Note 6 - Net Income Per Share - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income (loss)	$ (2,082)	$ 590	$ (4,602)	$ 1,297
Basic weighted-average common shares outstanding (in shares)	32,184	32,078	32,105	32,060
Effect of dilutive options and restricted stock (in shares)		891		1,257
Diluted weighted average shares outstanding (in shares)	32,184	32,969	32,105	33,317
Net income (loss) per share - Basic (in dollars per share)	$ (0.06)	$ 0.02	$ (0.14)	$ 0.04
Net income (loss) per share - Diluted (in dollars per share)	$ (0.06)	$ 0.02	$ (0.14)	$ 0.04