Jointly-Owned Facilities (Details) - ARIZONA PUBLIC SERVICE COMPANY $ in Thousands	Dec. 31, 2020 USD ($)
Palo Verde Units 1 and 3
Interests in jointly-owned facilities
Percent owned	29.10%
Plant in service	$ 1,911,339
Accumulated depreciation	1,108,883
Construction work in progress	$ 26,623
Palo Verde Unit 2
Interests in jointly-owned facilities
Percent owned	16.80%
Plant in service	$ 649,035
Accumulated depreciation	379,305
Construction work in progress	$ 7,268
Palo Verde Common
Interests in jointly-owned facilities
Percent owned	28.00%
Plant in service	$ 774,054
Accumulated depreciation	320,107
Construction work in progress	41,607
Palo Verde Sale Leaseback
Interests in jointly-owned facilities
Plant in service	351,050
Accumulated depreciation	253,014
Construction work in progress	$ 0
Four Corners Generating Station
Interests in jointly-owned facilities
Percent owned	63.00%
Plant in service	$ 1,621,418
Accumulated depreciation	581,436
Construction work in progress	$ 35,028
Cholla Common Facilities
Interests in jointly-owned facilities
Percent owned	50.50%
Plant in service	$ 193,807
Accumulated depreciation	109,447
Construction work in progress	$ 1,206
ANPP 500kV System
Interests in jointly-owned facilities
Percent owned	33.50%
Plant in service	$ 131,991
Accumulated depreciation	52,626
Construction work in progress	$ 3,859
Navajo Southern System
Interests in jointly-owned facilities
Percent owned	26.00%
Plant in service	$ 89,113
Accumulated depreciation	33,536
Construction work in progress	$ 1,215
Palo Verde — Yuma 500kV System
Interests in jointly-owned facilities
Percent owned	25.30%
Plant in service	$ 23,247
Accumulated depreciation	6,681
Construction work in progress	$ 433
Four Corners Switchyards
Interests in jointly-owned facilities
Percent owned	61.80%
Plant in service	$ 69,441
Accumulated depreciation	17,009
Construction work in progress	$ 3,145
Phoenix — Mead System
Interests in jointly-owned facilities
Percent owned	17.10%
Plant in service	$ 39,437
Accumulated depreciation	19,072
Construction work in progress	$ 73
Palo Verde — Rudd 500kV System
Interests in jointly-owned facilities
Percent owned	50.00%
Plant in service	$ 93,123
Accumulated depreciation	28,206
Construction work in progress	$ 1,921
Morgan — Pinnacle Peak System
Interests in jointly-owned facilities
Percent owned	64.60%
Plant in service	$ 117,497
Accumulated depreciation	20,754
Construction work in progress	$ 912
Round Valley System
Interests in jointly-owned facilities
Percent owned	50.00%
Plant in service	$ 531
Accumulated depreciation	174
Construction work in progress	$ 13
Palo Verde — Morgan System
Interests in jointly-owned facilities
Percent owned	88.90%
Plant in service	$ 257,220
Accumulated depreciation	20,943
Construction work in progress	$ 530
Hassayampa — North Gila System
Interests in jointly-owned facilities
Percent owned	80.00%
Plant in service	$ 148,067
Accumulated depreciation	16,080
Construction work in progress	$ 0
Cholla 500kV Switchyard
Interests in jointly-owned facilities
Percent owned	85.70%
Plant in service	$ 7,896
Accumulated depreciation	1,850
Construction work in progress	$ 940
Saguaro 500kV Switchyard
Interests in jointly-owned facilities
Percent owned	60.00%
Plant in service	$ 21,669
Accumulated depreciation	13,229
Construction work in progress	$ 2
Kyrene — Knox System
Interests in jointly-owned facilities
Percent owned	50.00%
Plant in service	$ 578
Accumulated depreciation	323
Construction work in progress	$ 0