Note 11 - Stock Repurchase Program - Schedule of Stock Purchases (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												48 Months Ended	72 Months Ended
	Apr. 30, 2022	Oct. 31, 2021	Jul. 31, 2021	[1]	Apr. 30, 2021	[1]	Jan. 31, 2021	[1]	Oct. 31, 2020	[1]	Jul. 31, 2020	[1]	Apr. 30, 2020	Apr. 30, 2022	Jan. 31, 2022	Dec. 31, 2016
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 2,655	$ 2,819	$ 2,823		$ 2,823		$ 2,835		$ 2,835		$ 2,911		$ 3,019	$ 2,655	$ 2,819	$ 4,000
Number of Shares Purchased (in shares)	180,503	6,290	0		17,303		0		152,915		212,000		2,721,415	3,290,426
Average Price Paid per Share (in dollars per share)	$ 0.91	$ 0.62			$ 0.65		$ 0		$ 0.50		$ 0.51		$ 0.36	$ 0.41
Number of Shares Purchased as Part of Publicly Announced Plans or Programs (in shares)	180,503	6,290	0		17,303		0		152,915		212,000		2,721,415	3,290,426

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