PENSION AND OTHER POSTRETIREMENT BENEFITS - Expected Benefit Payments and Employer Contributions (Details) $ in Millions	Dec. 31, 2022 CAD ($)
Canada \| Pension
Benefits Expected to be Paid by the Company
2023	$ 204
2024	210
2025	216
2026	221
2027	226
2028-2032	1,208
Contributions expected to be paid in next fiscal year	29
Canada \| OPEB
Benefits Expected to be Paid by the Company
2023	12
2024	12
2025	13
2026	13
2027	13
2028-2032	68
Contributions expected to be paid in next fiscal year	12
United States \| Pension
Benefits Expected to be Paid by the Company
2023	88
2024	87
2025	87
2026	88
2027	90
2028-2032	424
Contributions expected to be paid in next fiscal year	5
United States \| OPEB
Benefits Expected to be Paid by the Company
2023	16
2024	15
2025	14
2026	13
2027	12
2028-2032	49
Contributions expected to be paid in next fiscal year	$ 6

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Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
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-Publisher FASB
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921

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