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Note 6 - Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value of Senior Notes (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Dec. 30, 2017
--- | --- | ---
Euro Senior Notes, Series A [Member] | Reported Value Measurement [Member] |  |
Senior Notes, Fair Value | $ 144,041 | $ 139,623
Euro Senior Notes, Series A [Member] | Estimate of Fair Value Measurement [Member] |  |
Senior Notes, Fair Value | 142,038 | 138,294
Euro Senior Notes, Series B [Member] | Reported Value Measurement [Member] |  |
Senior Notes, Fair Value | 116,956 | 113,369
Euro Senior Notes, Series B [Member] | Estimate of Fair Value Measurement [Member] |  |
Senior Notes, Fair Value | 113,953 | 111,579
US Senior Notes, Series A Due 2022 [Member] | Reported Value Measurement [Member] |  |
Senior Notes, Fair Value | 25,000 | 25,000
US Senior Notes, Series A Due 2022 [Member] | Estimate of Fair Value Measurement [Member] |  |
Senior Notes, Fair Value | 24,301 | 24,737
US Senior Notes, Series B Due 2027 [Member] | Reported Value Measurement [Member] |  |
Senior Notes, Fair Value | 100,000 | 100,000
US Senior Notes, Series B Due 2027 [Member] | Estimate of Fair Value Measurement [Member] |  |
Senior Notes, Fair Value | 96,475 | 99,992
US Senior Notes, Series A Due 2025 [Member] | Reported Value Measurement [Member] |  |
Senior Notes, Fair Value | 50,000 |
US Senior Notes, Series A Due 2025 [Member] | Estimate of Fair Value Measurement [Member] |  |
Senior Notes, Fair Value | 48,081 |
US Senior Notes, Series B Due 2030 [Member] | Reported Value Measurement [Member] |  |
Senior Notes, Fair Value | 125,000 |
US Senior Notes, Series B Due 2030 [Member] | Estimate of Fair Value Measurement [Member] |  |
Senior Notes, Fair Value | $ 118,303 |

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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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