Note 1 - Description of Business and Summary of Significant Accounting Policies (Details Textual) - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
Jan. 01, 2019	Dec. 31, 2020	Dec. 31, 2019
Cost of Goods and Services Sold, Total		$ 346,041	$ 382,439
Nonoperating Income (Expense), Total		(1,785)	(259)
Selling, General and Administrative Expense, Total		78,704	77,416
Foreign Currency Transaction Gain (Loss), before Tax, Total		$ (2,168)	$ 110
Intangible Assets, Percent of Total Assets		14.50%	15.40%
Excessive Dividend Rate of Class B Over Class A		5.00%
Excessive Undistributed Earnings Allocation Rate of Class B Over Class A		5.00%
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)		0	0
Research and Development Expense, Total		$ 23,611	$ 26,925
Operating Lease, Right-of-Use Asset		14,217	$ 18,504
Operating Lease, Liability, Total		$ 14,655
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset	$ 20,700
Operating Lease, Liability, Total	21,000
Accounting Standards Update 2018-02 [Member]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	$ 500
Minimum [Member]
Standard Product Warranty, Period (Year)		1 year
Finite-Lived Intangible Asset, Useful Life (Year)		1 year
Minimum [Member] \| Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life (Year)		1 year
Minimum [Member] \| Machinery and Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)		2 years
Maximum [Member]
Standard Product Warranty, Period (Year)		3 years
Finite-Lived Intangible Asset, Useful Life (Year)		16 years	16 years
Maximum [Member] \| Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life (Year)		33 years
Maximum [Member] \| Machinery and Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)		15 years
Revision of Prior Period, Adjustment [Member]
Cost of Goods and Services Sold, Total		$ (1,100)
Nonoperating Income (Expense), Total		$ 1,100	$ 2,100
Selling, General and Administrative Expense, Total			$ (2,100)

Dividend rate of class B in excess of dividend rate of class A.

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Undistributed earnings allocated to class B of common stock in excess of earnings allocated to class A.

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The standard product warranty period in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act.

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