Amount of valuation reserve for inventory.

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Name:	us-gaap_InventoryValuationReserves
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Inventory - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Inventory - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Inventory [Line Items]
Inventory valuation reserves	$ 1.9		$ 54.0
Cost of goods sold
Inventory [Line Items]
Inventory valuation gains (losses)	(52.1)	$ (0.9)
LIFO inventory
Inventory [Line Items]
Inventory valuation reserves	$ 1.3	$ 39.4