Net loss per share (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Numerator:        
Net loss attributable to common stockholders $ (16,189) $ (7,673) $ (36,836) $ (24,178)
Denominator:        
Weighted average common shares outstanding, basic and diluted (in shares) 34,877,944 31,577,313 32,742,148 20,433,580
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share) $ (0.46) $ (0.24) $ (1.13) $ (1.18)