Note 12 - Equity Incentive Plan - Granted and Exercised Stock-based Compensation Awards (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Option [Member]
Grants (in shares)	85,345	87,250	402,558	218,867
Exercises (in shares)	0	488,586	2,146	511,486
Forfeitures (in shares)	32,629	42,566	86,732	81,638
Expirations (in shares)	3,083	25,697	3,646	44,829
Restricted Stock Units (RSUs) [Member]
Grants (in shares)	34,697	9,000	218,804	185,507
Forfeitures (in shares)	17,937	7,500	90,103	19,100
Performance Restricted Stock Units [Member]
Grants (in shares)	16,077	9,000	162,297	123,500
Forfeitures (in shares)	19,000	4,500	90,000	13,500
Total Shareholder Return ("TSRs") Options [Member]
Grants (in shares)	0	0	104,638	0
Restricted Stock [Member]
Forfeitures (in shares)	0	1,975	8,574	12,533