Regulatory Matters - Cost Recovery Mechanisms (Details)																																1 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Oct. 11, 2023	Jul. 31, 2023 USD ($)	Jul. 01, 2023 USD ($) $ / KWH_Kilowatt_hour	May 01, 2023 $ / kWh	Mar. 10, 2023 USD ($)	Feb. 23, 2023 USD ($) $ / kWh	Feb. 01, 2023 USD ($) $ / kWh	Jan. 06, 2023 USD ($)	Sep. 23, 2022 MW	Jul. 12, 2022 USD ($) $ / kWh	Jun. 01, 2022 USD ($)	Feb. 15, 2022 USD ($)	Feb. 01, 2022 USD ($) $ / kWh $ / KWH_Kilowatt_hour	Nov. 01, 2021 $ / kWh	Oct. 01, 2021 $ / kWh	Jun. 07, 2021 USD ($)	Jun. 01, 2021 USD ($)	Apr. 01, 2021 $ / kWh	Feb. 15, 2021 USD ($)	Feb. 01, 2021 USD ($) $ / kWh	Aug. 20, 2020 USD ($) customer	Jul. 01, 2020 USD ($)	May 01, 2020 $ / kWh	Feb. 01, 2020 $ / kWh	Nov. 14, 2019 USD ($) customer	Oct. 31, 2019 $ / KWH_Kilowatt_hour	Oct. 29, 2019 USD ($)	May 01, 2019 $ / kWh	Apr. 10, 2019	Aug. 13, 2018 USD ($)	Sep. 01, 2017	Mar. 31, 2021	Jun. 30, 2021 program MW	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2017 $ / kWh	Dec. 31, 2017 $ / KWH_Kilowatt_hour	Oct. 27, 2023 USD ($)	Jun. 30, 2023 USD ($)	May 31, 2023 USD ($)	Nov. 30, 2022 USD ($)	Jul. 01, 2022 USD ($)	Apr. 18, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 17, 2021 USD ($)	Dec. 09, 2021 USD ($)	Jul. 01, 2021 USD ($)	Dec. 31, 2020 USD ($)	May 15, 2020 USD ($)	May 05, 2020 USD ($)	Dec. 31, 2019 USD ($)
Change in regulatory asset
Deferred fuel and purchased power costs — current period																																		$ 486,382,000	$ 228,483,000
Amounts charged to customers																																		(420,277,000)	(171,607,000)
Rate plan comparison tool, number of customers | customer																					3,800				13,000
Rate plan comparison tool, inconvenience payment																					$ 25				$ 25
APS
Settlement Agreement
Demand side management funds																																																		$ 36,000,000
Customer credits																																												$ 43,000,000
Customer credits, additional funds																																												$ 7,000,000
Change in regulatory asset
Deferred fuel and purchased power costs — current period																																		486,382,000	228,483,000
Amounts charged to customers																																		(420,277,000)	(171,607,000)
Percentage increase under PSA effective for first billing cycle beginning April 2021																																50.00%
Remaining percentage increase under PSA effective for first billing cycle beginning November 2021																																50.00%
Annual amount of approved equity infusions																																		$ 150,000,000
APS | Subsequent Event
Change in regulatory asset
Increased in equity contributions																																						$ 500,000,000
Lost Fixed Cost Recovery Mechanisms | APS
Change in regulatory asset
Fixed cost recoverable per power lost (in dollars per kWh)																																				0.025	2.56
Percentage of retail revenues																																		1.00%
Amount of adjustment representing prorated sales losses pending approval		$ 68,700,000										$ 59,100,000							$ 38,500,000
Increase (decrease) in amount of adjustment representing prorated sales losses												$ 32,500,000							$ 11,800,000
Amount of adjustment representing annual recovery		$ 9,600,000
Maximum | Retail Rate Case Filing with Arizona Corporation Commission | APS
Change in regulatory asset
Fixed cost recoverable per power lost (in dollars per kWh) | $ / KWH_Kilowatt_hour																										2.68
Damage from Fire, Explosion or Other Hazard | APS
Change in regulatory asset
Past due balance threshold qualifying for payment extension																																											$ 75
ACC | APS
Settlement Agreement
Program term																																	18 years
Change in regulatory asset
Amount requested to be returned in form of tax savings to customers																														$ 86,500,000
Deferred taxes amortization, period																													28 years 6 months
Public Utilities, one-time bill credit																											$ 64,000,000
Public Utilities, one-time bill credit, additional benefit																											$ 39,500,000
Number of programs | program																																	2
Solar capacity (in MW) | MW																																	80
ACC | RES | APS
Settlement Agreement
Plan term																																		5 years
ACC | RES 2018 | APS
Settlement Agreement
Amount of proposed budget																						$ 84,700,000																	$ 95,100,000			$ 86,200,000				$ 100,500,000	$ 93,100,000
Revenue requirements																						$ 4,500,000
Authorized amount to be collected																$ 68,300,000
ACC | RES 2018 | APS | Solar Communities
Settlement Agreement
Program term										3 years												3 years
ACC | Retail Rate Case Filing with Arizona Corporation Commission | APS
Settlement Agreement
Commercial customers, market pricing, threshold | MW									140
ACC | Demand Side Management Adjustor Charge 2020 | APS
Settlement Agreement
Amount of proposed budget																																																	$ 51,900,000		$ 51,900,000
ACC | Net Metering | APS
Change in regulatory asset
Cost of service, resource comparison proxy method, maximum annual percentage decrease				10.00%						10.00%																					10.00%
Cost of service for interconnected DG system customers, grandfathered period																															20 years
Cost of service for new customers, guaranteed export price period																															10 years
Second-year export energy price (in dollars per kWh) | $ / kWh										0.0846					0.094								0.094					0.105
Third-year export energy price (in dollars per kWh) | $ / kWh				7.619
ACC | Net Metering | APS | Subsequent Event
Change in regulatory asset
Cost of service, resource comparison proxy method, maximum annual percentage decrease	10.00%
Cost of service, resource comparison proxy method, maximum annual percentage decrease	10 years
ACC | Demand Side Management Adjustor Charge 2021 | APS
Settlement Agreement
Amount of proposed budget																																																$ 63,700,000
ACC | Demand Side Management Adjustor Charge 2022 | APS
Settlement Agreement
Amount of proposed budget																																													$ 78,400,000
Increase in proposed budget																																													$ 14,000,000
ACC | Power Supply Adjustor (PSA) | APS
Change in regulatory asset
Beginning balance																																		$ 460,561,000	388,148,000
Deferred fuel and purchased power costs — current period																																		486,382,000	228,483,000
Amounts charged to customers																																		(420,277,000)	(171,606,000)
Ending balance																																		$ 526,666,000	$ 445,025,000
PSA rate (in dollars per kWh) | $ / kWh						0.019074	0.006						0.007544	0.003544				0.001544		0.003544
PSA rate for prior year (in dollars per kWh) | $ / kWh						(0.005527)							0.004842	(0.004444)				(0.004444)		0.003434
Forward component of increase in PSA (in dollars per kWh) | $ / kWh						0.013071							0.012386	0.007988				0.005988		0.000110
Fuel and purchased power costs above annual cap																				$ 215,900,000
Transition component of PSA rate | $ / kWh						0.011530
Depletion period						24 months
Reporting threshold amount of balancing account						$ 500,000
ACC | Demand Side Management Adjustor Charge 2023 | APS
Settlement Agreement
Amount of proposed budget																																								$ 88,000,000	$ 88,000,000
ACC | Court Resolution Surcharge | APS
Change in regulatory asset
Court resolution surcharge (in dollars per kWh) | $ / KWH_Kilowatt_hour			0.00175
Lost revenue recovery			$ 59,600,000
ACC | Cost Recovery Mechanisms | Power Supply Adjustor (PSA) | APS
Settlement Agreement
Maximum increase decrease in PSA rate | $ / kWh																								0.004
Change in regulatory asset
Historical component of increase in PSA (in dollars per kWh) | $ / kWh													0.004							0.004
ACC | Minimum | RES 2018 | APS
Settlement Agreement
Authorized spending										$ 20,000,000
ACC | Minimum | RES 2018 | APS | Solar Communities
Settlement Agreement
Required annual capital investment																						$ 10,000,000
ACC | Maximum | RES 2018 | APS
Settlement Agreement
Authorized spending										$ 30,000,000
ACC | Maximum | RES 2018 | APS | Solar Communities
Settlement Agreement
Required annual capital investment																						$ 15,000,000
FERC | Environmental Improvement Surcharge | APS
Change in regulatory asset
Rate matter, environmental surcharge cap rate (in dollars per kWh) | $ / KWH_Kilowatt_hour													0.0005
Rate matter, environmental surcharge cap rate amount					$ 4,000,000
Increase (decrease) in annual wholesale transmission rates					(10,700,000)		$ 14,700,000
Rate matters, increase (decrease) in cost recovery, excess of annual amount					$ (7,500,000)		$ 3,300,000
FERC | Open Access Transmission Tariff | APS
Change in regulatory asset
Increase (decrease) in annual wholesale transmission rates								$ 34,700,000			$ (33,000,000)						$ 4,000,000
Decrease in wholesale customer rates								20,700,000			6,400,000						3,200,000
Increase (decrease) in retail customer rates								14,000,000			(26,600,000)						7,200,000
Decreases in retail revenue requirement								$ 10,000,000			$ 2,400,000						$ 28,400,000
FERC | Minimum | Environmental Improvement Surcharge | APS
Change in regulatory asset
Rate matter, environmental surcharge cap rate amount													$ 13,000,000
FERC | Maximum | Environmental Improvement Surcharge | APS
Change in regulatory asset
Rate matter, environmental surcharge cap rate amount													$ 15,000,000