Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Weighted average common shares outstanding - basic (in shares)	10,329,449	10,220,853
Unvested shares of restricted stock and employee stock options (in shares)	196,377
Weighted average common shares and common share equivalents outstanding - diluted (in shares)	10,525,826	10,220,853
Average number of potentially dilutive securities excluded from calculation (in shares)	347,068	685,667