PENSION AND OTHER POSTRETIREMENT BENEFITS - EXPECTED BENEFIT PAYMENTS AND EMPLOYER CONTRIBUTIONS (Details) $ in Millions	Dec. 31, 2021 CAD ($)
Canada \| Pension
Benefits Expected to be Paid by the Company
2022	$ 197
2023	203
2024	208
2025	212
2026	217
2027-2031	1,163
Contributions expected to be paid in next fiscal year	110
Canada \| OPEB
Benefits Expected to be Paid by the Company
2022	12
2023	12
2024	12
2025	13
2026	13
2027-2031	67
Contributions expected to be paid in next fiscal year	12
United States \| Pension
Benefits Expected to be Paid by the Company
2022	80
2023	78
2024	78
2025	76
2026	77
2027-2031	374
Contributions expected to be paid in next fiscal year	4
United States \| OPEB
Benefits Expected to be Paid by the Company
2022	17
2023	15
2024	14
2025	13
2026	12
2027-2031	51
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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-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 55
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921

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