Basis of Presentation and Summary of Significant Accounting Policies - Capital Additions and Related Depreciation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Interest Costs Capitalized	$ 14.2	$ 17.6	$ 16.6
Other Direct And Indirect Costs Capitalized	$ 29.2	$ 33.2	$ 33.7
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Middle [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	30 years