Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail)

v3.5.0.2
Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]              
Number of Shares, Options outstanding at beginning of period       484,439   510,148  
Number of Shares, Options exercised       (18,000) (6,874) (40,209) (26,455)
Number of Shares, Options forfeited           (125)  
Number of Shares, Options expired       (15,875)   (19,250)  
Number of Shares, Options outstanding at end of period 450,564 484,439 510,148 450,564   450,564  
Number of Shares, Options exercisable at end of period 301,915     301,915   301,915  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]              
Weighted-Average Exercise Price Per Share, Options outstanding at beginning of period (in usd per share)       $ 23.76   $ 24.38  
Weighted-Average Exercise Price Per Share, Options exercised (in usd per share)       12.30   13.99  
Weighted-Average Exercise Price Per Share, Options forfeited (in usd per share)           144.00  
Weighted-Average Exercise Price Per Share, Options expired (in usd per share)       144.18   148.36  
Weighted-Average Exercise Price Per Share, Options outstanding at end of period (in usd per share) $ 19.97 $ 23.76 $ 24.38 19.97   19.97  
Weighted-Average Exercise Price Per Share, Options exercisable at end of period (in usd per share) $ 20.73     $ 20.73   $ 20.73  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term [Abstract]              
Weighted-Average Remaining Contractual Life, Options outstanding at beginning of period 7 years 2 months 7 years 1 month 7 years 3 months 18 days        
Weighted-Average Remaining Contractual Life, Options exercised       5 years 11 months   6 years 5 months  
Weighted-Average Remaining Contractual Life, Options forfeited           2 months  
Weighted-Average Remaining Contractual Life, Options expired       2 months   1 month  
Weighted-Average Remaining Contractual Life, Options outstanding at end of period 7 years 2 months 7 years 1 month 7 years 3 months 18 days        
Weighted-Average Remaining Contractual Life, Options exercisable at end of period 6 years 11 months            
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at beginning of period       $ 2,303   $ 3,219  
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at end of period $ 2,727 $ 2,303 $ 3,219 2,727   2,727  
Aggregate Intrinsic Value of In-the-Money Options, Options exercisable at end of period $ 1,972     $ 1,972   $ 1,972  
Intrinsic value represents the excess of the closing stock price related to options outstanding (in usd per share) $ 23.49 $ 22.02 $ 23.72 $ 23.49   $ 23.49