Financial Instruments (Details) (CAD) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Risk Management [Abstract]
Unamortized gain included in accumulated other comprehensive loss	8	10
Unamortized gain included in accumulated other comprehensive loss, after-tax	6	7
Financial liabilities [Abstract]
Revolving credit facility, borrowing capacity	800
Carrying amount [Member]
Financial assets [Abstract]
Investments (Note 6)	31	25
Financial liabilities [Abstract]
Total debt (Note 9)	6,576	6,071
Fair value [Member]
Financial assets [Abstract]
Investments (Note 6)	126	114
Financial liabilities [Abstract]
Total debt (Note 9)	7,978	6,937

Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investments accounted for under the cost method of accounting as of the balance sheet date.

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