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
	Mar. 31, 2025	Mar. 31, 2024
LPUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock and grants of exchangeability	$ 26,641	$ 33,832