Note 10 - Segment and Geographic Information - Summary of Current Segments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Net sales		$ 887,214	$ 636,007	$ 583,329
Profit (loss) for reportable segments		141,933	4,474	(42,437)
Gain (Loss) on Disposition of Business	[1]	70,815	(0)	(0)
Interest expense		(6,413)	(13,759)	(20,556)
Interest income		239	224	764
Gain (Loss) on Extinguishment of Debt, Total		(3,411)	268	0
Profit (loss) from continuing operations before taxes		192,344	(13,177)	(72,077)
Total depreciation and amortization		48,568	52,746	58,871
Capital expenditures		12,000	18,660	18,000
Total assets for reportable segments		1,259,044	1,090,346	1,077,710
Discontinued operations		0	0	3,618
Corporate, Non-Segment [Member]
Corporate expenses		(10,819)	(4,384)	(9,848)
Total assets for reportable segments		137,186	55,492	18,398
Semiconductor Test and Inspection [Member]
Net sales		860,454	585,240	540,878
Profit (loss) for reportable segments		138,026	(2,497)	(45,072)
Total depreciation and amortization		48,129	51,548	56,621
Capital expenditures		11,954	18,616	17,831
Total assets for reportable segments		1,121,858	968,028	998,756
PCB Test [Member]
Net sales		26,760	50,767	42,451
Profit (loss) for reportable segments		3,907	6,971	2,635
Total depreciation and amortization		439	1,198	2,250
Capital expenditures		46	44	169
Total assets for reportable segments		0	66,826	56,938
Semiconductor Test and Inspection and PCB Test [Member]
Total assets for reportable segments		$ 1,121,858	$ 1,034,854	$ 1,055,694

[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 14, “Business Divestitures and Discontinued Operations” for additional information on this transaction and financial statement presentation.