Note 4 - Other Accrued Liabilities - Other Accrued Liabilities (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Insurance	$ 135,000	$ 591,000
Professional services	323,000	92,000
Operating costs	624,000	539,000
Other	314,000	322,000
Total other accrued liabilities	$ 1,396,000	$ 1,544,000