Compensation - Summary of the BGC Holdings and Newmark Holdings LPUs held by BGC Employees (Detail) - LPUs - shares	Jun. 30, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance outstanding (in shares)	105,708,000	112,115,000
Newmark
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance outstanding (in shares)	10,355,000	11,051,000
Regular Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance outstanding (in shares)	74,469,000
Regular Units | Newmark
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance outstanding (in shares)	7,888,000
Preferred Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance outstanding (in shares)	31,239,000
Preferred Units | Newmark
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance outstanding (in shares)	2,467,000