Commitments and Contingencies (Details) (ARIZONA PUBLIC SERVICE COMPANY, USD $)	9 Months Ended
	Sep. 30, 2011 kilovolt minute customer D mW M trust
ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station
Estimated share of the costs related to on-site interim storage of spent nuclear fuel	$ 122,000,000
Regulatory liability of amounts recovered in retail rates in excess of amounts spent for on-site interim spent fuel storage	48,000,000
Maximum insurance against public liability per occurrence for a nuclear incident	12,600,000,000
Maximum available nuclear liability insurance	375,000,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program	12,200,000,000
Maximum assessment per reactor for each nuclear incident	118,000,000
Annual limit per incident with respect to maximum assessment	18,000,000
Number of VIE lessor trusts	3
Maximum potential assessment per incident of APS	103,000,000
Annual payment limitation with respect to maximum potential assessment	15,000,000
Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde	2,750,000,000
Maximum amount that APS could incur under the current NEIL policies for each retrospective assessment	18,000,000
Collateral assurance provided based on rating triggers	$ 46,000,000
Period to provide collateral assurance based on rating triggers (in days)	20