Property, Plant And Equipment - Schedule of Jointly-Owned Utility Plants (Details) $ in Millions	Dec. 31, 2023 CAD ($)
Jointly Owned Facilities [Line Items]
Cost	$ 2,761
Accumulated Depreciation	(1,043)
Net Book Value	1,718
Transmission Facilities
Jointly Owned Facilities [Line Items]
Cost	1,485
Accumulated Depreciation	(432)
Net Book Value	$ 1,053
Springerville Common Facilities
Jointly Owned Facilities [Line Items]
Ownership (percent)	86.00%
Cost	$ 530
Accumulated Depreciation	(302)
Net Book Value	$ 228
Springerville Coal Handling Facilities
Jointly Owned Facilities [Line Items]
Ownership (percent)	83.00%
Cost	$ 275
Accumulated Depreciation	(136)
Net Book Value	$ 139
Four Corners Units 4 and 5 ("Four Corners")
Jointly Owned Facilities [Line Items]
Ownership (percent)	7.00%
Cost	$ 271
Accumulated Depreciation	(128)
Net Book Value	$ 143
Gila River Common Facilities
Jointly Owned Facilities [Line Items]
Ownership (percent)	50.00%
Cost	$ 119
Accumulated Depreciation	(45)
Net Book Value	$ 74
Luna Energy Facility ("Luna")
Jointly Owned Facilities [Line Items]
Ownership (percent)	33.30%
Cost	$ 81
Accumulated Depreciation	0
Net Book Value	$ 81

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 360
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479960/980-360-S99-1

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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.

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The total period end amount of plant in service and construction in progress net of accumulated depreciation for the utility's share of jointly owned electricity generation plant.

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The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

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The proportionate share of interest (percent) in a jointly owned utility plant.

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