	25.00%
Equity method investments	$ 4,481	5,090
China Credit BGC Money Broking Company Limited
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage amount	33.00%
Equity method investments	$ 21,277	21,104
Freedom International Brokerage
Schedule of Equity Method Investments [Line Items]
Investment ownership percentage amount	45.00%
Equity method investments	$ 9,507	9,659
Other
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 2,857	$ 2,530