12. SEGMENT AND GEOGRAPHIC INFORMATION - Revenue (Details) $ in Thousands	3 Months Ended
	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)
Net revenues by geographic area
Net revenues	$ 6,621	$ 13,019
Number of reporting units | segment	1
United States
Net revenues by geographic area
Net revenues	$ 2,467	4,606
China
Net revenues by geographic area
Net revenues	637	1,233
Singapore
Net revenues by geographic area
Net revenues	1,239	3,542
Netherlands
Net revenues by geographic area
Net revenues	1,534	1,393
Germany
Net revenues by geographic area
Net revenues	478	1,897
Rest of the world
Net revenues by geographic area
Net revenues	$ 266	$ 348