Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.20.2
Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended
Aug. 31, 2020
Jun. 30, 2020
May 31, 2020
Mar. 31, 2020
Feb. 29, 2020
Sep. 30, 2020
Jun. 30, 2020
Mar. 31, 2020
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Sep. 30, 2020
Sep. 30, 2019
Class Of Stock [Line Items]                          
Partnership distributions, amount           $ 1,497     $ 1,626     $ 6,521 $ 7,385
Distributions of partner incentive allocations of net income                       27,236 27,199
Class B Common Stock                          
Class Of Stock [Line Items]                          
Share conversion, Shares 24,191   7,355     (24,000) (12,000) (176,000) (556,000) (87,000) (17,000)    
Issuance of common stock     9,546           663,000   2,000    
Class B Common Stock | Resale And Registration Rights Agreement                          
Class Of Stock [Line Items]                          
Share conversion, Shares 24,191 5,400 7,355 20,662 155,224                
Class A Common Stock                          
Class Of Stock [Line Items]                          
Share conversion, Shares           24,000 12,000 176,000 556,000 87,000 17,000    
Issuance of common stock     1,896                    
Silvercrest L.P                          
Class Of Stock [Line Items]                          
Accrued partner incentive allocations           $ 7,121     $ 7,115     $ 20,055 $ 18,766