Note 4 - Basic and Diluted Net Income Per Share - Basic and Diluted Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Weighted average common shares outstanding, basic (in shares)	5,507	5,491	5,500	5,476
Dilutive common equivalent shares (in shares)	48	73	52	64
Weighted average common shares outstanding, diluted (in shares)	5,555	5,564	5,552	5,540