Inventories Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory valuation reserves	$ 70,800,000	$ 38,800,000
LIFO inventory amount	300,900,000	$ 0
Replacement costs over stated LIFO value	600,000
Effect of LIFO inventory liquidation on income	$ 0