Equity-Based and Other Deferred Compensation - Unvested Units After Expected Forfeitures which are Expected to Vest (Details)	6 Months Ended
	Jun. 30, 2019 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units expected to vest	12,688,494
Weighted-average service period of unit expected to vest (in years)	9 months 18 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units expected to vest	4,468,637
Weighted-average service period of unit expected to vest (in years)	1 year 6 months
Restricted Share Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units expected to vest	7,447
Weighted-average service period of unit expected to vest (in years)	2 years 3 months 18 days
PJT Partners Holdings LP | Partnership Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units expected to vest	8,212,410
Weighted-average service period of unit expected to vest (in years)	4 months 24 days