Leases - Supplemental Information Related to Leases (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating cash outflows from operating leases	$ 96	$ 64	$ 64
Operating cash outflows from finance leases	2	6	10
Financing cash outflows from finance leases	13	104	8
ROU assets obtained in exchange for lease liabilities
Operating leases	62	34	36
Finance leases	$ 0	$ 0	$ 5

Right-of-use assets obtained in exchange for lease liabilities

No definition available.

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- Definition

Amount of interest paid on finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
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-URI https://asc.fasb.org//1943274/2147478964/842-20-50-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Section 45
-Paragraph 5
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479041/842-20-45-5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cash outflow for principal payment on finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
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-URI https://asc.fasb.org//1943274/2147478964/842-20-50-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147479041/842-20-45-5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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- Definition

Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479041/842-20-45-5

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-URI https://asc.fasb.org//1943274/2147478964/842-20-50-4

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase in right-of-use asset obtained in exchange for finance lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
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-Paragraph 53
-Publisher FASB
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-URI https://asc.fasb.org//1943274/2147478964/842-20-50-4

+ Details

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Balance Type:	debit
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- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

+ References

+ Details

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