NATURE OF OPERATIONS (Details)				3 Months Ended		6 Months Ended
	Feb. 10, 2023	Mar. 31, 2022 USD ($)	Mar. 15, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)	Jan. 12, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of reportable segments | segment						1
Reverse stock split ratio	0.0556
Net loss				$ (10,058,000)	$ (8,476,000)	$ (15,680,000)	$ (3,806,000)
Cash used in operations						(15,052,000)	(17,264,000)
Cash and investments				20,701,000	$ 42,814,000	20,701,000	$ 42,814,000		$ 30,975,000	$ 42,855,000
Accumulated deficit				(678,564,000)		(678,564,000)			(662,735,000)
Additional paid-in capital				695,836,000		695,836,000			$ 693,937,000
Debt outstanding				0		0
Sale of stock, public float threshold				$ 75,000,000		$ 75,000,000
Lincoln Park Equity Purchase Agreement
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Consideration receivable on transaction		$ 30,000,000	$ 30,000,000
Term of equity purchase agreement		36 months	36 months
MST Franchise | Discontinued Operations, Disposed of by Sale
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Additional paid-in capital								$ 5,000,000