XML 233 R85.htm IDEA: XBRL DOCUMENT v3.20.2
Stock-based compensation plan - SARs, Narrative (Details) - SARs - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting percentage 25.00%    
Award expiration period 6 years    
Annual total shareholder return percentage (in excess of) 10.00%    
Estimated forfeiture rate 5.00%    
Weighted-average grant-date fair value (in dollars per share) $ 0.18 $ 0.23 $ 0.07
Total intrinsic value of awards exercised $ 1,010 $ 580 $ 140
Unrecognized compensation cost $ 1,580    
Expected period for recognition of unvested awards 4 years 3 months 18 days