Accounts Receivable Sale Program (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jul. 20, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounts Receivable Sale Program [Line Items]
Maximum Limit Accounts Receivable Sale Program				$ 40.0
Trade Accounts Receivable Sold		$ 40.0	$ 40.0	80.0	$ 65.0
Amount Received From Trade Accounts Receivable Sold To Third Party		$ 39.9	$ 39.9	$ 79.8	$ 64.9
Subsequent Event [Member]
Accounts Receivable Sale Program [Line Items]
Maximum Limit Accounts Receivable Sale Program	$ 80.0