Supplemental Cash Flow Information (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Payments of interest and commitment fees	$ 80.0	$ 78.4
Interest Paid, Capitalized	11.9	12.3
Incurred liabilities for fixed and intangible asset additions	$ 23.2	$ 55.6