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 9 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]            
Number of Shares, Options outstanding at beginning of period     450,564   510,148  
Number of Shares, Options exercised     (2,375) (13,311) (42,584) (39,766)
Number of Shares, Options forfeited         (125)  
Number of Shares, Options expired     (1,875)   (21,125)  
Number of Shares, Options outstanding at end of period 450,564 510,148 446,314   446,314  
Number of Shares, Options exercisable at end of period     391,642   391,642  
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)     $ 19.97   $ 24.38  
Weighted-Average Exercise Price Per Share, Options exercised (in usd per share)     12.54   13.90  
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)     152.24   148.70  
Weighted-Average Exercise Price Per Share, Options outstanding at end of period (in usd per share) $ 19.97 $ 24.38 19.46   19.46  
Weighted-Average Exercise Price Per Share, Options exercisable at end of period (in usd per share)     $ 19.14   $ 19.14  
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 3 months 18 days 6 years 11 months   6 years 11 months  
Weighted-Average Remaining Contractual Life, Options exercised     6 years 2 months   6 years 1 month  
Weighted-Average Remaining Contractual Life, Options forfeited         1 day  
Weighted-Average Remaining Contractual Life, Options expired     1 day   1 day  
Weighted-Average Remaining Contractual Life, Options outstanding at end of period 7 years 2 months 7 years 3 months 18 days 6 years 11 months   6 years 11 months  
Weighted-Average Remaining Contractual Life, Options exercisable at end of period     6 years 9 months   6 years 9 months  
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at beginning of period     $ 2,727   $ 3,219  
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at end of period $ 2,727 $ 3,219 3,952   3,952  
Aggregate Intrinsic Value of In-the-Money Options, Options exercisable at end of period     $ 3,666   $ 3,666  
Intrinsic value represents the excess of the closing stock price related to options outstanding (in usd per share) $ 23.49 $ 23.72 $ 26.34   $ 26.34