Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.8.0.1
Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended
Aug. 31, 2017
Jun. 30, 2017
May 31, 2017
Apr. 30, 2017
Mar. 31, 2017
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Class Of Stock [Line Items]                  
Partnership distributions, amount           $ 1,359 $ 1,345 $ 6,001 $ 5,760
Distributions of partner incentive allocations of net income               $ 21,177 $ 18,827
Class B Common Stock                  
Class Of Stock [Line Items]                  
Share conversion, Shares               (52,000) (59,000)
Common stock issued 241,628 13,468 947         13,000  
Class B Common Stock | Resale And Registration Rights Agreement                  
Class Of Stock [Line Items]                  
Share conversion, Shares 24,119   2,000   26,008        
Class A Common Stock                  
Class Of Stock [Line Items]                  
Share conversion, Shares               52,000 59,000
Common stock issued     3,896 1,000          
Silvercrest L.P                  
Class Of Stock [Line Items]                  
Accrued partner incentive allocations           $ 6,189 $ 5,169 $ 17,667 $ 14,197