v3.7.0.1
Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Mar. 31, 2014
Number of options        
Number of Options outstanding, Beginning Balance 210,297 102,817 66,173  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross 242,068 127,966 76,512  
Number of Options, Exercised (263) (11,986) (39,868)  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number 98,788      
Number of Options outstanding, Ending Balance 451,668 210,297 102,817 66,173
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number 442,808      
Options outstanding, Weighted Average Remaining Contract Term        
Options outstanding, Weighted Average Remaining Contract Term (Years) 8 years 4 months 24 days 8 years 6 months 7 years 1 year 4 months 24 days
Options exercisable, Weighted Average Remaining Contract Term (Years) 7 years 2 months 12 days      
Weighted average exercise price        
Options outstanding, Weighted Average Exercise Price, Beginning Balance $ 67.54 $ 55.86 $ 14.77  
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price 57.60 68.40 69.85  
Weighted Average Exercise Price, Exercised 18.25 14.64 14.50  
Options outstanding, Weighted Average Exercise Price, Ending Balance 62.29 $ 67.54 $ 55.86 $ 14.77
Options exercisable, Weighted Average Exercise Price $ 66.55      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term 8 years 4 months 24 days      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price $ 62.36      
Aggregate intrinsic value        
Options outstanding, Aggregate Intrinsic Value, Beginning Balance $ 218 $ 1,291 $ 3,608  
Aggregate Intrinsic Value, Exercised 12 639 1,819  
Options outstanding, Aggregate Intrinsic Value, Ending Balance 7,520 $ 218 $ 1,291 $ 3,608
Options exercisable, Aggregate Intrinsic Value 1,224      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value $ 7,340      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period (434) (8,500)