Note 2 - Goodwill and Purchased Intangible Assets - Changes in Carrying Value of Goodwill (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 25, 2021
Beginning balance		$ 219,791	$ 252,304
Sale of PCB Test Business (1)	[1]		(21,899)
Impact of currency exchange		(6,252)	(10,614)
Ending balance		213,539	219,791
Semiconductor Test and Inspection [Member]
Beginning balance		219,791	230,724
Sale of PCB Test Business (1)	[1]		0
Impact of currency exchange		(6,252)	(10,933)
Ending balance		213,539	219,791
PCB Test [Member]
Beginning balance		0	21,580
Sale of PCB Test Business (1)	[1]		(21,899)
Impact of currency exchange		0	319
Ending balance		$ 0	$ 0

[1] On June 24, 2021, we completed the sale of our PCB Test business. See Note 14, “Business Divestitures and Discontinued Operations” for additional information.