Note 4 - Other Accrued Liabilities - Other Accrued Liabilities (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Professional services	$ 769,000	$ 472,000
Operating costs	489,000	450,000
Other	326,000	304,000
Total other accrued liabilities	$ 1,584,000	$ 1,226,000