Note 6 - Employee Benefit Plans - Net Periodic Benefit Cost of Swiss Plan (Details) - Swiss Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Service cost	$ 1,223	$ 1,310	$ 920
Interest cost	61	67	267
Expected return on assets	(128)	(200)	(168)
Settlements	72	292	0
Net periodic costs	$ 1,228	$ 1,469	$ 1,019