Derivatives Instruments (Notional Volumes of Outstanding Derivatives Designated for Regulatory Deferral) (Details) $ in Millions	12 Months Ended
Dec. 31, 2024 CAD ($) MMBTU MWh T
Commodity swaps and forwards \| Coal \| 2025
Derivative [Line Items]
Coal (metric tonnes) \| T	1
Commodity swaps and forwards \| Coal \| 2026-2027
Derivative [Line Items]
Coal (metric tonnes) \| T	0
Commodity swaps and forwards \| Natural gas \| 2025
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) \| MWh	21
Commodity swaps and forwards \| Natural gas \| 2026-2027
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) \| MWh	23
Commodity swaps and forwards \| Power \| 2025
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) \| MWh \| MWh	1
Commodity swaps and forwards \| Power \| 2026-2027
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) \| MWh \| MWh	0
Physical natural gas purchases \| Natural gas \| 2025
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) \| MWh	6
Physical natural gas purchases \| Natural gas \| 2026-2027
Derivative [Line Items]
Natural Gas (Mmbtu) / Power (MWh) \| MWh	0
Foreign Exchange Swaps and Forward Contracts \| 2025
Derivative [Line Items]
Notional volumes of outstanding derivatives designated as cash flow hedges that are expected to settle \| $	$ 208
Weighted average rate	1.3361
% of USD requirements	50.00%
Foreign Exchange Swaps and Forward Contracts \| 2026-2027
Derivative [Line Items]
Notional volumes of outstanding derivatives designated as cash flow hedges that are expected to settle \| $	$ 69
Weighted average rate	1.3296
% of USD requirements	17.00%

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

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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

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Nominal mass used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

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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

No definition available.

+ Details

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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

+ Details

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