Jointly-Owned Facilities (Details) (ARIZONA PUBLIC SERVICE COMPANY, USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Palo Verde Units 1 and 3
Interests in jointly-owned facilities
Percent Owned	29.10%
Plant in Service	$ 2,061,894
Accumulated Depreciation	1,154,141
Construction Work in Progress	66,558
Palo Verde Unit 2
Interests in jointly-owned facilities
Percent Owned	17.00%
Plant in Service	661,006
Accumulated Depreciation	365,704
Construction Work in Progress	33,032
Palo Verde Sale Leaseback
Interests in jointly-owned facilities
Plant in Service	351,050
Accumulated Depreciation	218,186
Four Corners Units 4 and 5
Interests in jointly-owned facilities
Percent Owned	15.00%
Plant in Service	165,139
Accumulated Depreciation	104,910
Construction Work in Progress	2,357
Four Corners common
Interests in jointly-owned facilities
Percent Owned	38.44%
Plant in Service	16,413
Accumulated Depreciation	5,997
Construction Work in Progress	750
Navajo Generating Station Units 1, 2 and 3
Interests in jointly-owned facilities
Percent Owned	14.00%
Plant in Service	264,227
Accumulated Depreciation	170,777
Construction Work in Progress	10,327
Cholla common facilities
Interests in jointly-owned facilities
Percent Owned	63.30%
Plant in Service	146,642
Accumulated Depreciation	51,985
Construction Work in Progress	1,661
ANPP 500kV System
Interests in jointly-owned facilities
Percent Owned	33.00%
Plant in Service	88,451
Accumulated Depreciation	30,123
Construction Work in Progress	10,161
Navajo Southern System
Interests in jointly-owned facilities
Percent Owned	25.90%
Plant in Service	51,174
Accumulated Depreciation	15,161
Construction Work in Progress	920
Palo Verde - Yuma 500kV System
Interests in jointly-owned facilities
Percent Owned	44.10%
Plant in Service	8,816
Accumulated Depreciation	4,331
Four Corners Switchyards
Interests in jointly-owned facilities
Percent Owned	39.60%
Plant in Service	19,630
Accumulated Depreciation	5,696
Construction Work in Progress	1,004
Phoenix - Mead System
Interests in jointly-owned facilities
Percent Owned	17.50%
Plant in Service	39,374
Accumulated Depreciation	10,731
Palo Verde - Estrella 500kV System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	85,643
Accumulated Depreciation	11,769
Construction Work in Progress	3,445
North Valley System
Interests in jointly-owned facilities
Percent Owned	69.30%
Plant in Service	95,057
Accumulated Depreciation	1,757
Construction Work in Progress	3,821
Round Valley System
Interests in jointly-owned facilities
Percent Owned	50.00%
Plant in Service	570
Accumulated Depreciation	$ 320