Note 3 - Stock-based Compensation (Details Textual) - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares, Ending Balance (in shares)	0	0
Share-based Payment Arrangement, Expense	$ (408,000)	$ 90,000
Deferred Compensation Share-based Arrangements, Liability, Current and Noncurrent	287,000	$ 236,000
Restricted Stock [Member]
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 219,000
Restricted Stock [Member] | Forecast [Member]
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount			$ 4,000	$ 34,000	$ 88,000	$ 94,000