Note 16 - Stock-Based Compensation - Stock Purchase Plan (Details) - Employee Stock Purchase Plan - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares granted (in shares)	28,396	38,738	29,882
Issuance of shares of common stock as a result of stock purchased under the Employee Stock Purchase Plan (in shares)	30,543	37,114	28,775
Weighted average fair value per share granted (in dollars per share)	$ 7.67	$ 6.03	$ 4.81