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Derivatives Instruments (Notional Volumes of Outstanding Derivatives Designated for Regulatory Deferral) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 CAD ($) MMBTU MWh t
Commodity swaps and forwards | Coal | 2024
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh | t	1
Commodity swaps and forwards | Coal | 2025-2026
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh | t	0
Commodity swaps and forwards | Natural gas | 2024
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh	16
Commodity swaps and forwards | Natural gas | 2025-2026
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh	10
Commodity swaps and forwards | Power | 2024
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh | MWh	1
Commodity swaps and forwards | Power | 2025-2026
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh | MWh	1
Physical natural gas purchases | Natural gas | 2024
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh	7
Physical natural gas purchases | Natural gas | 2025-2026
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) | MWh	6
Foreign Exchange Swaps and Forward Contracts | 2024
Derivative [Line Items]
Notional volumes of outstanding derivatives designated as cash flow hedges that are expected to settle | $	$ 241
Weighted average rate	1.3155
% of USD requirements	63.00%
Foreign Exchange Swaps and Forward Contracts | 2025-2026
Derivative [Line Items]
Notional volumes of outstanding derivatives designated as cash flow hedges that are expected to settle | $	$ 70
Weighted average rate	1.3197
% of USD requirements	17.00%

X

- Definition

Average contractual rate at which a foreign currency can be purchased or sold.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-5

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- Definition

Nominal energy measure used to calculate payments on a derivative instrument.

+ References

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- Definition

The percentage of expected requirements covered by the aggregate notional amount of derivative contracts expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract as a percentage of expected need.

+ References

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

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