UTILITY PLANT AND JOINTLY-OWNED FACILITIES (Jointly-Owned Facilities) (Details) $ in Millions	Dec. 31, 2021 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Plant in Service	$ 1,883
Construction Work in Progress	27
Accumulated Depreciation	(975)
Net Book Value	$ 935
San Juan Unit 1
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	50.00%
Plant in Service	$ 285
Construction Work in Progress	1
Accumulated Depreciation	(269)
Net Book Value	$ 17
Four Corners Units 4 and 5
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	7.00%
Plant in Service	$ 188
Construction Work in Progress	4
Accumulated Depreciation	(81)
Net Book Value	$ 111
Luna
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	33.30%
Plant in Service	$ 59
Construction Work in Progress	1
Accumulated Depreciation	(3)
Net Book Value	$ 57
Gila River Unit 3
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	75.00%
Plant in Service	$ 206
Construction Work in Progress	0
Accumulated Depreciation	(65)
Net Book Value	$ 141
Gila River Common Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	43.80%
Plant in Service	$ 75
Construction Work in Progress	1
Accumulated Depreciation	(26)
Net Book Value	$ 50
Springerville Coal Handling Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	83.00%
Plant in Service	$ 209
Construction Work in Progress	0
Accumulated Depreciation	(95)
Net Book Value	$ 114
Springerville Common Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Ownership Percentage (in percentage)	86.00%
Plant in Service	$ 399
Construction Work in Progress	0
Accumulated Depreciation	(207)
Net Book Value	192
Transmission Facilities
Public Utility, Property, Plant and Equipment [Line Items]
Plant in Service	462
Construction Work in Progress	20
Accumulated Depreciation	(229)
Net Book Value	$ 253

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-URI http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033

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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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- Definition

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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- Definition

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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