Pensions and other postretirement benefits (Pension Plans with ABO and PBO in Excess of Plan Assets) (Details) - Pensions - CAD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Information for the pension plans with an accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	$ 434	$ 456
Fair value of plan assets	104	106
Information for the pension plans with a projected benefit obligation in excess of plan assets
Projected benefit obligation	434	456
Fair value of plan assets	$ 104	$ 106

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

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- Definition

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

+ References

+ Details

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-3

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- Definition

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

+ References

+ Details

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- Details

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