Note 6 - 2021 At-the-market Offering (Details Textual) - USD ($) shares in Thousands	1 Months Ended	3 Months Ended	5 Months Ended	9 Months Ended
	Nov. 05, 2021	Sep. 25, 2021	Sep. 25, 2021	Sep. 25, 2021	Sep. 26, 2020	Apr. 26, 2021
Proceeds from Issuance of Common Stock				$ 3,422,370	$ 0
At-the-market Offering [Member]
Stock Offering Agreement, Maximum Offering, Amount						$ 25,000,000.0
Stock Offering Agreement, Commission, Percent						3.00%
Stock Issued During Period, Shares, New Issues (in shares)		48	527
Proceeds from Issuance of Common Stock		$ 295,000	$ 3,700,000
At-the-market Offering [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)	0