Summary of Assets Acquired and Liabilities Assumed (Parenthetical) (Detail) (CAD) In Millions, unless otherwise specified	1 Months Ended
Feb. 26, 2013
Business Acquisition [Line Items]
Risk adjusted discount rate	10.00%
Inflation rate	2.00%
Celtic
Business Acquisition [Line Items]
Property, plant and equipment	414
Total deferred income tax liabilities	414
Asset retirement obligations	(17)
Other	(20)
Total deferred income tax assets	(37)
Net deferred income tax liabilities	377

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Amount before allocation of valuation allowances of deferred tax liability to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from asset retirement obligations. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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