Note 6 - Employee Benefit Plans (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 25, 2021	Dec. 26, 2020	May 08, 2019
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	8.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 2,400	$ 2,400	$ 2,300
Deferred Compensation Liability, Current, Total	1,100	1,600
Cash Surrender Value of Life Insurance	$ 1,400	$ 1,800
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	0	0	0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 200	$ 8,400	$ 1,300
Restricted Stock Units (RSUs) [Member] | Vesting Over One Year Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	1 year
Restricted Stock Units (RSUs) [Member] | Vesting Over Two Year Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	2 years
Restricted Stock Units (RSUs) [Member] | Vesting Over Four Year Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	4 years
Equity Based Performance Stock Units Granted in 2020, 2019, 2018, and 2017 [Member] | Vest on the Third Anniversary of Awards Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	100.00%
Unvested Restricted Stock Units [Member]
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 21,600
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	2 years 3 months 18 days
Minimum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Shares Available for Issue	0.00%
Maximum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Shares Available for Issue	200.00%
Employee Stock Purchase Plan [Member]
Employee Stock Purchase Plan, Shares Reserved for Future Issuance (in shares)		2,650,000
Percentage of Fair Value to Determine Price of Common Stock		85.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)	160,855	161,351	242,633
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)	346,498
Equity Incentive Plan 2005 [Member]
Percentage of Fair Value to Determine Price of Common Stock				100.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)	914,705
Equity Incentive Plan 2005 [Member] | Share-Based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Equity Incentive Plan 2005 [Member] | Minimum [Member] | Share-Based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	1 year
Equity Incentive Plan 2005 [Member] | Maximum [Member] | Share-Based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	4 years
Postretirement Health Coverage [Member]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ 382	$ 241
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	100
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	100
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	100
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	100
Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years	600
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	$ 100		$ 100
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.90%	2.50%	2.10%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.40%
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 100
Swiss Plan [Member]
Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Tax	6,800	$ 900
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	6,043	1,179
Defined Benefit Plan, Expected Future Employee and Employer Contributions, Next Twelve Months	900
Defined Benefit Plan, Expected Future Benefit Payment, Year One	1,200
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	1,300
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	1,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	1,200
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	1,300
Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years	6,800
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	$ 395	$ 1,228	$ 1,469
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.30%	0.20%
Swiss Plan [Member] | Debt Securities and Cash [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	54.00%
Swiss Plan [Member] | Real Estate Investments [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	23.00%
Swiss Plan [Member] | Alternative Investments [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	13.00%
Swiss Plan [Member] | Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%
Pre Age 65 Plan [Member] | Postretirement Health Coverage [Member]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	6.80%
Defined Benefit Plan, Health Care Cost Trend Rate, Annual Rate of Change	(0.27%)
Post Age 65 Plan [Member] | Postretirement Health Coverage [Member]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7.20%
Defined Benefit Plan, Health Care Cost Trend Rate, Annual Rate of Change	(0.31%)