Geographical information - Long-lived Assets By Geographic Region (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	$ 30,515	$ 33,217
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	23,968	19,086
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	6,547	14,131
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	1,857	1,845
Netherlands
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	4,588	4,778
Estonia
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	0	7,408
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Non-current assets	$ 102	$ 100