Fair Value of Pension Plan Assets Including Level Within Fair Value Hierarchy (Detail) (CAD) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	5,872		5,114
Canadian Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	932		811
Non-Canadian Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1,911		1,657
Corporate Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	654		473
Government Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	2,161		1,982
Asset Backed Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value			5
Mortgage Funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1		1
Equities - Venture Capital
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	188		158
Cash
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	25		27
Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	12		9
Quoted Prices In Active Markets For Identical Assets (Level 1) | Cash
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	12		9
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	5,671		4,946
Significant Other Observable Inputs (Level 2) | Canadian Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	932	[1]	811	[1]
Significant Other Observable Inputs (Level 2) | Non-Canadian Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1,911	[1]	1,657	[1]
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	654	[2]	473	[2]
Significant Other Observable Inputs (Level 2) | Government Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	2,161	[2]	1,982	[2]
Significant Other Observable Inputs (Level 2) | Asset Backed Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value			5	[2]
Significant Other Observable Inputs (Level 2) | Cash
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	13	[3]	18	[3]
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	189		159
Significant Unobservable Inputs (Level 3) | Mortgage Funds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	1	[4]	1	[4]
Significant Unobservable Inputs (Level 3) | Equities - Venture Capital
Defined Benefit Plan Disclosure [Line Items]
Total plan assets at fair value	188	[5]	158	[5]

[1] For company equity securities held in the form of fund units that are redeemable at the measurement date, the unit value is treated as a Level 2 input. The fair value of the securities owned by the funds is based on observable quoted prices on active exchanges, which are Level 1 inputs.

[2] For corporate, government and asset-backed debt securities, fair value is based on observable inputs of comparable market transactions.

[3] For cash balances that are held in Level 2 funds prior to investment in those fund units, the cash value is treated as a Level 2 input.

[4] For mortgage funds, fair value represents the principal outstanding which is guaranteed by Canada Mortgage and Housing Corporation.

[5] For venture capital partnership investments, fair value is generally established by using revenue or earnings multiples or other relevant market data including Initial Public Offerings.