Note 9 - Stock-based Compensation - Stock Option Activity (Details)	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Options outstanding (in shares) | shares	19,800
Options outstanding (in dollars per share) | $ / shares	$ 4.37
Granted (in shares) | shares	96,000
Granted (in dollars per share) | $ / shares	$ 6.35
Options outstanding (in shares) | shares	115,800
Options outstanding (in dollars per share) | $ / shares	$ 6.01