Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

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Equity - Additional Information (Detail) - USD ($)
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2023
Aug. 31, 2023
Jun. 30, 2023
May 31, 2023
Mar. 31, 2023
Sep. 30, 2023
Jun. 30, 2023
Mar. 31, 2023
Sep. 30, 2022
Sep. 30, 2023
Sep. 30, 2022
Dec. 31, 2022
Jul. 29, 2021
Class Of Stock [Line Items]                          
Partnership distributions, amount           $ 1,419,000     $ 2,059,000 $ 7,759,000 $ 8,268,000    
Distributions of partner incentive allocations of net income                   32,262,000 $ 34,429,000    
Treasury stock, aggregate price           773,000 $ 3,345,000   5,240,000 $ 15,057,000   $ 9,295,000  
Non-Qualified Stock Options                          
Class Of Stock [Line Items]                          
Stock issued during period, shares, stock options exercised                   105,398 0    
Class B Common Stock                          
Class Of Stock [Line Items]                          
Stock issued during period, shares, acquisitions       1,376                  
Class B Common Stock | Restricted Stock                          
Class Of Stock [Line Items]                          
Issuance of common stock       50,081                  
Class B Common Stock | Non-Qualified Stock Options                          
Class Of Stock [Line Items]                          
Stock issued during period, shares, stock options exercised 22,070                        
Class B Common Stock | Neosho                          
Class Of Stock [Line Items]                          
Stock issued during period, shares, acquisitions       1,376                  
Class B Common Stock | Resale And Registration Rights Agreement                          
Class Of Stock [Line Items]                          
Share conversion, Shares   6,636 21,243 44,669 1,555                
Class A Common Stock                          
Class Of Stock [Line Items]                          
Treasury stock, purchased   37,820 106,096 60,028 95,729         808,455   508,782  
Treasury stock, aggregate price               $ 1,644,000          
Conversion of Stock, Shares Issued   6,636 21,243 44,669 1,555                
Class A Common Stock | Maximum                          
Class Of Stock [Line Items]                          
Stock repurchase program, authorized amount                         $ 15,000,000
Class A Common Stock | Restricted Stock                          
Class Of Stock [Line Items]                          
Issuance of common stock         8,242                
Silvercrest L.P                          
Class Of Stock [Line Items]                          
Accrued partner incentive allocations           $ 6,983,000     $ 6,968,000 $ 20,476,000 $ 23,918,000