Note 10 - Stockholders' Equity and Stock-based Compensation - Restricted Stock and Restricted Stock Units Activity (Details) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2021
Balance (in shares)	647,483	407,967
Share-based Payment Arrangement, Option [Member]
Balance (in shares)		533,320
Options Granted (in shares)		0
Options Exercises (in shares)		0
Options Cancelled/forfeited (in shares)		(125,353)
Balance (in shares)		407,967
Restricted Stock and Restricted Stock Units [Member]
Balance (in shares)		732,707
Equity instruments other than options, authorized (in shares)		23,533
Equity instruments other than options, granted (in shares)		966,000
Equity instruments other than options, vested (in shares)		(473,204)
Equity instruments other than options, cancelled/forfeited (in shares)		(66,944)
Balance (in shares)	873,371	1,182,092
Stock Appreciation Rights (SARs) [Member]
Balance (in shares)		754,582
Options Granted (in shares)		0
Options Exercises (in shares)		(5,000)
Options Cancelled/forfeited (in shares)		(86,991)
Balance (in shares)	906,850	662,591