Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Weighted average common shares outstanding–basic (in shares)	10,617,271	10,329,449
Unvested shares of restricted stock and employee stock options (in shares)	225,321	196,377
Weighted average common shares and common share equivalents outstanding – diluted (in shares)	10,842,592	10,525,826
Average number of potentially dilutive securities excluded from calculation (in shares)	318,574	347,068