Derivatives (Narrative) (Details) (CAD) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2014
Forward contract
Derivative [Line Items]
Foreign currency contract settlement, amount (in Canadian dollars)	86	86
Diesel swap \| Fixed price swap contracts
Derivative [Line Items]
Fixed price swap contract (in gallons)		5,300,000

Nominal volume used to calculate payments on a derivative instrument.

No definition available.

Name:	us-gaap_DerivativeNonmonetaryNotionalAmountVolume
Namespace Prefix:	us-gaap_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	duration