Note 5 - Stock-Based Compensation (Details Textual) - shares shares in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022	Jun. 30, 2021
Share-Based Payment Arrangement, Nonemployee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period (in shares)	15
Share-Based Payment Arrangement, Employee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period (in shares)	162
Restricted Stock [Member] | Share-Based Payment Arrangement, Nonemployee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period (in shares)		25	64