The amount of current derivative financial assets. [Refer: Derivative financial assets]

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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: Financial instruments, class [member]; Financial liabilities]

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The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) 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 deliver 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, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are 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. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

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The percentage of voting equity interests acquired in a business combination. [Refer: Business combinations [member]]

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The amount of risk exposure associated with financial instruments with a shared characteristic that identifies a concentration of risks. [Refer: Financial instruments, class [member]]

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Capacity Of Generation Units, Power

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Derivative, Forward Price

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Increase (Decrease) in Derivative Forward Power Prices, Reasonably Possible

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Long-term Fixed Price Power Sale Contract, Delivery Volume

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Sensitivity Analysis In Derivative, Basis Relationship, Percent

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Financial Instruments (Details) $ in Millions	12 Months Ended
Financial Instruments (Details) $ in Millions	Dec. 31, 2021 USD ($)	Dec. 31, 2020 CAD ($)	Dec. 31, 2021 CAD ($) MW	Dec. 31, 2020 USD ($)	Dec. 31, 2019 CAD ($)
Disclosure of detailed information about financial instruments [line items]
Risk management assets		$ 171	$ 308
Financial liabilities		$ 3,361	$ 3,267
White Rock East And White Rock West Wind Power Projects
Disclosure of detailed information about financial instruments [line items]
Capacity of facility (in megawatts) \| MW			300
Long-term wind energy sale – Canada
Disclosure of detailed information about financial instruments [line items]
Percentage of voting equity interests acquired			49.00%
Long-term wind energy sale – Canada \| Pembina
Disclosure of detailed information about financial instruments [line items]
Percentage of voting equity interests acquired			37.70%
Long-term wind energy sale - Central US
Disclosure of detailed information about financial instruments [line items]
Percentage of voting equity interests acquired			100.00%
Fixed-price contracts \| Minimum
Disclosure of detailed information about financial instruments [line items]
Long-term fixed price power sale contract, delivery volume \| MW			300
Fixed-price contracts \| Maximum
Disclosure of detailed information about financial instruments [line items]
Long-term fixed price power sale contract, delivery volume \| MW			380
Coal transportation – US \| Minimum
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis in derivative, basis relationship, percent		80.00%
Sensitivity analysis in derivative, non-standard shape factors, percent		0.00%
Coal transportation – US \| Maximum
Disclosure of detailed information about financial instruments [line items]
Sensitivity analysis in derivative, basis relationship, percent		120.00%
Sensitivity analysis in derivative, non-standard shape factors, percent		4.00%
Level III \| Long-term contracts \| Fixed-price contracts
Disclosure of detailed information about financial instruments [line items]
Forward power price ranges per MWh				$ 1
Level III \| Long-term contracts \| Fixed-price contracts \| Minimum
Disclosure of detailed information about financial instruments [line items]
Increase (decrease) in derivative forward power prices, reasonable possible	$ 3
Level III \| Long-term contracts \| Fixed-price contracts \| Maximum
Disclosure of detailed information about financial instruments [line items]
Increase (decrease) in derivative forward power prices, reasonable possible	(2)
Level III \| Long-term contracts \| Forward contract
Disclosure of detailed information about financial instruments [line items]
Forward power price ranges per MWh				$ 6
Increase (decrease) in derivative forward power prices, reasonable possible	$ (6)
Recurring fair value measurement \| Level I
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic		$ (13)	$ 12
Recurring fair value measurement \| Level III
Disclosure of detailed information about financial instruments [line items]
Risk exposure associated with instruments sharing characteristic		582	159		$ 686
Recurring fair value measurement \| Level III \| Financial liabilities at fair value through profit or loss, category [member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities		33	146
Recurring fair value measurement \| Level III \| Financial assets at fair value through profit or loss, category [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets		$ 615	$ 305