Retirement Benefits - Components of Accumulated Other Comprehensive Loss to be Recognized over Next Fiscal Year (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventories valued under the LIFO method	$ 194.8	$ 231.4
Inventory write-offs	$ 38.6

Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration