Note 2 - Summary of Significant Accounting Policies - Basic and Diluted Weighted Average Common Shares Outstanding (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted average common shares outstanding, basic (in shares)	5,480	5,447	5,405
Dilutive common equivalent shares (in shares)	60	28	7
Weighted average common shares outstanding, assuming dilution (in shares)	5,540	5,475	5,412