Note 6 - Employee Benefit Plans - Net Periodic Benefit Cost of Swiss Plan (Details) - Swiss Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 25, 2021	Dec. 26, 2020
Service cost	$ 954	$ 1,223	$ 1,310
Interest cost	56	61	67
Expected return on assets	(128)	(128)	(200)
Settlements	(487)	72	292
Net periodic costs	$ 395	$ 1,228	$ 1,469