Note 2 - Certain Significant Estimates - Product Warranty (Details) - SEC Schedule, 12-09, Reserve, Warranty [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Beginning balance	$ 962	$ 688	$ 702
Additions	2,487	1,648	1,736
Deductions	(2,330)	(1,374)	(1,750)
Ending balance	$ 1,119	$ 962	$ 688