Note 2 - Income Per Share - Calculation of Net Income (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net income	$ 4,632	$ 2,869	$ 6,141	$ 10,853
Denominator:
Basic weighted average shares outstanding (in shares)	18,288	18,194	18,275	18,177
Effect of dilutive securities:
Equivalent shares issuable upon conversion of unvested restricted stock (in shares)	116	93	91	81
Denominator for diluted earnings per share – adjusted weighted-average shares and assumed conversions (in shares)	18,404	18,287	18,366	18,258
Basic net income per share (in dollars per share)	$ 0.25	$ 0.16	$ 0.34	$ 0.60
Diluted net income per share (in dollars per share)	$ 0.25	$ 0.16	$ 0.33	$ 0.59