Note 4 - Stock-based Compensation (Details Textual) shares in Thousands	3 Months Ended		15 Months Ended
	Mar. 31, 2023 USD ($) shares	Mar. 31, 2022 USD ($) shares	Mar. 31, 2023 USD ($) shares
Number of Stock-based Compensation Plans in Effect	2		2
Share-Based Payment Arrangement, Expense | $	$ 0	$ 10,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $	$ 0		$ 0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares) | shares		0	0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Expirations in Period (in shares) | shares	0