Net income per share - Reconciliation of Numerator and Denominator in Basic and Diluted Net Income (Loss) Per Common Share Computations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net income	$ 1,512	$ 3,706
Denominator:
Weighted average common shares outstanding - basic (in shares)	48,924,454	48,345,942
Dilutive common equivalent shares from equity awards (in shares)	2,015,484	1,971,146
Weighted average common shares outstanding - diluted (in shares)	50,939,938	50,317,088
Net income per share:
Basic (in USD per share)	$ 0.03	$ 0.08
Diluted (in USD per share)	$ 0.03	$ 0.07
Anti-dilutive securities excluded from diluted EPS:
Weighted average anti-dilutive shares from outstanding equity awards excluded from diluted earnings per share (in shares)	2,567,951	2,891,303