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Employee Benefit Plans (Accumulated Benefit Obligation (ABO)) (Details) - Pension Plan [Member] - CAD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
ABO	$ 1,608	$ 2,462
Fair Value of Plan Assets	1,409	2,171
Funded Status	$ (199)	$ (291)

X

- Definition

If aggregate disclosures are presented, the aggregate funded status of plan assets for plans with benefit obligations in excess of plan assets which are measured as the difference between the fair value of plan assets and the benefit obligation.

+ References

No definition available.

+ Details

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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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X

- Definition

Amount of benefit obligation for defined benefit plan with benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920

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- Definition

Fair value of plan assets for defined benefit plan with benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920

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