| Note 2 - Significant Accounting Policies (Tables) | 12 Months Ended | |||||||||||||||||||||||||
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| Dec. 31, 2019 | ||||||||||||||||||||||||||
| Notes Tables | ||||||||||||||||||||||||||
| Property, Plant and Equipment, Useful Life [Table Text Block] | 
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| X | ||||||||||
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- Definition Tabular disclosure for the useful life of property, plant and equipment. No definition available. 
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| X | ||||||||||
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- References No definition available. 
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