Jointly-Owned Facilities (Details) (ARIZONA PUBLIC SERVICE COMPANY, USD $)	Dec. 31, 2012
Palo Verde Units 1 and 3
Interests in jointly-owned facilities
Percent Owned	29.10%
Plant in Service	$ 1,717,970,000
Accumulated Depreciation	1,006,615,000
Construction Work in Progress	15,122,000
Palo Verde Unit 2
Interests in jointly-owned facilities
Percent Owned	16.80%
Plant in Service	555,132,000
Accumulated Depreciation	324,063,000
Construction Work in Progress	4,125,000
Palo Verde Common
Interests in jointly-owned facilities
Percent Owned	28.00%
Plant in Service	516,950,000
Accumulated Depreciation	223,632,000
Construction Work in Progress	83,365,000
Palo Verde Sale Leaseback
Interests in jointly-owned facilities
Plant in Service	351,050,000
Accumulated Depreciation	222,055,000
Four Corners Units 4 and 5
Interests in jointly-owned facilities
Percent Owned	15.00%
Plant in Service	167,390,000
Accumulated Depreciation	36,311,000
Construction Work in Progress	3,040,000
Four Corners Common
Interests in jointly-owned facilities
Percent Owned	38.40%
Plant in Service	58,810,000
Accumulated Depreciation	17,930,000
Construction Work in Progress	1,512,000
Navajo Generating Station Units 1, 2 and 3
Interests in jointly-owned facilities
Percent Owned	14.00%
Plant in Service	269,792,000
Accumulated Depreciation	141,914,000
Construction Work in Progress	2,368,000
Cholla common facilities
Interests in jointly-owned facilities
Percent Owned	63.30%
Plant in Service	146,571,000
Accumulated Depreciation	43,815,000
Construction Work in Progress	1,680,000
ANPP 500kV System
Interests in jointly-owned facilities
Percent Owned	33.30%
Plant in Service	82,490,000
Accumulated Depreciation	31,511,000
Construction Work in Progress	1,607,000
Navajo Southern System
Interests in jointly-owned facilities
Percent Owned	22.20%
Plant in Service	55,427,000
Accumulated Depreciation	15,815,000
Construction Work in Progress	561,000
Palo Verde - Yuma 500kV System
Interests in jointly-owned facilities
Percent Owned	18.30%
Plant in Service	11,761,000
Accumulated Depreciation	4,493,000
Construction Work in Progress	797,000
Morgan-Pinnacle Peak System
Interests in jointly-owned facilities
Percent Owned	64.10%
Plant in Service	133,073,000
Accumulated Depreciation	3,751,000
Construction Work in Progress	331,000
Four Corners Switchyards
Interests in jointly-owned facilities
Percent Owned	37.00%
Plant in Service	20,874,000
Accumulated Depreciation	6,033,000
Construction Work in Progress	1,466,000
Phoenix - Mead System
Interests in jointly-owned facilities
Percent Owned	17.10%
Plant in Service	39,772,000
Accumulated Depreciation	11,553,000
Palo Verde - Estrella 500kV System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	85,643,000
Accumulated Depreciation	13,309,000
Construction Work in Progress	4,137,000
Round Valley System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	488,000
Accumulated Depreciation	$ 261,000