Jointly-Owned Facilities (Details) - APS $ in Thousands	Dec. 31, 2025 USD ($)
Palo Verde Units 1 and 3
Interests in jointly-owned facilities
Percent Owned	29.10%
Plant in Service	$ 2,094,060
Accumulated Depreciation	1,079,823
Construction Work in Progress	$ 13,230
Palo Verde Unit 2
Interests in jointly-owned facilities
Percent Owned	23.90%
Plant in Service	$ 925,562
Accumulated Depreciation	567,731
Construction Work in Progress	$ 7,343
Palo Verde Common
Interests in jointly-owned facilities
Percent Owned	26.20%
Plant in Service	$ 977,526
Accumulated Depreciation	431,023
Construction Work in Progress	58,899
Palo Verde sale leaseback
Interests in jointly-owned facilities
Plant in Service	142,921
Accumulated Depreciation	110,886
Construction Work in Progress	$ 0
Four Corners Generating Station
Interests in jointly-owned facilities
Percent Owned	63.00%
Plant in Service	$ 1,941,053
Accumulated Depreciation	747,931
Construction Work in Progress	$ 19,378
Arizona Nuclear Power Project 500kV System
Interests in jointly-owned facilities
Percent Owned	33.10%
Plant in Service	$ 141,348
Accumulated Depreciation	60,579
Construction Work in Progress	$ 5,350
Navajo Southern System
Interests in jointly-owned facilities
Percent Owned	25.10%
Plant in Service	$ 89,856
Accumulated Depreciation	40,548
Construction Work in Progress	$ 1,645
Palo Verde — Yuma 500kV System
Interests in jointly-owned facilities
Percent Owned	16.10%
Plant in Service	$ 44,505
Accumulated Depreciation	9,060
Construction Work in Progress	$ 136
Four Corners Switchyards
Interests in jointly-owned facilities
Percent Owned	56.90%
Plant in Service	$ 86,706
Accumulated Depreciation	25,810
Construction Work in Progress	$ 118
Phoenix — Mead System
Interests in jointly-owned facilities
Percent Owned	17.50%
Plant in Service	$ 36,290
Accumulated Depreciation	19,568
Construction Work in Progress	$ 609
Palo Verde — Rudd 500kV System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 96,428
Accumulated Depreciation	35,842
Construction Work in Progress	$ 3,343
Morgan — Pinnacle Peak System
Interests in jointly-owned facilities
Percent Owned	63.20%
Plant in Service	$ 119,104
Accumulated Depreciation	31,283
Construction Work in Progress	$ 75
Round Valley System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 548
Accumulated Depreciation	224
Construction Work in Progress	$ 0
Palo Verde — Morgan System
Interests in jointly-owned facilities
Percent Owned	87.50%
Plant in Service	$ 268,202
Accumulated Depreciation	52,822
Construction Work in Progress	$ 392
Hassayampa — North Gila System
Interests in jointly-owned facilities
Percent Owned	80.00%
Plant in Service	$ 154,329
Accumulated Depreciation	31,361
Construction Work in Progress	$ 0
Cholla 500kV Switchyard
Interests in jointly-owned facilities
Percent Owned	85.70%
Plant in Service	$ 8,456
Accumulated Depreciation	3,114
Construction Work in Progress	$ 190
Saguaro 500kV Switchyard
Interests in jointly-owned facilities
Percent Owned	60.00%
Plant in Service	$ 42,795
Accumulated Depreciation	16,324
Construction Work in Progress	$ 800
Kyrene — Knox System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 578
Accumulated Depreciation	359
Construction Work in Progress	$ 0