Supplementary Oil And Gas Information (Unaudited) - Sources of Change in the Standardized Measure of Discounted Future Net Cash Flows (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves 1 [Roll Forward]
Sales of crude oil and natural gas produced, net of production costs	$ (18,544)	$ (17,672)	$ (18,174)
Net changes in sales prices and production costs	(19,233)	(11,189)	(47,145)
Extensions, discoveries and improved recovery	3,104	2,576	8,196
Changes in estimated future development costs	(890)	(2,101)	(1,511)
Purchases of proved reserves in place	5,971	15,463	0
Sales of proved reserves in place	0	(63)	(47)
Revisions of previous reserve estimates	5,322	(485)	6,647
Accretion of discount	14,369	14,059	17,769
Changes in production timing and other	671	2,507	(2,831)
Net change in income taxes	2,060	327	8,834
Net change	(7,170)	3,422	(28,262)
Balance – beginning of year	112,158	108,736	136,998
Balance – end of year	$ 104,988	$ 112,158	$ 108,736

Amount of decrease in standardized measure of discounted future net cash flow as a result of sales of minerals in place.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_DecreaseDueToSalesOfMineralsInPlace
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of extensions, discoveries and improved recovery of proved oil and gas reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_ExtensionsDiscoveriesAdditionsAndImprovedRecoveryLessRelatedCosts
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in estimated future development costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_IncreaseDecreaseInEstimatedFutureDevelopmentCosts
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in the estimated future income tax on future pretax net cash flows related to the entity's proved oil and gas reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_IncreaseDecreaseInFutureIncomeTaxExpenseEstimatesOnFutureCashFlowsRelatedToProvedOilAndGasReserves
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	srt_IncreaseDecreaseInStandardizedMeasureOfDiscountedFutureNetCashFlowRelatingToProvedOilAndGasReservesRollForward
Namespace Prefix:	srt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase in standardized measure of discounted future net cash flow as a result of purchases of minerals in place.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_IncreaseDueToPurchasesOfMineralsInPlace
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in sales and transfer prices and in production (lifting) costs related to future production.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_NetIncreaseDecreaseInSalesAndTransferPricesAndProductionCosts
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of revisions of estimated quantity of oil and gas in proved reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_RevisionsOfPreviousQuantityEstimates
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of (increase) decrease in standardized measure of discounted future net cash flow as a result of sales and transfers of oil and gas produced.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_SalesAndTransfersOfOilAndGasProducedNetOfProductionCosts
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of changes from other sources.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_StandardizedMeasureOfDiscountedFutureNetCashFlowOfProvedOilAndGasReservesOther
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in standardized measure of discounted future net cash flow relating to proved oil and gas reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_StandardizedMeasureOfDiscountedFutureNetCashFlowOfProvedOilAndGasReservesPeriodIncreaseDecrease
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of accretion of discount for the standardized measure of discounted future net cash flow related to proved oil and gas reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_StandardizedMeasureOfDiscountedFutureNetCashFlowRelatingToProvedOilAndGasReservesAccretionOfDiscount
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after discount, future accumulated cash outflow for development and production costs, and future income tax expense, of estimated future accumulated cash inflow for proved oil and gas reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Form 20-F
-Number Part II
-Section Item 18
-Subparagraph (Instruction 2)
-Publisher SEC

+ Details

Name:	srt_StandardizedMeasureOfDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant