Asset Impairments - Components of Asset Impairment Charge (Detail) CAD in Millions	12 Months Ended
Dec. 31, 2013 CAD
Impaired Long-Lived Assets Held and Used [Line Items]
Total asset impairment charge	CAD 435
Dakota, Minnesota & Eastern Railroad - West [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Property, plant and equipment	426
Intangible assets	2
Goodwill	6
Total asset impairment charge	434
Accruals for future costs	CAD 1

Impairment of Long Lived Assets, Intangibles and Goodwill

No definition available.

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- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of an intangible asset (excluding goodwill) to fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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