Quarterly report pursuant to Section 13 or 15(d)

Treasury Stock and Share Based Awards - Additional Information (Detail)

v2.4.0.8
Treasury Stock and Share Based Awards - Additional Information (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Stockholders Equity Note [Line Items]    
Number of stock options exercised 14,584  
Weighted average exercise price of options exercised $ 7.63  
Intrinsic value of options exercised $ 296  
Tax benefit recognized on stock option exercised 124  
Stock options outstanding 0  
Restricted Stock
   
Stockholders Equity Note [Line Items]    
Shares of Restricted Stock Granted 268,257  
Weighted average market value of common stock on the date of grant $ 28.90  
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 18,571  
Recognized tax benefits related to shares vested during the period 7,109  
Compensation expense 7,264 7,823
Unrecognized compensation expense 14,589  
Compensation expense recognition period (in years) 2 years  
Restricted stock unit awards vested 619,307  
Restricted Stock | Minimum
   
Stockholders Equity Note [Line Items]    
Weighted average market value of common stock on the date of grant $ 28.54  
Restricted Stock | Maximum
   
Stockholders Equity Note [Line Items]    
Weighted average market value of common stock on the date of grant $ 35.49  
Restricted Stock | Board of Directors
   
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 Units (RSUs)
   
Stockholders Equity Note [Line Items]    
Weighted average market value of common stock on the date of grant $ 28.54  
Total fair value of shares vested during the period 11,312  
Recognized tax benefits related to shares vested during the period 4,751  
Compensation expense 2,300 2,523
Unrecognized compensation expense 5,383  
Compensation expense recognition period (in years) 2 years  
Number of hypothetical shares of common stock 577,097  
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%  
Restricted stock unit awards vested 392,238  
Restricted stock unit conversion into share of common stock, conversion ratio 1  
Dividends paid on vested restricted stock units $ 1,341  
Restricted Stock Units (RSUs) | Minimum
   
Stockholders Equity Note [Line Items]    
Expected forfeiture rate 0.00%  
Restricted Stock Units (RSUs) | Maximum
   
Stockholders Equity Note [Line Items]    
Expected forfeiture rate 5.00%  
Restricted Stock Units (RSUs) | Employee
   
Stockholders Equity Note [Line Items]    
Number of hypothetical shares of common stock 197,515