Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Weighted average common shares outstanding - basic (in shares)	10,653,268	10,442,916	10,635,270	10,386,183
Unvested shares of restricted stock and employee stock options (in shares)	161,531	322,020	193,426	259,198
Weighted average common shares and common share equivalents outstanding - diluted (in shares)	10,814,799	10,764,936	10,828,696	10,645,381
Average number of potentially dilutive securities excluded from calculation (in shares)	608,322	274,345	477,448	307,069