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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, 2019 | Dec. 31, 2018 | Jan. 01, 2018
Research and Development Expense, Total |  | $ 26,925 | $ 29,487 |
Foreign Currency Transaction Gain (Loss), before Tax, Total |  | $ 110 | $ 2,663 |
Intangible Assets, Percent of Total Assets |  | 15.40% | 14.10% |
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 |  | 0 | 0 |
Operating Lease, Right-of-Use Asset |  | $ 18,504 |  |
Operating Lease, Liability, Total |  | 19,128 |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | 3,497 |
Retained Earnings [Member] |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  | $ 463 | $ 3,497 |
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 |  |  |
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member] |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  | $ 3,400
Minimum [Member] |  |  |  |
Standard Product Warranty, Period |  | 1 year |  |
Finite-Lived Intangible Asset, Useful Life |  | 1 year |  |
Minimum [Member] | Building and Building Improvements [Member] |  |  |  |
Property, Plant and Equipment, Useful Life |  | 2 years |  |
Minimum [Member] | Machinery and Equipment [Member] |  |  |  |
Property, Plant and Equipment, Useful Life |  | 3 years |  |
Maximum [Member] |  |  |  |
Standard Product Warranty, Period |  | 3 years |  |
Finite-Lived Intangible Asset, Useful Life |  | 16 years |  |
Maximum [Member] | Building and Building Improvements [Member] |  |  |  |
Property, Plant and Equipment, Useful Life |  | 33 years |  |
Maximum [Member] | Machinery and Equipment [Member] |  |  |  |
Property, Plant and Equipment, Useful Life |  | 15 years |  |

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