Note 10 - Stock Repurchase Program - Schedule of Stock Purchases (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended																23 Months Ended	51 Months Ended
	Apr. 30, 2019		Apr. 30, 2018	[3]	Jul. 31, 2020	[1]	Apr. 30, 2020	[1]	Jan. 31, 2020	[1]	Oct. 31, 2019		Jul. 31, 2019	[1]	Apr. 30, 2019	[1]	Jan. 31, 2019	[1]	Oct. 31, 2018	[1]	Mar. 31, 2018	Jul. 31, 2020		Dec. 31, 2016
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 94	[1]			$ 2,911		$ 3,019		$ 3,019		$ 3,206	[1]	$ 1,526		$ 94		$ 317		$ 381		$ 275	$ 2,911	[1]	$ 500
Number of Shares Purchased (in shares)					212,000		25		267,468		206,050	[1]	120,821		580,705		186,727		480,805		878,814	2,933,415
Average Price Paid per Share (in dollars per share)					$ 0.51		$ 0.41		$ 0.70		$ 0.46	[1]	$ 0.35		$ 0.38		$ 0.34		$ 0.30		$ 0.26	$ 0.37
Number of Shares Purchased as Part of Publicly Announced Plans or Programs (in shares)					212,000		25		267,468		206,050	[1]	120,821		580,705		186,727		480,805		878,814	2,933,415
Increase in program authorization, Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 1,569	[2]	$ 525								$ 3,301	[4]

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

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

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

[4] Board of Directors increased program authorization from $2,225 to $4,000