Annual report pursuant to Section 13 and 15(d)

Capital Stock - Additional Information (Detail)

v2.4.0.6
Capital Stock - Additional Information (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
12 Months Ended 1 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Restricted Stock
Dec. 31, 2011
Restricted Stock
Dec. 31, 2010
Restricted Stock
Dec. 31, 2012
Restricted Stock
Certain of the restricted stock granted to employees
Dec. 31, 2012
Restricted Stock
Remaining restricted stock granted to employees
Dec. 31, 2012
Restricted Stock
Directors And Employees
Dec. 31, 2012
Restricted Stock Units (RSUs)
Dec. 31, 2011
Restricted Stock Units (RSUs)
Dec. 31, 2010
Restricted Stock Units (RSUs)
Dec. 31, 2012
Restricted Stock Units (RSUs)
Amended And Restated Long Term Incentive Plan
Dec. 31, 2011
Restricted Stock Units (RSUs)
Amended And Restated Long Term Incentive Plan
Dec. 31, 2010
Restricted Stock Units (RSUs)
Amended And Restated Long Term Incentive Plan
Dec. 31, 2012
2008 Grant
Dec. 31, 2010
2008 Grant
Dec. 31, 2010
2009 Grant
Jun. 30, 2010
Colombian Partners
Stockholders Equity Note [Line Items]                                      
Common stock issued, shares                                     1,112,723
Intrinsic value of options exercised $ 1,070 $ 699 $ 9,836                                
Recognized tax benefit on options exercised 449 238 2,680                                
Average remaining contractual life of options outstanding 2 years                                    
Shares of Restricted Stock Granted 653,229 424,436 683,921           653,229                    
Minimum fair value of restricted stock granted       $ 21.63           $ 18.34                  
Maximum fair value of restricted stock granted       $ 22.97           $ 21.63                  
Minimum forfeiture rate for restricted stock awards       0.00%           0.00%                  
Maximum forfeiture rate for restricted stock awards       5.00%           5.00%                  
Award vesting period range for restricted stock granted to employees             3 years 4 years                      
Award vesting period range for restricted stock granted to directors       Over one year                              
Compensation expense       10,637 6,591 4,928                          
Total fair value of shares vested during the period       9,702 5,658 3,272       4,400                  
Recognized tax benefits related to shares vested during the period       4,075 2,188 1,087       1,848                  
Unrecognized compensation expense related to restricted stock awards       18,341                              
Compensation expense recognition period (in years)       2 years           2 years                  
Number of hypothetical shares of common stock                   994,671     152,955 153,727 396,429        
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%                  
Incremental compensation expense     435                                
Percentage of IRR expected restricted stock units grants 12.50%                             12.50%   12.50%  
Additional compensation expense recognized upon determination that maximum IRR level is reached 1,609                               823 377  
Restricted stock unit awards vested 489,033 288,204 190,589             196,051                  
Restricted stock unit convertion into share of common stock, conversion ratio                   1                  
Dividends paid on vested restricted stock units                   600                  
Compensation expense                   4,433 3,101 3,424              
Actual cumulative forfeitures (in units)                   11,608                  
Assumed maximum IRR for all grants                   12.50%                  
Unrecognized Compensation expense related to outstanding restricted stock                   $ 4,890