XML 78 R63.htm IDEA: XBRL DOCUMENT v3.10.0.1
Stock-Based Compensation - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Approximate number of shares employees purchased under the Employee Stock Purchase Plan   874,235    
2014 Stock Incentive Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Total aggregate number of shares of common stock that may be issued 12,840,000 12,840,000    
Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Compensation cost recognition period for unvested awards 1 year 6 months      
Unrecognized compensation cost related to unvested awards $ 1.6 $ 1.6 $ 1.8 $ 1.2
Vesting period   3 years    
Number of shares or rights issued   80,570 86,614 89,850
Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member] | Share-Based Compensation Award, Tranche One [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based Compensation vesting percentage   33.33%    
Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member] | Share-Based Compensation Award, Tranche Two [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based Compensation vesting percentage   33.33%    
Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member] | Share-Based Compensation Award, Tranche Three [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based Compensation vesting percentage   33.33%    
Stock Appreciation Rights [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Unrecognized compensation cost related to unvested awards 0.4 $ 0.4    
Maximum contractual term   10 years    
Fair value assumptions method used   Black-Scholes option-pricing model    
Number of shares or rights issued       0
Weighted-average fair value of grants   $ 22.09 $ 13.99  
Time-Based Restricted Stock and Time-Based Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Compensation cost recognition period for unvested awards   2 years 8 months 12 days    
Unrecognized compensation cost related to unvested awards $ 5.1 $ 5.1    
Total fair value of restricted shares vested   $ 4.2 $ 5.5 $ 1.7
Number of shares or rights issued   87,264 72,402 115,748
Employee Stock Purchase Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Total aggregate number of shares of common stock that may be issued 1,200,000 1,200,000    
Percentage of market price on lesser of either first day of calendar quarter or last day of calendar quarter for purchase price   85.00%    
Percentage of gross compensation eligible employees may elect to participate in the plan 15.00% 15.00%    
Minimum [Member] | Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Percentage of target number of shares that will vest   0.00%    
Maximum [Member] | Performance-Based Restricted Stock and Performance-Based Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Percentage of target number of shares that will vest   200.00%