XML 136 R124.htm IDEA: XBRL DOCUMENT v3.19.2
Compensation - Summary of Activity of Number of Share Equivalent Limited Partnership Units and Post IPO Grants (Detail) - Newmark Holdings, L.P. [Member] - Share Equivalent Limited Partnership Units [Member] - shares
6 Months Ended 12 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of Units, Balance outstanding at beginning of period 44,733,487 29,413,143 29,413,143
Number of Units, Granted 10,746,929   19,141,943
Number of Units, Redeemed/exchanged units (880,960)   (3,793,351)
Number of Units, Forfeited units     (28,248)
Number of Units, Forfeited units/Other units 4,846,170    
Number of Units, Balance outstanding at end of period 59,445,626 44,700,000 44,733,487