COMMITMENTS - Summary of Other Commitments (Details) $ in Millions	Dec. 31, 2025 CAD ($)
Operating Credit Facilities
Other Commitments [Line Items]
Other commitment, Year 1	$ 0
Other commitment, Year 2	0
Other commitment, Year 3	0
Other commitment, Year 4	0
Other commitment, Year 5	3,300
Other commitment, Thereafter	0
Letters Of Credit
Other Commitments [Line Items]
Other commitment, Year 1	191
Other commitment, Year 2	0
Other commitment, Year 3	0
Other commitment, Year 4	0
Other commitment, Year 5	0
Other commitment, Thereafter	0
Guarantees
Other Commitments [Line Items]
Other commitment, Year 1	540
Other commitment, Year 2	0
Other commitment, Year 3	0
Other commitment, Year 4	0
Other commitment, Year 5	0
Other commitment, Thereafter	0
Guarantees \| Hydro One Inc.
Other Commitments [Line Items]
Other commitment, Year 1	475
Retirement Compensation Arrangements
Other Commitments [Line Items]
Other commitment, Year 1	166
Prudential Support From IESO
Other Commitments [Line Items]
Other commitment, Year 1	18
Various Operating Purposes
Other Commitments [Line Items]
Other commitment, Year 1	7
ONroute \| Hydro One Inc.
Other Commitments [Line Items]
Other commitment, Year 1	60
Aux Energy Inc. \| Hydro One Inc.
Other Commitments [Line Items]
Other commitment, Year 1	$ 5

Amount of commitment classified as other to be paid after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3

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