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Defined Benefit Obligation and Other Long-Term Liabilities - Narrative (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Disclosure of fair value measurement of liabilities [line items]
Increase (decrease) in defined benefit obligation	$ (78)
Defined benefit obligation	150	$ 228
Voluntary contribution	$ 35
Increase in discount rates	1.00%
Pro Forma
Disclosure of fair value measurement of liabilities [line items]
Increase (decrease) in defined benefit obligation	$ 39
Level II | Recurring fair value measurement
Disclosure of fair value measurement of liabilities [line items]
Commodity risk management assets and liabilities	173	$ 122
Level II | Recurring fair value measurement | retail power contract liabilities
Disclosure of fair value measurement of liabilities [line items]
Commodity risk management assets and liabilities	129
Risk management assets | Level II | Recurring fair value measurement
Disclosure of fair value measurement of liabilities [line items]
Commodity risk management assets and liabilities	$ 139

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

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- Definition

The increase (decrease) in the net defined benefit liability (asset). [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Number 19
-IssueDate 2022-03-24
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- Definition

The amount of non-current net defined benefit liability. [Refer: Net defined benefit liability]

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-IssueDate 2022-03-24
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- Definition

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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-IssueDate 2022-03-24
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Increase in Discount Rates

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Voluntary Contribution

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