Note 12 - Stock Repurchase Program - Schedule of Stock Purchases (Details) - USD ($)	3 Months Ended																60 Months Ended	84 Months Ended
	Apr. 30, 2023		Jan. 31, 2023		Oct. 31, 2022		Jul. 31, 2022	[1]	Apr. 30, 2022	[1]	Jan. 31, 2022	[1]	Oct. 31, 2021	[1]	Jul. 31, 2021	[1]	Apr. 30, 2021	Apr. 30, 2023		Dec. 31, 2016
Approximate Dollar Value of Shares That May Yet Be Purchased Under the Plan or Programs	$ 2,594	[1]	$ 2,595	[1]	$ 2,653,000	[1]	$ 2,653,000		$ 2,655,000		$ 2,819,000		$ 2,819,000		$ 2,823,000		$ 2,823,000	$ 2,594	[1]	$ 4,000
Number of Shares Purchased (in shares)	2,000		85,307		150		1,639		180,503		0		6,290		0		3,103,633	3,379,522
Average Price Paid per Share (in dollars per share)	$ 0.68	[1]	$ 0.68	[1]	$ 0.70	[1]	$ 0.84		$ 0.91		$ 0		$ 0.62		$ 0		$ 0.38	$ 0.42
Number of Shares Purchased as Part of Publicly Announced Plans or Programs (in shares)	2,000	[1]	85,307	[1]	150	[1]	1,639		180,503		0		6,290		0		3,103,633	3,379,522

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