Note 6 - Employee Benefit Plans - Reported Share-based Compensation in Consolidated Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Share-based compensation of continuing operations	$ 13,792	$ 14,234	$ 14,148
Income tax benefit	(722)	(963)	(587)
Total share-based compensation, net of tax	13,070	13,271	13,561
Cost of Sales [Member]
Share-based compensation of continuing operations	828	893	736
Research and Development Expense [Member]
Share-based compensation of continuing operations	3,017	3,245	2,994
Selling, General and Administrative Expenses [Member]
Share-based compensation of continuing operations	$ 9,947	$ 10,096	$ 10,418

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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