Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands			12 Months Ended
		Oct. 01, 2020 USD ($)	Dec. 26, 2020 USD ($) shares	Dec. 28, 2019 USD ($) shares	Dec. 29, 2018 USD ($) shares		Dec. 30, 2018 USD ($)	Dec. 30, 2017 USD ($)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares			113,000	422,000	146,000
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense			$ 8,100	$ 4,800	$ 10,800
Gain (Loss) on Disposition of Property Plant Equipment, Total			4,495	(0)	(0)
Depreciation, Total			14,000	19,300	8,800
Capitalized Computer Software, Gross			13,500	10,300
Capitalized Computer Software, Amortization			$ 1,191	0	0
Number of Operating Segments			4
Number of Reportable Segments			2
Goodwill and Intangible Asset Impairment, Total		$ 0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance			$ 512,288	483,072	545,944			$ 289,091
Assets, Total			1,090,346	1,077,710	1,134,002
Revenue, Remaining Performance Obligation, Amount			17,100	16,100
Deferred Revenue, Total			17,100	16,100
Deferred Profit			8,671	7,645
Deferred Profit Long-term			6,700	7,200
Amortization of Debt Issuance Costs			1,200	1,100
Foreign Currency Transaction Gain (Loss), Realized			(3,200)		1,700
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total			(4,326)	(34,030)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax			27,300	(7,500)
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance			$ 26,230	42,517	111,670			$ 150,726
Accounting Standards Update 2016-02 [Member]
Assets, Total							$ (500)
Liabilities, Total							(600)
Accounting Standards Update 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance	[1]				10,352
Accounting Standards Update 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance					10,352	[1]	$ 10,200
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			7 years
Xcerra [Member]
Capital Leased Assets, Gross, Total				2,600
Minimum [Member]
Standard Product Warranty Term (Month)			12 months
Maximum [Member]
Standard Product Warranty Term (Month)			36 months
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			30 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			40 years
Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			5 years
Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			15 years
Machinery, Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)			3 years
Machinery, Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)			10 years
Xcerra [Member]
Inventory Write-down			$ 2,100	$ 700	$ 9,400
ALBS [Member]
Variable Interest Entity, Ownership Percentage Sold				20.00%
Gain (Loss) on Disposition of Business				$ 100

[1] Cumulative effect of accounting change relates to our adoption of ASU 2016-02. Please refer to Note 1 of the Consolidated Financial Statements for further detail on the adoption of this accounting standard.