Supplemental Cash Flow Information (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Supplemental Cash Flow Elements [Abstract]
Payments of interest and commitment fees	$ 40.3	$ 33.4
Interest Paid, Capitalized	7.2	10.0
Incurred liabilities for fixed and intangible asset additions	52.9	$ 42.1
Other Asset Additions Incurred but Not yet Paid	$ 12.7