Financial and capital management - Change in Allowance for Doubtful Accounts (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Trade receivables
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Financial assets at beginning of period	$ 3,841
Financial assets at end of period	4,185	$ 3,841
Trade receivables \| Allowance for doubtful accounts
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Financial assets at beginning of period	(118)	(129)
Additions	(169)	(126)
Usage and reversals	167	137
Financial assets at end of period	(120)	(118)
Contract assets \| Allowance for doubtful accounts
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Financial assets at beginning of period	(18)	(19)
Additions	(20)	(40)
Usage and reversals	20	41
Financial assets at end of period	(18)	(18)
Current contract assets \| Allowance for doubtful accounts
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Financial assets at beginning of period	(6)
Financial assets at end of period	(6)	(6)
Noncurrent contract assets \| Allowance for doubtful accounts
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]
Financial assets at beginning of period	(12)
Financial assets at end of period	$ (12)	$ (12)

- Definition

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Classes of financial instruments [domain]; Financial liabilities]

+ References + Details