Note 6 - Employee Benefit Plans - Net Periodic Benefit Cost of Swiss Plan (Details) - Swiss Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Service cost	$ 925	$ 907	$ 868
Interest cost	207	198	245
Expected return on assets	(124)	(119)	(147)
Net periodic costs	$ 1,008	$ 986	$ 966