Pensions and Other Postretirement Benefits (Expected Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2023 CAD ($)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024	$ 1,051
2025	1,049
2026	1,039
2027	1,030
2028	1,018
Years 2029 to 2033	4,900
Other postretirement benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024	12
2025	11
2026	11
2027	10
2028	10
Years 2029 to 2033	$ 44

Amount of benefit for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following current fiscal year.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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Amount of benefit for defined benefit plan expected to be paid in next fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in fifth fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in fourth fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in third fiscal year following current fiscal year.

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Amount of benefit for defined benefit plan expected to be paid in second fiscal year following current fiscal year.

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