Derivative Instruments Derivatives Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) from Components Excluded from Assessment of Cash Flow Hedge Effectiveness, Net	$ 0.0	$ 0.0
Accumulated Other Comprehensive Loss, Cumulative Changes in Net Loss from Cash Flow Hedges, Effect Net of Tax	15.0		$ 16.2
Other Comprehensive Loss, Reclassification Adjustment from AOCI on Derivatives, Net of Tax	5.1	4.7
Cash Flow Hedge Loss to be Reclassified within Twelve Months	31.2
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	0.0	0.0
OTC commodity swaps | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Total	(2.9)	(7.8)
Not Designated as Hedging Instrument [Member] | OTC commodity swaps | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Gains on derivatives not designated as hedging instruments	2.7	0.5
Designated as Hedging Instrument [Member] | OTC commodity swaps | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Realized losses reclassified out of OCI on derivatives designated as cash flow hedging instruments	(7.8)	(7.3)
Gains (losses) recognized due to cash flow hedging instruments ineffectiveness	$ 2.2	$ (1.0)