Commitments and Contingencies - Palo Verde Nuclear Generating Station and Contractual Obligations (Details) (USD $)	3 Months Ended	0 Months Ended		3 Months Ended
	Mar. 31, 2015 power_plant	Mar. 11, 2015	Aug. 18, 2014	Jun. 30, 2015	Dec. 31, 1986 Trust
Arizona Public Service Company
Palo Verde Nuclear Generating Station
Maximum insurance against public liability per occurrence for a nuclear incident	$ 13,600,000,000
Maximum available nuclear liability insurance	375,000,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program	13,200,000,000
Maximum retrospective premium assessment per reactor for each nuclear liability incident	127,300,000
Annual limit per incident with respect to maximum retrospective premium assessment	19,000,000
Number of VIE lessor trusts	3				3
Maximum potential retrospective assessment per incident of APS	111,000,000
Annual payment limitation with respect to maximum potential retrospective premium assessment	16,500,000
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	23,000,000
Collateral assurance provided based on rating triggers	62,000,000
Period to provide collateral assurance based on rating triggers	20 days
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste
Palo Verde Nuclear Generating Station
Litigation settlement amount		42,000,000	57,400,000
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste | Arizona Public Service Company
Palo Verde Nuclear Generating Station
Litigation settlement amount		12,200,000	16,700,000
Regulatory Liability | Forecast | Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste | Arizona Public Service Company
Palo Verde Nuclear Generating Station
Proceeds from legal settlements				$ 12,200,000