6. INCOME TAXES - Statutory income tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
INCOME TAXES
U.S. Federal taxes at statutory rate	$ (2,120)	$ 56	$ (1,282)
State taxes, net of federal benefit		(2)
Deemed repatriation transfer tax			5,117
Deferred tax re-measurement, change in tax rates			1,093
Stock-based compensation	(58)	(124)	(124)
Tax credits	(494)	(536)	(417)
Foreign tax rate differential	593	117	390
Tax exempt interest	(16)	(4)	(8)
Non-deductible expenses and other	38	17	97
Income tax expense (benefit) before change in valuation allowance	(2,057)	(476)	4,866
Valuation allowance	2,304	581	(4,413)
Provision for income taxes	$ 247	$ 105	$ 453