Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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ACQUISITIONS AND DISPOSITIONS - Noncontrolling Interest Investment and Disposition (Narrative) (Details) - CAD ($) $ in Millions			9 Months Ended
	Sep. 03, 2026	Jul. 02, 2025	Sep. 30, 2026	Sep. 30, 2025
Class A Units
Disposal Group, Including Discontinued Operations [Line Items]
Proceeds from investment by redeemable noncontrolling interest in subsidiary			$ 0	$ 736
Class II Units
Disposal Group, Including Discontinued Operations [Line Items]
Proceeds from investment by redeemable noncontrolling interest in subsidiary			$ 729	$ 0
Westcoast Expansion Financing Limited Partnership \| Class II Units \| KKR
Disposal Group, Including Discontinued Operations [Line Items]
Investment by noncontrolling interest	$ 729
Proceeds from investment by redeemable noncontrolling interest in subsidiary	729
Cash contribution in future	$ 2,000
Westcoast LP \| Class A Units \| First Nations Partnership
Disposal Group, Including Discontinued Operations [Line Items]
Investment by noncontrolling interest		$ 736
Proceeds from investment by redeemable noncontrolling interest in subsidiary		$ 736
Ownership interest percentage held by noncontrolling owners		12.50%