6. INCOME TAXES - Tax Cuts and Jobs Act (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Corporate income tax rate	35.00%	21.00%	21.00%	21.00%
Tax expense, one-time transition tax				$ 367,000
Cash, cash equivalents and short-term and long-term investments		$ 70,700,000
Possible reduction in uncertain tax benefits		0
Valuation allowance		9,389,000	$ 6,700,000
Federal
Net operating loss carryforwards for income tax purposes		5,300,000
Tax credit carryforwards for income tax purposes		2,600,000
State
Net operating loss carryforwards for income tax purposes		1,900,000
Tax credit carryforwards for income tax purposes		$ 3,700,000