Equity - Additional Information (Details)
 12 Months Ended
Feb. 12, 2018
USD ($)
Item
$ / shares
shares
Dec. 31, 2019
USD ($)
Item
$ / shares
shares
Dec. 31, 2018
USD ($)
$ / shares
shares
Aug. 31, 2019
USD ($)
Mar. 22, 2019
USD ($)
Dec. 31, 2017
USD ($)
Pre-IPO Number of classes of common stock | Item   1        
Common stock, par value | $ / shares   $ 0.01        
Preferred stock, shares authorized | shares 10,000,000          
Preferred stock, par value | $ / shares $ 0.01          
Stock issuance costs included in prepaid expenses           $ 2,900,000
Preferred stock, shares issued | shares   0        
Conversion basis of Class B Shares into Class A shares $ 1,000          
Threshold for number of class B shares as a percent of the aggregate class A shares for conversion 10.00%          
Number of shares acquired | shares   1,685,155        
Average cost of acquired shares (in dollars per share) | $ / shares   $ 12.77        
Cost of acquired shares   $ 21,500,000        
Remaining authorized amount for share repurchase program   $ 8,500,000        
IPO            
Legal, accounting and other costs included in offering costs           $ 4,600,000
Class A            
Common stock, par value | $ / shares $ 0.01 $ 0.01 $ 0.01      
Common stock, shares authorized | shares 400,000,000 400,000,000 400,000,000      
Offering costs     $ 4,287,000      
Number of votes for each share of common stock | Item 1          
Authorized amount for share repurchase program       $ 15,000,000 $ 15,000,000  
Class B            
Common stock, par value | $ / shares $ 0.01 $ 0.01 $ 0.01      
Common stock, shares authorized | shares 200,000,000 200,000,000 200,000,000      
Offering costs     $ 4,300,000      
Number of votes for each share of common stock | Item 10