Derivative Instruments and Hedging Activities Fair Value Balance Sheet (Details) CAD in Millions, $ in Millions	Sep. 30, 2016 USD ($)	Jul. 07, 2016 CAD	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Foreign currency forwards [Member]
Derivatives designated as hedging instruments:
Derivative, notional amount | CAD		CAD 965.5
Swaption [Member]
Derivatives designated as hedging instruments:
Derivative, notional amount			$ 855.0
Designated as Hedging Instrument [Member]
Derivatives designated as hedging instruments:
Derivative asset, fair value, designated as hedging instrument	$ 13.0			$ 44.1
Derivative liability, fair value, designated as hedging instrument	(3.8)			0.0
Designated as Hedging Instrument [Member] | Foreign currency forwards [Member]
Derivatives designated as hedging instruments:
Derivative, notional amount	344.8			300.3
Designated as Hedging Instrument [Member] | Foreign currency forwards [Member] | Other current assets [Member]
Derivatives designated as hedging instruments:
Derivative asset, fair value, designated as hedging instrument	11.1			28.4
Designated as Hedging Instrument [Member] | Foreign currency forwards [Member] | Other non-current assets [Member]
Derivatives designated as hedging instruments:
Derivative asset, fair value, designated as hedging instrument	1.9			15.7
Designated as Hedging Instrument [Member] | Foreign currency forwards [Member] | Accounts payable and other current liabilities [Member]
Derivatives designated as hedging instruments:
Derivative liability, fair value, designated as hedging instrument	(2.2)			0.0
Designated as Hedging Instrument [Member] | Foreign currency forwards [Member] | Other liabilities [Member]
Derivatives designated as hedging instruments:
Derivative liability, fair value, designated as hedging instrument	(1.6)			0.0
Not Designated as Hedging Instrument [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	5.3			0.6
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(8.6)			(22.0)
Not Designated as Hedging Instrument [Member] | Foreign currency forwards [Member]
Derivatives designated as hedging instruments:
Derivative, notional amount	100.0
Not Designated as Hedging Instrument [Member] | Foreign currency forwards [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	0.0
Not Designated as Hedging Instrument [Member] | Foreign currency forwards [Member] | Accounts payable and other current liabilities [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(0.1)
Not Designated as Hedging Instrument [Member] | Commodity swaps [Member]
Derivatives designated as hedging instruments:
Derivative, notional amount	128.2			120.3
Not Designated as Hedging Instrument [Member] | Commodity swaps [Member] | Other current assets [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	1.6			0.4
Not Designated as Hedging Instrument [Member] | Commodity swaps [Member] | Other non-current assets [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	3.7			0.2
Not Designated as Hedging Instrument [Member] | Commodity swaps [Member] | Accounts payable and other current liabilities [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	(5.2)			(12.5)
Not Designated as Hedging Instrument [Member] | Commodity swaps [Member] | Other liabilities [Member]
Derivatives not designated as hedging instruments:
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	$ (3.3)			$ (9.5)