Property, Plant And Equipment (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Property, Plant And Equipment [Abstract]
Total accumulated depreciation	$ 522.0		$ 502.9
Unpaid capital expenditure liabilities	$ 4.8	$ 2.5