Note 10 - Stock Incentive Plans - Share-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total compensation cost for share-based payments	$ 325	$ (29)	$ 567	$ 581
Weighted average grant-date fair value of equity instruments granted (per share) (in dollars per share)	$ 1.75	$ 2.20	$ 1.76	$ 1.81
Total fair value of shares vested during the period		$ 140	$ 1,524	$ 2,286
Unamortized share-based payments			$ 1,315	$ 807
Weighted average period to be recognized as expense (Year)			1 year 109 days	1 year 109 days