13. SEGMENT AND GEOGRAPHIC INFORMATION - Revenue (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Net revenues by geographic area
Net revenues	$ 8,535	$ 10,049	$ 11,740	$ 13,019	$ 12,686	$ 14,702	$ 12,832	$ 11,266	$ 43,343	$ 51,486	$ 42,643
Number of reporting units | segment									1
United States
Net revenues by geographic area
Net revenues									$ 17,505	19,327	20,690
China
Net revenues by geographic area
Net revenues									6,079	4,458	5,520
Singapore
Net revenues by geographic area
Net revenues									6,556	7,592	6,878
Netherlands
Net revenues by geographic area
Net revenues									5,463	11,093	4,375
Germany
Net revenues by geographic area
Net revenues									6,604	7,478	3,769
Rest of the world
Net revenues by geographic area
Net revenues									$ 1,136	$ 1,538	$ 1,411