Commitments and Contingencies - Palo Verde Nuclear Generating Station and Contractual Obligations (Details)		3 Months Ended	12 Months Ended
	Aug. 18, 2014 USD ($)	Dec. 31, 2017 USD ($) Trust	Dec. 31, 2017 USD ($) Trust time_period claim	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 1986 Trust
ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
Maximum insurance against public liability per occurrence for a nuclear incident			$ 13,400,000,000.0
Maximum available nuclear liability insurance			450,000,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program			13,000,000,000
Maximum assessment per reactor for each nuclear incident			127,300,000
Annual limit per incident with respect to maximum assessment			$ 19,000,000
Number of VIE lessor trusts | Trust		3	3			3
Maximum potential retrospective assessment per incident of APS			$ 111,100,000
Annual payment limitation with respect to maximum potential retrospective assessment			16,600,000
Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde			2,800,000,000
Maximum amount that APS could incur under the current NEIL policies for each retrospective assessment			24,000,000
Collateral assurance provided based on rating triggers			$ 64,800,000
Period to provide collateral assurance based on rating triggers			20 days
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2018		$ 715,000,000	$ 715,000,000
2019		578,000,000	578,000,000
2020		548,000,000	548,000,000
2021		548,000,000	548,000,000
2022		554,000,000	554,000,000
Thereafter		6,500,000,000	6,500,000,000
ARIZONA PUBLIC SERVICE COMPANY | Coal take-or-pay commitments
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2018		159,997,000	159,997,000
2019		185,365,000	185,365,000
2020		186,632,000	186,632,000
2021		190,607,000	190,607,000
2022		194,678,000	194,678,000
Thereafter		1,750,739,000	1,750,739,000
Total obligation		2,668,018,000	2,668,018,000
Present value of commitments		1,900,000,000	1,900,000,000
Total purchases			165,220,000	$ 160,066,000	$ 211,327,000
ARIZONA PUBLIC SERVICE COMPANY | Renewable energy credits
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2018		40,000,000	40,000,000
2019		40,000,000	40,000,000
2020		40,000,000	40,000,000
2021		40,000,000	40,000,000
2022		40,000,000	40,000,000
Thereafter		370,000,000	370,000,000
ARIZONA PUBLIC SERVICE COMPANY | Coal Mine Reclamation Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2018		31,000,000	31,000,000
2019		32,000,000	32,000,000
2020		21,000,000	21,000,000
2021		20,000,000	20,000,000
2022		22,000,000	22,000,000
Thereafter		191,000,000	191,000,000
ARIZONA PUBLIC SERVICE COMPANY | Coal Mine Reclamation Balance Sheet Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
Total obligation		216,000,000	216,000,000	207,000,000
4CA | Coal Mine Reclamation Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2018		1,000,000	1,000,000
2019		1,000,000	1,000,000
2020		2,000,000	2,000,000
2021		2,000,000	2,000,000
2022		2,000,000	2,000,000
Thereafter		16,000,000	16,000,000
4CA | Coal Mine Reclamation Balance Sheet Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
Total obligation		16,000,000	16,000,000	$ 15,000,000
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal
Palo Verde Nuclear Generating Station [Abstract]
Settlement amount, awarded to company	$ 57,400,000	9,000,000
Proceeds from legal settlements			$ 65,200,000
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal | ARIZONA PUBLIC SERVICE COMPANY
Palo Verde Nuclear Generating Station [Abstract]
Settlement amount, awarded to company	$ 16,700,000	$ 2,600,000
New claims filed | claim			3
Number of settlement agreement time periods | time_period			3
Proceeds from legal settlements			$ 19,000,000