Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans - 2013 Omnibus Equity Incentive Plan - Additional Information (Detail)

v3.20.4
Stock-Based Compensation Plans - 2013 Omnibus Equity Incentive Plan - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vested shares 284,503 400,616 333,724
2013 Omnibus Equity Incentive Plan [Member] | Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares issued under compensation plan 0    
Number of shares outstanding under compensation plan 0    
2013 Omnibus Equity Incentive Plan [Member] | Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 1 year    
2013 Omnibus Equity Incentive Plan [Member] | Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 5 years    
Vested shares 264,235    
Number of common stock shares withheld to pay employee statutory withholding taxes 62,566    
2013 Omnibus Equity Incentive Plan [Member] | SARs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares issued under compensation plan 0    
Number of shares outstanding under compensation plan 0    
2013 Omnibus Equity Incentive Plan [Member] | Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares issued under compensation plan 0    
Number of shares outstanding under compensation plan 0    
2013 Omnibus Equity Incentive Plan [Member] | Performance Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares issued under compensation plan 0    
Number of shares outstanding under compensation plan 0    
2013 Omnibus Equity Incentive Plan [Member] | Deferred stock units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vested shares 0    
Fair value of vested, during period $ 0.0 $ 0.0 $ 8.3
Fully vested deferred stock units remaining outstanding 341,566    
2013 Omnibus Equity Incentive Plan [Member] | Restricted Stock Units and Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fair value of vested, during period $ 8.9 $ 14.6 $ 11.1