Contingencies - Legal Proceedings (Details) $ in Millions, $ in Millions					9 Months Ended
	Jan. 05, 2024 USD ($)	Oct. 20, 2023 CAD ($)	Aug. 30, 2023 CAD ($)	Oct. 20, 2022 CAD ($)	Sep. 30, 2024 CAD ($) claim plaintiff appeal	Sep. 30, 2024 USD ($) claim plaintiff appeal
Other Commitments [Line Items]
Number of appeals from bankruptcy procedural grounds | appeal					2	2
Damaged rail cars and lost crude recovery
Other Commitments [Line Items]
Damages awarded	$ 3.9
Lac-Megantic Rail Accident | Claimed derailment damages
Other Commitments [Line Items]
Amount of fund to be distributed					$ 440
Lac-Megantic Rail Accident | Quebec Minister of Sustainable Development, Environment, Wildlife and Parks
Other Commitments [Line Items]
Value of damages sought					95
Lac-Megantic Rail Accident | Attorney General of Quebec
Other Commitments [Line Items]
Value of damages sought					315
Initial value of damages sought					409
Lac-Megantic Rail Accident | Initial Subrogated Insurers | Subrogated insurance claim
Other Commitments [Line Items]
Value of damages sought					15
Initial value of damages sought					$ 16
Number of subrogated insurer claims | claim					8	8
Lac-Megantic Rail Accident | Additional Subrogated Insurers | Subrogated insurance claim
Other Commitments [Line Items]
Value of damages sought					$ 3
Number of subrogated insurer claims | claim					2	2
Lac-Megantic Rail Accident | Class Action Plaintiffs
Other Commitments [Line Items]
Value of damages sought					$ 5
Number of plaintiffs | plaintiff					48	48
Lac-Megantic Rail Accident | MMAR Estate Representative | Damages for loss in business value
Other Commitments [Line Items]
Value of damages sought						$ 30.0
Lac-Megantic Rail Accident | WD Trustee | Damaged rail cars and lost crude recovery
Other Commitments [Line Items]
Value of damages sought						6.0
Lac-Megantic Rail Accident | WD Trustee | Reimbursement for settlement paid by consignor
Other Commitments [Line Items]
Value of damages sought						110.0
Lac-Megantic Rail Accident | WD Trustee | Reimbursement for settlement paid by consignee
Other Commitments [Line Items]
Value of damages sought						$ 60.0
AGQ Action and Promutuel Action | Class Action Plaintiffs
Other Commitments [Line Items]
Number of plaintiffs | plaintiff					3	3
Remington Development Corporation legal claim | Remington Development Corporation | Breach of contract
Other Commitments [Line Items]
Damages awarded			$ 165	$ 164
Total estimated damage		$ 225