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Note 10 - Developments in Accounting Pronouncements (Details Textual) $ in Millions | 9 Months Ended
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Sep. 30, 2017 USD ($)
Equity Securities [Member] |
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax | $ 3.2
Reclassification of Deferred Tax Assets from Current to Noncurrent [Member] | December 31, 2016 [Member] |
Prior Period Reclassification Adjustment | 12.3
Reclassification of Deferred Tax Liabilities from Current to Noncurrent [Member] | December 31, 2016 [Member] |
Prior Period Reclassification Adjustment | $ 1.3

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