Jointly-Owned Facilities (Details) - ARIZONA PUBLIC SERVICE COMPANY $ in Thousands	Dec. 31, 2019 USD ($)
Palo Verde Units 1 and 3
Interests in jointly-owned facilities
Percent Owned	29.10%
Plant in Service	$ 1,877,748
Accumulated Depreciation	1,102,609
Construction work in progress	$ 22,071
Palo Verde Unit 2
Interests in jointly-owned facilities
Percent Owned	16.80%
Plant in Service	$ 634,545
Accumulated Depreciation	377,722
Construction work in progress	$ 11,831
Palo Verde Common
Interests in jointly-owned facilities
Percent Owned	28.00%
Plant in Service	$ 746,653
Accumulated Depreciation	290,084
Construction work in progress	46,570
Palo Verde Sale Leaseback
Interests in jointly-owned facilities
Plant in Service	351,050
Accumulated Depreciation	249,144
Construction work in progress	$ 0
Four Corners Generating Station
Interests in jointly-owned facilities
Percent Owned	63.00%
Plant in Service	$ 1,520,171
Accumulated Depreciation	559,272
Construction work in progress	$ 44,842
Cholla Common Facilities
Interests in jointly-owned facilities
Percent Owned	50.50%
Plant in Service	$ 184,608
Accumulated Depreciation	95,720
Construction work in progress	$ 1,323
ANPP 500kV System
Interests in jointly-owned facilities
Percent Owned	33.50%
Plant in Service	$ 133,396
Accumulated Depreciation	51,248
Construction work in progress	$ 2,723
Navajo Southern System
Interests in jointly-owned facilities
Percent Owned	26.70%
Plant in Service	$ 89,672
Accumulated Depreciation	31,985
Construction work in progress	$ 194
Palo Verde — Yuma 500kV System
Interests in jointly-owned facilities
Percent Owned	19.00%
Plant in Service	$ 15,274
Accumulated Depreciation	6,486
Construction work in progress	$ 4,886
Four Corners Switchyards
Interests in jointly-owned facilities
Percent Owned	63.00%
Plant in Service	$ 69,994
Accumulated Depreciation	16,674
Construction work in progress	$ 2,395
Phoenix — Mead System
Interests in jointly-owned facilities
Percent Owned	17.10%
Plant in Service	$ 39,355
Accumulated Depreciation	18,570
Construction work in progress	$ 53
Palo Verde — Rudd 500kV System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 93,112
Accumulated Depreciation	26,719
Construction work in progress	$ 317
Morgan — Pinnacle Peak System
Interests in jointly-owned facilities
Percent Owned	64.60%
Plant in Service	$ 117,752
Accumulated Depreciation	18,822
Construction work in progress	$ 0
Round Valley System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 515
Accumulated Depreciation	164
Construction work in progress	$ 0
Palo Verde — Morgan System
Interests in jointly-owned facilities
Percent Owned	88.90%
Plant in Service	$ 238,689
Accumulated Depreciation	13,146
Construction work in progress	$ 0
Hassayampa — North Gila System
Interests in jointly-owned facilities
Percent Owned	80.00%
Plant in Service	$ 143,422
Accumulated Depreciation	12,676
Construction work in progress	$ 0
Cholla 500kV Switchyard
Interests in jointly-owned facilities
Percent Owned	85.70%
Plant in Service	$ 7,651
Accumulated Depreciation	1,597
Construction work in progress	$ 535
Saguaro 500kV Switchyard
Interests in jointly-owned facilities
Percent Owned	60.00%
Plant in Service	$ 20,425
Accumulated Depreciation	12,949
Construction work in progress	$ 0
Kyrene — Knox System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	$ 578
Accumulated Depreciation	315
Construction work in progress	$ 0