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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)

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