Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Expense Stock-Based Compensation Expense - Unvested Shares (Details)

v3.8.0.1
Stock-Based Compensation Expense Stock-Based Compensation Expense - Unvested Shares (Details) - $ / shares
 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]        
Exercised, weighted average exercise price (in dollars per share)     $ 21.97  
Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]        
Options outstanding, beginning of period (in shares) 411,939.000 433,726 465,042  
Granted (in shares)   28,499    
Forfeited (in shares) (1,412) (2,802) (2,260)  
Options outstanding, end of period (in shares) 367,571.000 411,939.000 433,726  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]        
Options outstanding, weighted average exercise price (in dollars per share) $ 9.12 $ 8.94 $ 8.07 $ 8.12
Granted, weighted average exercise price (in dollars per share)   19.64    
Exercised, weighted average exercise price (in dollars per share) 7.00 6.77 8.25  
Forfeited, weighted average exercise price (in dollars per share) $ 19.83 $ 19.58 $ 17.10  
Unvested [Member] | Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]        
Options outstanding, beginning of period (in shares) 37,829 40,810 73,449  
Granted (in shares)   28,499    
Vested (in shares) (17,417) (28,678) (30,379)  
Forfeited (in shares) (1,412) (2,802) (2,260)  
Options outstanding, end of period (in shares) 19,000 37,829 40,810  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]        
Options outstanding, weighted average exercise price (in dollars per share) $ 5.89 $ 8.86 $ 7.39 $ 7.19
Granted, weighted average exercise price (in dollars per share)   19.64    
Vested, weighted average exercise price (in dollars per share) 6.93 6.93 6.93  
Forfeited, weighted average exercise price (in dollars per share) $ 19.83 $ 7.53 $ 7.53