Note 10 - Stock Repurchase Program - Schedule of Stock Purchases (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended														15 Months Ended	39 Months Ended
	Apr. 30, 2019		Apr. 30, 2018		Jul. 31, 2019	[1]	Apr. 30, 2019	[1]	Jan. 31, 2019	[1]	Oct. 31, 2018	[1]	Jul. 31, 2018	[1]	Apr. 30, 2018	[1]	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Jul. 31, 2019		Dec. 31, 2016
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 94	[1]	$ 281	[1]	$ 1,526		$ 94		$ 317		$ 381		$ 525		$ 281		$ 326	$ 465	$ 468	$ 1,526	[1]	$ 500
Stock repurchase (in shares)					120,821		580,705		186,727		480,805		25,277		178,526		536,058	8,607	130,346	2,247,872
Average Price Paid per Share (in dollars per share)					$ 0.35		$ 0.38		$ 0.34		$ 0.30		$ 0.26		$ 0.25		$ 0.26	$ 0.30	$ 0.25	$ 0.31
Number of Shares Purchased as Part of Publicly Announced Plans or Programs (in shares)					120,821		580,705		186,727		480,805		25,277		178,526		536,058	8,607	130,346	2,247,872
Number of Shares Purchased (in shares)					120,821		580,705		186,727		480,805		25,277		178,526		536,058	8,607	130,346	2,247,872
Increase in program authorization, Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 1,569	[2]	$ 531	[3]

[1] These shares of common stock purchased were purchased through a private transaction.

[2] Board of Directors increased program authorization from $750 to $2,225

[3] Board of Directors increased program authorization from $500 to $750