Note 6 - Employee Benefit Plans - Benefit Obligation, Fair Value of Plan Assets, Funded Status and Liability of Swiss Plan (Details) - Swiss Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2023	Dec. 31, 2022	Dec. 25, 2021
Benefit obligation at beginning of year	$ (21,628)	$ (28,765)
Service cost	(551)	(954)	$ (1,223)
Interest cost	(510)	(56)	(61)
Actuarial (gain) loss	(1,391)	6,043
Participant contributions	(1,153)	(1,459)
Benefits paid	385	378
Plan change	0	397
Settlements	2,177	2,426
Foreign currency exchange adjustment	(2,213)	362
Benefit obligation at end of year	(24,884)	(21,628)	(28,765)
Fair value of plan assets at beginning of year	18,411	18,919
Return on assets, net of actuarial loss	52	119
Employer contributions	860	831
Participant contributions	1,153	1,459
Benefits paid	(385)	(378)
Settlements	(2,177)	(2,426)
Foreign currency exchange adjustment	1,786	(113)
Fair value of plan assets at end of year	19,700	18,411	$ 18,919
Net liability at end of year	$ (5,184)	$ (3,217)