Annual report pursuant to Section 13 and 15(d)

Capital Stock - Additional Information (Detail)

v3.19.3.a.u2
Capital Stock - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Stockholders Equity Note [Line Items]      
Preferred stock, shares issued 0    
Preferred stock, shares outstanding 0    
Restricted Stock      
Stockholders Equity Note [Line Items]      
Number of restricted shares 315,899 328,734 246,534
Market value of common stock on the dates of grant $ 37.34 $ 38.72 $ 41.70
Unrecognized compensation expense $ 15,524    
Remaining Compensation Expense recognition period (in years) 2 years    
Restricted Stock | Directors      
Stockholders Equity Note [Line Items]      
Award vesting period for restricted stock granted 1 year    
Restricted Stock | Minimum      
Stockholders Equity Note [Line Items]      
Market value of common stock on the dates of grant $ 34.01    
Forfeiture rate for restricted stock awards 0.00%    
Restricted Stock | Minimum | Employees      
Stockholders Equity Note [Line Items]      
Award vesting period for restricted stock granted 1 year    
Restricted Stock | Maximum      
Stockholders Equity Note [Line Items]      
Market value of common stock on the dates of grant $ 41.61    
Forfeiture rate for restricted stock awards 10.00%    
Restricted Stock | Maximum | Employees      
Stockholders Equity Note [Line Items]      
Award vesting period for restricted stock granted 4 years    
Restricted Stock Units (RSUs)      
Stockholders Equity Note [Line Items]      
Market value of common stock on the dates of grant $ 36.77   $ 42.37
Unrecognized compensation expense   $ 9,872  
Remaining Compensation Expense recognition period (in years) 2 years    
Number of hypothetical shares of common stock 306,651 228,194 175,634
Share-based compensation arrangement by share-based payment award, description The financial performance factors are based on an implied equity value concept that determines an internal rate of return (“IRR”) for a two year measurement period, as defined in the award agreement, based on a formula utilizing a multiple of Adjusted EBITDA subject to certain specified adjustments (as defined in the restricted stock unit award agreement).    
Share-based compensation arrangement by share-based payment award, vesting condition All payouts of restricted stock units that vest will be subject to an additional service requirement and will be paid in the form of common stock if the participant continues to provide services through the fourth anniversary of the grant date.    
Internal rate of return, performance period 2 years    
Percentage of IRR expected 9.00%    
Percentage of IRR, which is the threshold, before modification 7.00%    
Percentage of IRR, which is the target before modification 9.50%    
Percentage of IRR, which is the maximum before modification 13.00%    
Percentage of IRR, which is the threshold 6.00% 6.00% 6.00%
Percentage of IRR, which is the target 8.00% 8.00% 8.00%
Percentage of IRR, which is the maximum 14.00% 14.00% 14.00%
Number of hypothetical shares of common stock at maximum IRR level 749,895    
Actual cumulative forfeitures (in units) 6,195    
Restricted Stock Units (RSUs) | Stock Grants 2016      
Stockholders Equity Note [Line Items]      
Impact of modification of awards $ 132    
Achieved Percentage of IRR 7.20%    
Impact of final performance measure $ 563    
Restricted Stock Units (RSUs) | Stock Grant 2017      
Stockholders Equity Note [Line Items]      
Achieved Percentage of IRR 9.30%    
Restricted Stock Units (RSUs) | Stock Grant 2018      
Stockholders Equity Note [Line Items]      
Achieved Percentage of IRR 8.00%    
Restricted Stock Units (RSUs) | Minimum      
Stockholders Equity Note [Line Items]      
Market value of common stock on the dates of grant   $ 37.55  
Expected forfeiture rate 0.00% 0.00% 0.00%
Restricted Stock Units (RSUs) | Maximum      
Stockholders Equity Note [Line Items]      
Market value of common stock on the dates of grant   $ 39.03  
Expected forfeiture rate 5.00% 5.00% 5.00%