Annual report pursuant to Section 13 and 15(d)

Capital Stock - Additional Information (Detail)

v2.4.0.8
Capital Stock - Additional Information (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Stockholders Equity Note [Line Items]      
Intrinsic value of options exercised $ 168 $ 1,070 $ 699
Average remaining contractual life of options outstanding 9 months    
Tax benefit recognized on stock option exercised 71 449 238
Restricted Stock
     
Stockholders Equity Note [Line Items]      
Shares of Restricted Stock Granted 271,532 653,229 424,436
Market value of common stock on the date of grant $ 30.09 $ 21.70 $ 19.45
Minimum forfeiture rate for restricted stock awards 0.00%    
Maximum forfeiture rate for restricted stock awards 5.00%    
Compensation expense 12,738 10,637 6,591
Total fair value of shares vested during the period 10,161 9,702 5,658
Recognized tax benefits related to shares vested during the period 4,268 4,075 2,188
Unrecognized compensation expense 14,395    
Compensation expense recognition period (in years) 2 years    
Restricted stock awards vested 522,129 489,033 288,204
Shares of restricted stock, forfeited 22,653 14,423 1,920
Restricted Stock | Director
     
Stockholders Equity Note [Line Items]      
Award vesting period for restricted stock granted 1 year    
Restricted Stock | Employee Scenario One
     
Stockholders Equity Note [Line Items]      
Award vesting period for restricted stock granted 3 years    
Restricted Stock | Employee Scenario Two
     
Stockholders Equity Note [Line Items]      
Award vesting period for restricted stock granted 4 years    
Restricted Stock | Minimum
     
Stockholders Equity Note [Line Items]      
Market value of common stock on the date of grant $ 27.92    
Restricted Stock | Maximum
     
Stockholders Equity Note [Line Items]      
Market value of common stock on the date of grant $ 33.74    
Restricted Stock Units (RSUs)
     
Stockholders Equity Note [Line Items]      
Minimum forfeiture rate for restricted stock awards 0.00%    
Maximum forfeiture rate for restricted stock awards 5.00%    
Total fair value of shares vested during the period 8,723 4,400  
Recognized tax benefits related to shares vested during the period 3,663 1,848  
Compensation expense recognition period (in years) 1 year    
Number of hypothetical shares of common stock 802,529    
Percentage of IRR, which is the threshold 8.50%    
Percentage of IRR, which is the target 10.50%    
Percentage of IRR, which is the maximum 12.50%    
Percentage of restricted stock units vest 100.00%    
Percentage of IRR excpected 11.50%    
Restricted stock awards vested 295,751 196,051  
Restricted stock unit conversion into share of common stock, conversion ratio 1 1  
Dividends paid on vested restricted stock units 939 600  
Shares of restricted stock, forfeited 11,498    
Compensation expense 4,148 4,433 3,101
Actual cumulative forfeitures (in units) 11,498    
Assumed maximum IRR for all grants 12.50%    
Unrecognized Compensation expense related to outstanding restricted stock $ 4,048    
Restricted Stock Units (RSUs) | Amended And Restated Long Term Incentive Plan
     
Stockholders Equity Note [Line Items]      
Number of hypothetical shares of common stock 115,107 152,955 153,727
Restricted Stock Units (RSUs) | Minimum
     
Stockholders Equity Note [Line Items]      
Market value of common stock on the date of grant $ 19.35    
Restricted Stock Units (RSUs) | Maximum
     
Stockholders Equity Note [Line Items]      
Market value of common stock on the date of grant $ 29.44