Properties - Capital Leases Included in Properties (Details) - CAD CAD in Millions	Dec. 31, 2015	Dec. 31, 2014
Capital Leased Assets [Line Items]
Cost	CAD 312	CAD 312
Accumulated depreciation	97	88
Net book value	215	224
Buildings [Member]
Capital Leased Assets [Line Items]
Cost	1	1
Accumulated depreciation	1	1
Net book value	0	0
Rolling stock [Member]
Capital Leased Assets [Line Items]
Cost	311	311
Accumulated depreciation	96	87
Net book value	CAD 215	CAD 224

Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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.

+ Details

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- Definition

The total gross amount less the charge for the use of the long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6455398&loc=d3e45280-112737

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45014-112735

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 2)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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