Note 1 - Summary of Significant Accounting Policies (Details Textual)					3 Months Ended			9 Months Ended
		Dec. 28, 2019 USD ($)		Oct. 01, 2019 USD ($)	Sep. 26, 2020 USD ($) shares	Jun. 27, 2020 USD ($)	Sep. 28, 2019 USD ($) shares	Sep. 26, 2020 USD ($) shares	Sep. 28, 2019 USD ($) shares	Jun. 29, 2019 USD ($)	Dec. 30, 2018 USD ($)	Dec. 29, 2018 USD ($)
Gain (Loss) on Disposition of Property Plant Equipment, Total					$ 4,468,000		$ (0)	$ 4,495,000	$ (0)
Number of Operating Segments								4
Number of Reportable Segments								2
Goodwill and Intangible Asset Impairment, Total				$ 0
Amortization of Debt Issuance Costs					300,000		300,000	$ 900,000	800,000
Foreign Currency Transaction Gain (Loss), Realized					$ (1,500,000)		$ 1,600,000	$ (2,500,000)	$ 1,300,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares					109,000		459,000	151,000	487,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		$ 483,072,000			$ 474,609,000	$ 466,758,000	$ 491,397,000	$ 474,609,000	$ 491,397,000	$ 514,449,000		$ 545,944,000
Assets, Total		1,077,710,000	[1]		1,046,353,000			1,046,353,000
Revenue, Remaining Performance Obligation, Amount					8,700,000			8,700,000
Deferred Income		16,100,000			21,900,000			21,900,000
Deferred Profit		7,645,000	[1]		11,859,000			11,859,000
Deferred Profit Long-term		7,200,000			6,800,000			6,800,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total		(34,030,000)	[1]		(21,370,000)			(21,370,000)
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance		$ 42,517,000			11,369,000	18,015,000	$ 62,320,000	$ 11,369,000	$ 62,320,000	$ 75,115,000		111,670,000
Accounting Standards Update 2016-02 [Member]
Assets, Total											$ (500,000)
Liabilities, Total											(600,000)
Accounting Standards Update 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance	[2]											10,352,000
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											$ 10,200,000	$ 10,352,000	[2]
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
Facility in Rosenheim, Germany [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Total					$ 4,500,000
Facility in Penang Malaysia [Member] | Selling, General and Administrative Expenses [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Total						$ 27,000
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 2016-02. Please refer to Note 1 of the Condensed Consolidated Financial Statements for further detail on the adoption of this accounting standard.