Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Weighted average common shares outstanding - basic (in shares)	10,411,276	10,342,674	10,398,147	10,334,492
Potentially dilutive securities:
Unvested shares of restricted stock and employee stock options (in shares)		27,644	21,767	33,320
Weighted average common shares and common share equivalents outstanding - diluted (in shares)	10,411,276	10,370,318	10,419,914	10,367,812
Average number of potentially dilutive securities excluded from calculation (in shares)	618,071	275,831	423,962	189,794