Geographical information - Revenue by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Revenue, Major Customer [Line Items]
Total revenue	$ 36,970	$ 47,188
United States
Revenue, Major Customer [Line Items]
Total revenue	34,649	37,611
Foreign
Revenue, Major Customer [Line Items]
Total revenue	$ 2,321	$ 9,577