Note 4 - Basic and Diluted Net Income Per Share - Basic and Diluted Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted average common shares outstanding, basic (in shares)	5,502	5,477	5,497	5,469
Dilutive common equivalent shares (in shares)	52	64	55	64
Weighted average common shares outstanding, diluted (in shares)	5,554	5,541	5,552	5,533