Quarterly report pursuant to Section 13 or 15(d)

Stock Compensation - Additional Information (Detail)

v3.20.1
Stock Compensation - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Apr. 17, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 12,400 $ 8,900  
Stock redeemed, value 5,659 $ 5,816  
Unrecognized compensation cost related to nonvested common shares $ 106,300    
Weighted average period for recognition of cost 2 years 4 months 24 days    
Class A Common Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock redeemed, shares 171,120 170,073  
Stock redeemed, value $ 5,700 $ 5,800  
2017 Plan [Member] | Class A Common Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares reserved for issuance     10,000,000
2018 ESPP [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum percentage of employee's compensation to purchase common stock 15.00%    
Percentage of price of common stock purchased 85.00%    
2018 ESPP [Member] | Class A Common Stock [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares available for sale under employee stock purchase plan     5,000,000