Quarterly report pursuant to Section 13 or 15(d)

Stock Compensation - Additional Information (Detail)

v3.21.1
Stock Compensation - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Performance-Based Awards [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Performance period 3 years  
Performance-Based Awards [Member] | Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Payout percentage of performance awards 0.00%  
Performance-Based Awards [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Payout percentage of performance awards 200.00%  
2017 Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of shares that remain available for grant 5,121,800  
Recognized compensation expense $ 12.0 $ 12.4
Unrecognized compensation cost related to nonvested common shares $ 92.9  
Weighted average period for recognition of cost 2 years 21 days