Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Weighted average common shares outstanding - basic (in shares)	10,252,490	10,411,276	10,236,672	10,398,147
Unvested shares of restricted stock and employee stock options (in shares)	6,427			21,767
Weighted average common shares and common share equivalents outstanding - diluted (in shares)	10,258,917	10,411,276	10,236,672	10,419,914
Average number of potentially dilutive securities excluded from calculation (in shares)	711,499	618,071	719,832	423,962