| Note 10 - Derivative Financial Instruments - Average USD Fair Value Measurements for Contracts Rates (Details) | Jul. 01, 2018 | Dec. 31, 2017 | 
|---|---|---|
| Average USD:CAD contract rate | 18.52% | 18.69% | 
| Average USD:CAD mark-to-market rate | 20.00% | 20.11% | 
| Canada, Dollars | ||
| Average USD:CAD contract rate | 1.24% | 1.29% | 
| Average USD:CAD mark-to-market rate | 1.31% | 1.26% | 
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- Definition Market to market average stated rate on a group of interest rate forward or futures contracts. No definition available. 
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| X | ||||||||||
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- Definition Average stated rate on a group of interest rate forward or futures contracts. No definition available. 
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| X | ||||||||||
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- Details 
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