Debt Debt Issuance Costs (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014
Debt Instrument [Line Items]
Debt Issuance Costs, Amortization Period	7 years
Debt Inssuance Costs [Roll Forward]
Balance at December 31, 2013	$ 19.9	$ 13.9
Amortization of debt issuance costs		2.9
Balance at September 30, 2014	19.9	19.9
$1.9 billion debt financing arrangement [Member]
Debt Inssuance Costs [Roll Forward]
Capitalized debt issuance costs from April 28, 2014 $1.9 billion debt financing arrangement		14.3
$1.5 billion debt financing arrangement [Member]
Debt Inssuance Costs [Roll Forward]
Capitalized debt issuance costs from April 28, 2014 $1.9 billion debt financing arrangement		2.1
Loss on debt extinguishment from July 26, 2011 $1.5 billion debt financing arrangement fees that were previously capitalized		2.1
Other Noncurrent Assets [Member] | $1.9 billion debt financing arrangement [Member]
Debt Inssuance Costs [Roll Forward]
Capitalized debt issuance costs from April 28, 2014 $1.9 billion debt financing arrangement		11.0
Discharge of Debt [Member] | $1.9 billion debt financing arrangement [Member]
Debt Inssuance Costs [Roll Forward]
Capitalized debt issuance costs from April 28, 2014 $1.9 billion debt financing arrangement		$ 3.3
Minimum [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Amortization Period	5 years
Maximum [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Amortization Period	8 years