Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Additional Information (Detail)

v3.8.0.1
Share-Based Compensation - Additional Information (Detail)
12 Months Ended
Dec. 31, 2017
USD ($)
Plan
$ / shares
shares
Dec. 31, 2016
USD ($)
$ / shares
shares
Dec. 31, 2015
USD ($)
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of share-based compensation plans | Plan 4    
Common shares authorized under 2014 Stock Incentive Plan | shares 8,700,000    
Common shares remain for future issuance under share-based compensation plans | shares 4,200,000    
Realized income tax benefit for all awards $ 9,400,000 $ 14,800,000 $ 16,600,000
Awards granted | shares 0 0 0
Total vesting date fair value of stock units $ 2,000,000 $ 2,100,000 $ 1,300,000
Reserved for issuance under employee stock purchase plan | shares 2,000,000    
Future issuance of employee stock purchase plan | shares 1,700,000    
Percent of fair market value for which eligible employees can purchase common shares under employee stock purchase plan 85.00%    
Performance conditions [Member] | First Succeeding Year [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance stock unit awards vesting percentage 20.00%    
Performance conditions [Member] | Second Succeeding Year [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance stock unit awards vesting percentage 20.00%    
Performance conditions [Member] | Third Succeeding Year [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance stock unit awards vesting percentage 60.00%    
Independent Director Stock Units [Member] | Performance conditions [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period beginning from the grant date 1 year    
Chief Executive Officer [Member] | Performance conditions [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance stock unit awards vesting date Dec. 31, 2019    
Chief Executive Officer [Member] | Performance conditions [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance stock unit awards vesting percentage 0.00%    
Chief Executive Officer [Member] | Performance conditions [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance stock unit awards vesting percentage 200.00%    
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period beginning from the grant date 5 years    
Contractual term 10 years    
SARs [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Contractual term 10 years    
Awards granted | shares 0 0 0
SARs [Member] | Stock Incentive Plan Other [Member] | Performance conditions [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period beginning from the grant date 3 years    
Service condition awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 24,400,000 $ 23,900,000 $ 26,800,000
Unrecognized compensation cost on non-vested stock awards $ 29,200,000    
Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition 1 year 4 months 24 days    
Weighted-average grant date fair value of SARs granted | $ / shares $ 28.64 $ 29.33 $ 12.57
Total intrinsic value of awards exercised for options and SARs $ 122,800,000 $ 32,300,000 $ 25,500,000
Performance condition awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense 16,400,000 $ 15,900,000 $ 17,800,000
Unrecognized compensation cost on non-vested stock awards $ 15,100,000    
Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition 1 year 8 months 12 days    
Weighted-average grant date fair value of SARs granted | $ / shares $ 28.32 $ 29.69 $ 13.65
Total intrinsic value of awards exercised for options and SARs $ 3,100,000 $ 700,000  
Market condition awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 1,300,000 400,000 $ 300,000
Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition 2 months 12 days    
Total intrinsic value of awards exercised for options and SARs $ 0 0 11,400,000
Market condition awards [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation cost on non-vested stock awards 100,000    
Market and performance condition awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 0 $ 0 $ 0
Management Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Additional awards | shares 0    
2004 Stock Incentive Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Additional awards | shares 0    
2005 Stock Incentive Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Additional awards | shares 0    
Stock Incentive Plan [Member] | Performance conditions [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period beginning from the grant date 3 years    
Contractual term 3 years