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Stock-Based Compensation - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2013
Employees
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares available for grant under stock option plans 11,165,480    
Expected dividend yield 0.00% 1.20% 1.10%
Weighted-average grant-date fair values of stock options granted $ 8.21 $ 6.58 $ 6.16
Number of groups within the employee population 2    
Percentage of stock options granted to senior management expected to vest 71.00%    
Percentage of stock options granted to all other employees expected to vest 69.00%    
Estimated forfeiture rate for unvested options for senior management 12.00%    
Estimated forfeiture rate for unvested options for all non-senior management 13.00%    
Increase in compensation expense due to revised estimated forfeiture rates $ 300,000 $ 200,000  
Reduction in compensation expense due to revised estimated forfeiture rates     80,000
Stock-based compensation expense 10,620,000 8,520,000 8,068,000
Income tax benefit recognized related to stock-based compensation expense 3,482,000 2,772,000 2,660,000
Compensation expense was capitalized 0 0 0
Total intrinsic values of stock options exercised 32,096,000 16,296,000 20,108,000
Total fair values of stock options vested 9,717,000 9,362,000 10,202,000
Total unrecognized compensation expense related to non-vested stock options $ 8,464,000    
Weighted-average period for unrecognized compensation expense related to non-vested stock options (years) 1 year 2 months 5 days    
Stock Option and Incentive Plan [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expiration period of stock option plan 10 years    
Vesting period for stock option plans 4 years    
2015 Through Expected Life of Option [Member]
      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield 1.04%