Note 12 - Business Divestitures and Discontinued Operations (Details Textual) $ in Thousands			3 Months Ended				6 Months Ended	9 Months Ended
		Jun. 24, 2021 USD ($)	Sep. 28, 2021 USD ($)	Sep. 25, 2021 USD ($)	Sep. 25, 2021	Sep. 26, 2020 USD ($)	Jun. 24, 2021 USD ($)	Sep. 25, 2021 USD ($)	Sep. 26, 2020 USD ($)
Gain (Loss) on Disposition of Business	[1]			$ 90		$ (0)		$ 75,754	$ (0)
Number of Reportable Segments					1		2
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | PCB Test Equipment [Member]
Proceeds from Sales of Business, Affiliate and Productive Assets		$ 125,100
Gain (Loss) on Disposition of Business		75,800	$ 100
Disposal Group, Including Discontinued Operation, Assets, Total		43,400					$ 43,400
Disposal Group, Including Discontinued Operation, Goodwill		21,900					21,900
Disposal Group, Including Discontinued Operation, Intangible Assets		$ 10,000					$ 10,000

[1] On June 24, 2021 we completed the divestment of our PCB Test business. The divestment of this business did not qualify for presentation as discontinued operations and the results of the PCB Test business are included in continuing operations for all periods presented. See Note 12, “Business Divestitures and Discontinued Operations” for additional information on this transaction and financial statement presentation.