The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount classified as property, plant and equipment attributable to disposal group held for sale or disposed of.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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Note 6 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Depreciation, Total		$ 46.0	$ 39.5
Other Assets [Member]
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		$ 4.6		$ 4.6
Headquarters Building and Adjoining Property [Member]
Proceeds from Sale of Property Held-for-sale	$ 10.1
Gain (Loss) on Disposition of Property Plant Equipment, Total	$ 6.6