Note 5 - Inventories (Details Textual) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
LIFO Inventory Amount	$ 53.9		$ 53.9		$ 48.1
Percentage of LIFO Inventory	14.70%		14.70%		17.50%
Inventory, LIFO Reserve, Period Charge	$ 2.7	$ 0.7	$ 4.7	$ 1.5
Inventory Difference Using FIFO Basis	$ 0.7		$ 0.7		$ 5.3

The change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods, which change has been reflected in the statement of income during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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- Definition

The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 210
-SubTopic 10
-Section 50
-Paragraph 1
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- Definition

The percentage of LIFO (last in first out) inventory to total inventory as of the balance sheet date if other than 100 percent.

+ References

No definition available.

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- Definition

The difference in inventory balance if costed on a FIFO basis compared to LIFO basis.

+ References

No definition available.

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