Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands					3 Months Ended
		Dec. 28, 2019 USD ($)		Oct. 01, 2019 USD ($)	Mar. 28, 2020 USD ($) shares	Mar. 30, 2019 USD ($) shares	Dec. 30, 2018 USD ($)	Dec. 29, 2018 USD ($)
Number of Operating Segments					4
Number of Reportable Segments					2
Goodwill and Intangible Asset Impairment, Total				$ 0
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)					$ 3,949
Amortization of Debt Issuance Costs					300	300
Foreign Currency Transaction Gain (Loss), Realized					$ (400)	$ 200
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares					58,000	393,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		$ 483,072			$ 464,884	$ 528,314		$ 545,944
Assets, Total		1,077,710	[1]		1,072,155
Revenue, Remaining Performance Obligation, Amount					9,600
Deferred Income		16,100			18,000
Deferred Profit		7,645			9,313
Deferred Profit Long-term		7,200			7,100
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total		(34,030)			(34,959)
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		$ 42,517			22,755	$ 96,938		111,670
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	[2]							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							$ 10,200	$ 10,352	[2]
Indefinite-lived In Process Research and Development [Member]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)					$ 3,900
Minimum [Member]
Standard Product Warranty Term (Month)					1 year
Maximum [Member]
Standard Product Warranty Term (Month)					3 years
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
ALBS [Member]
Variable Interest Entity, Ownership Percentage Sold		20.00%

[1] Derived from December 28, 2019 audited financial statements

[2] Cumulative effect of accounting change relates to our adoption of ASU 2014-09.