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Jointly Owned Utility Facilities - NPC (Details)
$ in Millions
Dec. 31, 2022
USD ($)
Jointly Owned Utility Plant Interests [Line Items]  
Facility in service $ 10,587
Accumulated depreciation 5,879
Construction work in progress 272
NPC  
Jointly Owned Utility Plant Interests [Line Items]  
Facility in service 178
Accumulated depreciation 57
Construction work in progress $ 1
NPC | Navajo  
Jointly Owned Utility Plant Interests [Line Items]  
Ownership share 11.00%
Facility in service $ 1
Accumulated depreciation 4
Construction work in progress $ 0
NPC | Other  
Jointly Owned Utility Plant Interests [Line Items]  
Ownership share 19.00%
Facility in service $ 121
Accumulated depreciation 26
Construction work in progress 1
NPC | Other transmission facilities  
Jointly Owned Utility Plant Interests [Line Items]  
Facility in service 56
Accumulated depreciation 27
Construction work in progress $ 0