XML 42 R96.htm IDEA: XBRL DOCUMENT v3.20.1
Compensation - Summary of the BGC Holdings and Newmark Holdings LPUs held by BGC Employees (Detail) - LPUs [Member] - shares
Mar. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Units, Balance outstanding 112,577,000 102,407,000
Newmark [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Units, Balance outstanding 14,576,000 14,607,000
Regular Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Units, Balance outstanding 78,054,000  
Regular Units [Member] | Newmark [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Units, Balance outstanding 10,405,000  
Preferred Units [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Units, Balance outstanding 34,523,000  
Preferred Units [Member] | Newmark [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Units, Balance outstanding 4,171,000