Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Summary of Activities Under Share-Based Compensation Plans (Parenthetical) (Detail)

v3.19.3.a.u2
Share-Based Compensation - Summary of Activities Under Share-Based Compensation Plans (Parenthetical) (Detail) - shares
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Shares, Expected to vest 1,575,000  
Number of Shares, Forfeited 520,000  
Number of Shares, Vested 241,000  
Market condition awards [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding SARs 100,000 100,000
Exercisable SARs 100,000  
Performance condition SARs [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding SARs 2,900,000 3,100,000
Forfeited SARs 200,000  
Exercisable SARs 2,400,000  
Performance condition SARs [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Exercised SARs 100,000  
Performance Based Stock Unit Awards [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of Shares, Expected to vest 240,156  
Number of Shares, Forfeited 402,291  
Number of Shares, Vested 40,297  
Number of shares, forfeited, relate to adjustments 45,259  
Performance Based Stock Unit Awards [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of share based payment awards other than options outstanding and nonvested that can vest maximum 475,430 708,836
Number of share based payment awards other than options that can vest maximum 209,182