Note 4 - Other Accrued Liabilities - Other Accrued Liabilities (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Insurance	$ 363,000	$ 591,000
Professional services	174,000	92,000
Operating costs	620,000	539,000
Other	321,000	322,000
Total other accrued liabilities	$ 1,478,000	$ 1,544,000