Inventories - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Reserve for inventory valuation	$ 20.8	$ 18.0
Percentage of reserve for inventory valuation	12.00%	10.70%

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