UTILITY PLANT AND JOINTLY-OWNED FACILITIES (Jointly-Owned Facilities) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Plant in Service	$ 1,718
Construction Work in Progress	46
Accumulated Depreciation	(756)
Net Book Value	$ 1,008
Four Corners Units 4 and 5
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage	7.00%
Plant in Service	$ 201
Construction Work in Progress	4
Accumulated Depreciation	(97)
Net Book Value	$ 108
Luna
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage	33.30%
Plant in Service	$ 58
Construction Work in Progress	3
Accumulated Depreciation	0
Net Book Value	$ 61
Gila River Unit 3
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage	75.00%
Plant in Service	$ 218
Construction Work in Progress	17
Accumulated Depreciation	(62)
Net Book Value	$ 173
Gila River Common Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage	43.80%
Plant in Service	$ 78
Construction Work in Progress	1
Accumulated Depreciation	(30)
Net Book Value	$ 49
Springerville Coal Handling Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage	83.00%
Plant in Service	$ 208
Construction Work in Progress	0
Accumulated Depreciation	(103)
Net Book Value	$ 105
Springerville Common Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage	86.00%
Plant in Service	$ 400
Construction Work in Progress	0
Accumulated Depreciation	(228)
Net Book Value	172
Transmission Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Plant in Service	555
Construction Work in Progress	21
Accumulated Depreciation	(236)
Net Book Value	$ 340

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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- Definition

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 construction work in progress at a jointly owned electricity generation plant.

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- Definition

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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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

No definition available.

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