Compensation - Compensation Expense Related to Issuance of BGC or Newmark Class A Common Stock and Grants of Exchangeability on BGC Holdings and Newmark Holdings LPUs held by BGC Employees (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
LPUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock and grants of exchangeability	$ 101,938	$ 20,460	$ 153,904	$ 50,595