Note 6 - 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. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Change in projected benefit obligation:
Benefit obligation at beginning of year	$ 26,027	$ 23,850
Service cost	(856)	(749)	$ (841)
Interest cost	(311)	(491)	(398)
Actuarial gain (loss)	(660)	(3,649)
Participant contributions	(672)	(728)
Benefits paid	296	$ 998
Plan change	558
Settlements	2,199
Foreign currency exchange adjustment	(10)	$ 2,442
Benefit obligation at end of year	25,483	26,027	23,850
Change in plan assets:
Fair value of plan assets at beginning of year	15,603	16,083
Return on assets, net of actuarial loss	277	652
Employer contributions	672	728
Participant contributions	672	728
Benefits paid	(296)	$ (998)
Settlements	(2,199)
Foreign currency exchange adjustment	(13)	$ (1,590)
Fair value of plan assets at end of year	14,716	15,603	$ 16,083
Net liability at end of year	$ (10,767)	$ (10,424)