Financial Instruments - Reconciliation of Changes in the Fair Value of Cenovus's Risk Management Assets and Liabilities (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2024 CAD ($)
Disclosure of detailed information about financial instruments [abstract]
As at December 31, 2023	$ 12
Change in Fair Value of Contracts in Place, Beginning of Year	(11)
Change in Fair Value of Contracts Entered Into During the Period	(23)
Fair Value of Contracts Realized During the Period	11
As at September 30, 2024	$ (11)