Note 7 - Stock Plans and Stock Associated with Acquisition - Summary of RSU Activity (Details) - Restricted Stock Units (RSUs) [Member]	9 Months Ended
	Sep. 30, 2016 $ / shares shares
Outstanding at December 31, 2015 (in shares) | shares	155,761
Outstanding at December 31, 2015 (in dollars per share) | $ / shares	$ 4.78
Granted (in shares) | shares	119,655
Granted (in dollars per share) | $ / shares	$ 4.40
Vested (in shares) | shares	(56,728)
Vested (in dollars per share) | $ / shares	$ 4.80
Forfeited or cancelled (in shares) | shares	(6,475)
Forfeited or cancelled (in dollars per share) | $ / shares	$ 4.71
Outstanding at September 30, 2016 (in shares) | shares	212,213
Outstanding at September 30, 2016 (in dollars per share) | $ / shares	$ 4.56