Note 4 - Basic and Diluted Net Income (Loss) Per Share - Basic and Diluted Weighted Average Common Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Weighted average common shares outstanding, basic (in shares)	5,542	5,526	5,542	5,522
Dilutive common equivalent shares (in shares)	84		72
Weighted average common shares outstanding, diluted (in shares)	5,626	5,526	5,614	5,522