Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

v3.19.3
Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended
Aug. 31, 2019
Jul. 31, 2019
Jun. 30, 2019
May 31, 2019
Mar. 31, 2019
Jan. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Sep. 30, 2019
Sep. 30, 2018
Class Of Stock [Line Items]                            
Partnership distributions, amount             $ 1,626     $ 1,529     $ 7,385 $ 6,541
Distributions of partner incentive allocations of net income                         27,199 24,935
Class B Common Stock                            
Class Of Stock [Line Items]                            
Share conversion, Shares             (556,000) (87,000) (17,000) (40,000) (45,000) (117,000)    
Issuance of common stock 241,624     948     663,000   2,000   6,000      
Class B Common Stock | Resale And Registration Rights Agreement                            
Class Of Stock [Line Items]                            
Share conversion, Shares 556,293   2,386 84,268 17,074                  
Class B Common Stock | Neosho                            
Class Of Stock [Line Items]                            
Issuance of Class B common stock in connection with the Acquisition           1,516                
Class B Common Stock | Cortina                            
Class Of Stock [Line Items]                            
Issuance of Class B common stock in connection with the Acquisition   662,713                        
Class B Common Stock | Cortina | Resale And Registration Rights Agreement                            
Class Of Stock [Line Items]                            
Issuance of Class B common stock in connection with the Acquisition   662,713                        
Class A Common Stock                            
Class Of Stock [Line Items]                            
Share conversion, Shares             556,000 87,000 17,000 40,000 45,000 117,000    
Issuance of common stock       1,896                    
Silvercrest L.P                            
Class Of Stock [Line Items]                            
Accrued partner incentive allocations             $ 7,115     $ 7,154     $ 18,766 $ 21,055