INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended			24 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2019
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ 1,200,000	$ 19,700,000	$ (18,400,000)
Income (Loss) from Continuing Operations before Income Taxes, Foreign	1,700,000	1,400,000	300,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%
Deferred Tax Assets, Valuation Allowance, Total	59,215,000	51,586,000		$ 59,215,000
Deferred Tax Assets, Net, Total	17,000	17,000		17,000
Unrecognized tax benefits related to income tax penalties and interest accrued in long-term liabilities	700,000	700,000	800,000	700,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense (Reversal)	(61,000)	(89,000)	33,000
Unrecognized Tax Benefits, Ending Balance	15,109,000	14,743,000	$ 14,300,000	15,109,000	$ 13,615,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	2,000,000.0			2,000,000.0
Unrecognized tax benefits including income tax penalties and interest accrued in long term liabilities	2,600,000			2,600,000
Unrecognized Tax Benefits In Deferred Tax Asset Subject To Full Valuation Allowance	13,200,000			13,200,000
California R&D Tax Credits [Member]
Deferred Tax Assets, Valuation Allowance, Total	59,200,000	$ 51,600,000		59,200,000
U.S.
Tax Credit Carryforward, Amount	21,800,000			21,800,000
U.S. | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards, Total	9,900,000			9,900,000
U.S. | California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	11,200,000			11,200,000
State and Local
Tax Credit Carryforward, Amount	$ 22,800,000			$ 22,800,000