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Contingencies (Details) $ in Millions, $ in Millions, $ in Millions							6 Months Ended
	Jan. 05, 2024 USD ($)	Oct. 20, 2023 CAD ($)	Aug. 30, 2023 CAD ($)	Jan. 13, 2023 plaintiff	Oct. 20, 2022 CAD ($)	Jan. 24, 2022 procedural_ground	Jun. 30, 2026 CAD ($) claim plaintiff	Jun. 30, 2026 USD ($) plaintiff	Jun. 30, 2026 MXN ($) plaintiff	Dec. 31, 2025 CAD ($)
Commitments and Contingencies [Line Items]
Accrual for Environmental Loss Contingencies							$ 248			$ 241
Term for expected payments to be made							10 years	10 years	10 years
Foreign Tax Authority \| Mexican Tax Authority \| Tax Year 2014
Commitments and Contingencies [Line Items]
Tax assessment amount							$ 540		$ 6,667
WD Trustee
Commitments and Contingencies [Line Items]
Damages awarded	$ 3.9
Lac-Megantic Rail Accident
Commitments and Contingencies [Line Items]
Number of plaintiffs \| plaintiff				3
Lac-Megantic Rail Accident \| Claimed derailment damages
Commitments and Contingencies [Line Items]
Amount of fund to be distributed							440
Lac-Megantic Rail Accident \| Quebec Minister of Sustainable Development, Environment, Wildlife and Parks
Commitments and Contingencies [Line Items]
Value of damages sought							95
Lac-Megantic Rail Accident \| Attorney General of Quebec
Commitments and Contingencies [Line Items]
Value of damages sought							231
Initial value of damages sought							409
Lac-Megantic Rail Accident \| Initial Subrogated Insurers \| Subrogated insurance claim
Commitments and Contingencies [Line Items]
Value of damages sought							14
Initial value of damages sought							$ 16
Number of subrogated insurer claims \| claim							8
Lac-Megantic Rail Accident \| Additional Subrogated Insurers \| Subrogated insurance claim
Commitments and Contingencies [Line Items]
Value of damages sought							$ 3
Number of subrogated insurer claims \| claim							2
Lac-Megantic Rail Accident \| Class Action Plaintiffs
Commitments and Contingencies [Line Items]
Value of damages sought							$ 5
Number of plaintiffs \| plaintiff							48	48	48
Number of plaintiffs who opted out \| plaintiff							2	2	2
Number of appeals from bankruptcy procedural grounds \| procedural_ground						2
Lac-Megantic Rail Accident \| MMAR Estate Representative \| Damages for loss in business value
Commitments and Contingencies [Line Items]
Value of damages sought								$ 30.0
Lac-Megantic Rail Accident \| WD Trustee \| Damaged rail cars and lost crude recovery
Commitments and Contingencies [Line Items]
Value of damages sought								6.0
Lac-Megantic Rail Accident \| WD Trustee \| Reimbursement for settlement paid by consignor
Commitments and Contingencies [Line Items]
Value of damages sought								110.0
Lac-Megantic Rail Accident \| WD Trustee \| Reimbursement for settlement paid by consignee
Commitments and Contingencies [Line Items]
Value of damages sought								$ 60.0
Remington Development Corporation legal claim \| Remington Development Corporation \| Breach of contract
Commitments and Contingencies [Line Items]
Damages awarded			$ 165		$ 164
Total estimated damage		$ 232