Note 10 - Stock Repurchase Program - Schedule of Stock Purchases (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended						3 Months Ended																21 Months Ended	45 Months Ended
	Oct. 31, 2019		Apr. 30, 2019		Apr. 30, 2018		Jan. 31, 2020	[1]	Oct. 31, 2019	[1]	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	Jan. 31, 2020		Dec. 31, 2016
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 3,206	[1]	$ 94	[1]	$ 281	[1]	$ 3,019		$ 3,206		$ 1,526		$ 94		$ 317		$ 381		$ 525		$ 281		$ 326	$ 3,019	[1]	$ 500
Number of Shares Purchased (in shares)							267,468		206,050		120,821		580,705		186,727		480,805		25,277		178,526		675,011	2,721,390
Average Price Paid per Share (in dollars per share)							$ 0.70		$ 0.46		$ 0.35		$ 0.38		$ 0.34		$ 0.30		$ 0.26		$ 0.25		$ 0.26	$ 0.36
Number of Shares Purchased as Part of Publicly Announced Plans or Programs (in shares)							267,468		206,050		120,821		580,705		186,727		480,805		25,277		178,526		675,011	2,721,390
Increase in program authorization, Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 3,301	[2]	$ 1,569	[3]	$ 531	[4]

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

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

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

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