Derivative Instruments and Hedging Activities Fair Value Balance Sheet (Details) In Millions, unless otherwise specified	Mar. 31, 2014 Designated as Hedging Instrument [Member] USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Cross currency swaps CAD	Dec. 31, 2013 Designated as Hedging Instrument [Member] Cross currency swaps Other assets USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Cross currency swaps Long term derivative liability USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Foreign currency forwards USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Foreign currency forwards USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Foreign currency forwards Other current assets USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Foreign currency forwards Other current assets USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Foreign currency forwards Other assets USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Foreign currency forwards Other assets USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Foreign currency forwards Current derivative liability USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Foreign currency forwards Current derivative liability USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Foreign currency forwards Long term derivative liability USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Foreign currency forwards Long term derivative liability USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Commodity swaps [Member] kWh	Dec. 31, 2013 Designated as Hedging Instrument [Member] Commodity swaps [Member] kWh	Mar. 31, 2014 Designated as Hedging Instrument [Member] Commodity swaps [Member] Other current assets USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Commodity swaps [Member] Other current assets USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Commodity swaps [Member] Other assets USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Commodity swaps [Member] Other assets USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Commodity swaps [Member] Current derivative liability USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Commodity swaps [Member] Current derivative liability USD ($)	Mar. 31, 2014 Designated as Hedging Instrument [Member] Commodity swaps [Member] Long term derivative liability USD ($)	Dec. 31, 2013 Designated as Hedging Instrument [Member] Commodity swaps [Member] Long term derivative liability USD ($)	Mar. 31, 2014 Not Designated as Hedging Instrument [Member] USD ($)	Dec. 31, 2013 Not Designated as Hedging Instrument [Member] USD ($)	Dec. 31, 2013 Not Designated as Hedging Instrument [Member] Commodity swaps [Member] t	Mar. 31, 2014 Not Designated as Hedging Instrument [Member] Commodity swaps [Member] t	Mar. 31, 2014 Not Designated as Hedging Instrument [Member] Commodity [Member] Other current assets USD ($)	Dec. 31, 2013 Not Designated as Hedging Instrument [Member] Commodity [Member] Other current assets USD ($)	Mar. 31, 2014 Not Designated as Hedging Instrument [Member] Commodity [Member] Other assets USD ($)	Dec. 31, 2013 Not Designated as Hedging Instrument [Member] Commodity [Member] Other assets USD ($)	Mar. 31, 2014 Not Designated as Hedging Instrument [Member] Commodity [Member] Current derivative liability USD ($)	Dec. 31, 2013 Not Designated as Hedging Instrument [Member] Commodity [Member] Current derivative liability USD ($)	Mar. 31, 2014 Not Designated as Hedging Instrument [Member] Commodity [Member] Long term derivative liability USD ($)	Dec. 31, 2013 Not Designated as Hedging Instrument [Member] Commodity [Member] Long term derivative liability USD ($)
Derivatives designated as hedging instruments:
Commodity swaps, Notional Amount																846,200,000	848,800,000
Derivative asset, fair value, designated as hedging instrument	$ 30.7	$ 20.0		$ 0				$ 17.0	$ 11.5	$ 12.9	$ 8.2							$ 0.7	$ 0.2	$ 0.1	$ 0.1
Derivative fair value, liability	(1.0)	(72.2)			71.7							0	0	0	0							(0.8)	(0.2)	(0.2)	(0.3)
Derivative, Notional Amount			240.7			422.6	476.1
Derivatives not designated as hedging instruments:
Commodity swaps, Notional Amount																												55,653	57,222
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value																										0.3	0			0.2	0	0.1	0
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value																										$ (5.9)	$ (4.7)							$ (2.2)	$ (2.0)	$ (3.7)	$ (2.7)