Quarterly report pursuant to Section 13 or 15(d)

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

v3.2.0.727
Share-Based Compensation - Summary of Stock Options Outstanding under Plans (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2015
Mar. 31, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]            
Number of Shares, Options outstanding at beginning of period 583,665 603,872   603,872    
Number of Shares, Options granted 28,000     28,000    
Number of Shares, Options exercised (6,874)   (18,500) (26,455) (33,695)  
Number of Shares, Options forfeited (51,126)     (51,627)    
Number of Shares, Options expired (225)     (350)    
Number of Shares, Options outstanding at end of period 553,440 583,665   553,440   603,872
Number of Shares, Options exercisable at end of period 216,289     216,289    
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) $ 24.09 $ 23.78   $ 23.78    
Weighted-Average Exercise Price Per Share, Options granted (in usd per share) 23.47     23.47    
Weighted-Average Exercise Price Per Share, Options exercised (in usd per share) 12.54     13.77    
Weighted-Average Exercise Price Per Share, Options forfeited (in usd per share) 21.20     21.12    
Weighted-Average Exercise Price Per Share, Options expired (in usd per share) 144.00     144.00    
Weighted-Average Exercise Price Per Share, Options outstanding at end of period (in usd per share) 24.42 $ 24.09   24.42   $ 23.78
Weighted-Average Exercise Price Per Share, Options exercisable at end of period (in usd per share) $ 34.63     $ 34.63    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term [Abstract]            
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualLife 7 years 9 months 18 days 8 years   7 years 9 months 18 days   8 years
Weighted-Average Remaining Contractual Life, Options granted 9 years 10 months 24 days     9 years 10 months 24 days    
Weighted-Average Remaining Contractual Life, Options exercised 7 years 6 months     7 years 8 months 12 days    
Weighted-Average Remaining Contractual Life, Options forfeited 8 years 10 months 24 days     8 years 10 months 24 days    
Weighted-Average Remaining Contractual Life, Options expired 9 months 18 days     9 months 18 days    
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualLife 7 years 9 months 18 days 8 years   7 years 9 months 18 days   8 years
Weighted-Average Remaining Contractual Life, Options exercisable at end of period 6 years 8 months 12 days     6 years 8 months 12 days    
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at beginning of period $ 2,383 $ 2,853   $ 2,853    
Aggregate Intrinsic Value of In-the-Money Options, Options outstanding at end of period 4,116 $ 2,383   4,116   $ 2,853
Aggregate Intrinsic Value of In-the-Money Options, Options exercisable at end of period $ 1,764     $ 1,764    
Intrinsic value represents the excess of the closing stock price related to options outstanding (in usd per share) $ 24.84 $ 21.15   $ 24.84   $ 21.81