Note 6 - Employee Benefit Plans - Reported Share-based Compensation in Consolidated Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Share-based compensation of continuing operations	$ 14,148	$ 10,053	$ 7,007
Income tax benefit	(587)	(993)	(530)
Total share-based compensation, net of tax	13,561	9,060	6,477
Cost of Sales [Member]
Share-based compensation of continuing operations	736	546	423
Research and Development Expense [Member]
Share-based compensation of continuing operations	2,994	1,717	1,054
Selling, General and Administrative Expenses [Member]
Share-based compensation of continuing operations	$ 10,418	$ 7,790	$ 5,530

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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