Fair Value Measurements (Fair value of the Level 3 financial assets) (Details) $ in Millions	12 Months Ended
Dec. 31, 2022 CAD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 104
Realized gains included in fuel for generation and purchased power	64
Unrealized gains included in regulatory liabilities	28
Total realized and unrealized gains (losses) included in non-regulated operating revenues	22
Ending Balance	90
Regulatory deferral \| Physical natural gas purchases \| Energy Related derivative
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	88
Realized gains included in fuel for generation and purchased power	64
Unrealized gains included in regulatory liabilities	28
Total realized and unrealized gains (losses) included in non-regulated operating revenues	0
Ending Balance	52
Not Designated as Hedging Instrument \| Energy Related derivative \| Non-regulated operating revenues
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	104
Realized gains included in fuel for generation and purchased power	64
HFT derivatives \| Energy Related derivative \| Non-regulated operating revenues
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	104
Realized gains included in fuel for generation and purchased power	(64)
Unrealized gains included in regulatory liabilities	28
Total realized and unrealized gains (losses) included in non-regulated operating revenues	22
Ending Balance	90
HFT derivatives \| Power \| Energy Related derivative
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	4
Realized gains included in fuel for generation and purchased power	0
Unrealized gains included in regulatory liabilities	0
Total realized and unrealized gains (losses) included in non-regulated operating revenues	0
Ending Balance	4
HFT derivatives \| Natural gas \| Energy Related derivative
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	12
Realized gains included in fuel for generation and purchased power	0
Unrealized gains included in regulatory liabilities	0
Total realized and unrealized gains (losses) included in non-regulated operating revenues	22
Ending Balance	$ 34

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- Definition

Amount of increase (decrease) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19279-110258

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- Definition

Amount of gain (loss) recognized in other comprehensive income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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