Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation (Textual) (Detail)

v3.6.0.2
Share-Based Compensation (Textual) (Detail) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares available for future awards 1,098,514    
Unrecognized compensation expense related to unvested portion of stock options $ 600,000    
Weighted average period of recognition of unrecognized compensation expense 10 months    
Intrinsic value of options exercised $ 3,400,000 $ 17,700,000 $ 20,600,000
Weighted average vested options 930,544    
Weighted average exercise price of vested stock $ 15.01    
Intrinsic value of options vested and expected to vest $ 9,000,000    
Weighted average remaining contractual term 2 years 1 month    
Weighted average shares exercisable 816,691 737,032 1,051,616
Weighted average exercise price (in dollars per share) $ 14.54 $ 14.40 $ 14.13
Intrinsic value of options exercisable $ 16,500,000    
Weighted average remaining contractual term, exercisable 2 years    
Compensation expense associated with the ESPP $ 200,000 $ 200,000 $ 200,000
Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share based compensation, expiration period 6 years    
Share based compensation, vesting period 4 years    
Intrinsic value of options vested and expected to vest $ 18,400,000    
Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average period of recognition of unrecognized compensation expense 2 years 2 months    
Intrinsic value of options vested and expected to vest   10,300,000 6,000,000
Weighted average shares exercisable 816,691    
Unrecognized compensation of unvested awards $ 9,200,000    
Fair market value of outstanding awards $ 17,600,000    
Employee Stock Purchase Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Employee maximum withholding rate (percent) 15.00%    
Eligible compensation of employees $ 10,625    
Purchase price for shares acquired 85.00%    
Shares reserved for future issuance 165,740    
Offering price, percentage of fair market value 85.00%    
Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average period of recognition of unrecognized compensation expense 1 year 7 months    
Intrinsic value of options vested and expected to vest $ 900,000 $ 900,000 $ 400,000
Unrecognized compensation of unvested awards 500,000    
Aggregate intrinsic value of outstanding restricted stock units $ 1,000,000