Annual report pursuant to Section 13 and 15(d)

Equity - Additional Information (Detail)

v3.8.0.1
Equity - Additional Information (Detail) - USD ($)
$ in Thousands
 1 Months Ended 12 Months Ended
Nov. 30, 2017
Aug. 31, 2017
Jun. 30, 2017
May 31, 2017
Apr. 30, 2017
Mar. 31, 2017
May 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Class Of Stock [Line Items]                    
Partnership distributions, amount               $ 6,205 $ 5,761 $ 5,546
Distributions of partner incentive allocations of net income               $ 21,177 $ 18,827 $ 18,568
Class B Common Stock                    
Class Of Stock [Line Items]                    
Share Conversion, Shares               (63,000) (84,000) (211,000)
Common stock issued   241,628 13,468 947     947 13,000    
Class B Common Stock | Resale And Registration Rights Agreement                    
Class Of Stock [Line Items]                    
Share Conversion, Shares 10,900 24,119   2,000   26,008        
Class A Common Stock                    
Class Of Stock [Line Items]                    
Share Conversion, Shares               63,000 84,000 222,000
Common stock issued       3,896 1,000          
Silvercrest L.P                    
Class Of Stock [Line Items]                    
Accrued partner incentive allocations               $ 25,101 $ 20,238 $ 18,535