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Employee Benefit Plans (Amounts to be Amortized in the Next Fiscal Year) (Details) $ in Millions	Dec. 31, 2018 CAD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Future Amortization of Gain (Loss)	$ 36
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	1
Regulated assets	(21)
Total	(56)
Non-pension Benefit Plans [Member
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Future Amortization of Gain (Loss)	2
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	6
Regulated assets	(2)
Total	$ 2

X

- Definition

Amount included in accumulated other comprehensive income (AOCI) related to Regulated assets expected to be recognized as components of net periodic benefit cost (credit) for the fiscal year that follows the most recent annual statement of financial position.

+ References

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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

Amount of cost (credit) included in accumulated other comprehensive (income) loss expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (s)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (s)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount included in accumulated other comprehensive (income) loss for prior service cost (credit) expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (s)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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