Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Weighted average common shares outstanding - basic (in shares)	10,442,916	10,252,490	10,386,183	10,236,672
Unvested shares of restricted stock and employee stock options (in shares)	322,020	6,427	259,198	0
Weighted average common shares and common share equivalents outstanding - diluted (in shares)	10,764,936	10,258,917	10,645,381	10,236,672
Average number of potentially dilutive securities excluded from calculation (in shares)	274,345	711,499	307,069	719,832