Regulatory Matters - Cost Recovery Mechanisms (Details)																									3 Months Ended	9 Months Ended	12 Months Ended
	Jul. 31, 2024 USD ($)	Jun. 01, 2024 USD ($) MW	May 01, 2024 $ / kWh	Apr. 19, 2024	Nov. 30, 2023 USD ($) $ / kWh	Oct. 25, 2023 USD ($)	Oct. 11, 2023	Jul. 31, 2023 USD ($)	Jul. 01, 2023 USD ($) $ / KWH_Kilowatt_hour	Jun. 01, 2023 USD ($)	May 01, 2023 $ / kWh	Mar. 10, 2023 USD ($)	Feb. 23, 2023 $ / kWh	Feb. 01, 2023 USD ($) $ / kWh	Sep. 23, 2022 MW	Jul. 12, 2022 USD ($) $ / kWh	Jun. 01, 2022 USD ($)	Feb. 15, 2022 USD ($)	Feb. 01, 2022 $ / kWh	Oct. 01, 2021 $ / kWh	Feb. 15, 2021 USD ($)	Feb. 01, 2020 $ / kWh	Oct. 31, 2019 $ / KWH_Kilowatt_hour	Sep. 01, 2017	Mar. 31, 2022 storage	Sep. 30, 2024 USD ($)	Dec. 31, 2023 storage	Dec. 31, 2022 storage	Dec. 31, 2021 storage	Jul. 01, 2024 USD ($)	Apr. 26, 2024 USD ($)	Oct. 27, 2023 USD ($)	Sep. 30, 2023 USD ($)	May 31, 2023 USD ($)	Nov. 30, 2022 USD ($)	Jul. 01, 2022 USD ($)	Apr. 18, 2022 USD ($)	Dec. 17, 2021 USD ($)	Dec. 09, 2021 USD ($)	Jul. 01, 2021 USD ($)
APS
Public Utilities, General Disclosures [Line Items]
Number of energy storage PPA | storage																											9	1	4
Number of energy storage PPA, terminated | storage																									1
Annual amount of approved equity infusions																										$ 150,000,000
Increased in equity contributions																																$ 500,000,000
Public utilities, request to permanently modify permitted yearly equity infusions				2.50%
APS | Damage from Fire, Explosion or Other Hazard
Public Utilities, General Disclosures [Line Items]
Past due balance threshold qualifying for payment extension																																					$ 75
RES | ACC | APS
Public Utilities, General Disclosures [Line Items]
Plan term																										5 years
RES 2018 | ACC | APS
Public Utilities, General Disclosures [Line Items]
Amount of proposed budget																														$ 92,700,000			$ 95,100,000			$ 86,200,000			$ 100,500,000	$ 93,100,000
RES 2018 | ACC | APS | Solar Communities
Public Utilities, General Disclosures [Line Items]
Program term																3 years
RES 2018 | ACC | APS | Minimum
Public Utilities, General Disclosures [Line Items]
Authorized spending																$ 20,000,000
RES 2018 | ACC | APS | Maximum
Public Utilities, General Disclosures [Line Items]
Authorized spending																$ 30,000,000
Retail Rate Case Filing with Arizona Corporation Commission | APS | Maximum
Public Utilities, General Disclosures [Line Items]
Fixed cost recoverable per power lost (in dollars per kWh) | $ / KWH_Kilowatt_hour																							2.68
Retail Rate Case Filing with Arizona Corporation Commission | ACC | APS
Public Utilities, General Disclosures [Line Items]
Commercial customers, market pricing, threshold | MW															140
Demand Side Management Adjustor Charge 2022 | ACC | APS
Public Utilities, General Disclosures [Line Items]
Amount of proposed budget																																						$ 78,400,000
Increase in proposed budget																																						$ 14,000,000
2023 Transportation Electrification Plan | ACC | APS
Public Utilities, General Disclosures [Line Items]
Amount of proposed budget																																			$ 5,000,000
Demand Side Management Adjustor Charge 2023 | ACC | APS
Public Utilities, General Disclosures [Line Items]
Amount of proposed budget																																		$ 88,000,000	$ 88,000,000
Demand Side Management Adjustor Charge 2024 | ACC | APS
Public Utilities, General Disclosures [Line Items]
Amount of proposed budget					$ 91,500,000
Amount of updated budget																															$ 90,900,000
Power Supply Adjustor (PSA) | ACC | APS
Public Utilities, General Disclosures [Line Items]
PSA rate (in dollars per kWh) | $ / kWh					0.019074								0.019074	0.006					0.007544
PSA rate for prior year (in dollars per kWh) | $ / kWh					(0.012624)								(0.005527)						0.004842
Forward component of increase in PSA (in dollars per kWh) | $ / kWh					0.013071								0.013071						0.012386
Transition component of PSA rate | $ / kWh					0.011530								0.011530
Depletion period													24 months
Reporting threshold amount of balancing account					$ 100,000,000
Approved PSA rate | $ / kWh					0.011977
Power Supply Adjustor (PSA) | ACC | APS | Cost Recovery Mechanisms
Public Utilities, General Disclosures [Line Items]
Maximum increase decrease in PSA rate | $ / kWh																						0.006
Historical component of increase in PSA (in dollars per kWh) | $ / kWh																			0.004
Environmental Improvement Surcharge | FERC | APS
Public Utilities, General Disclosures [Line Items]
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
Rate matter, environmental surcharge cap rate amount												$ 4,000,000
Open Access Transmission Tariff | FERC | APS
Public Utilities, General Disclosures [Line Items]
Increase (decrease) in annual wholesale transmission rates		$ 27,400,000								$ 34,700,000							$ (33,000,000)
Rate matters, increase (decrease) in cost recovery, wholesale customer rates		16,600,000								20,700,000							(6,400,000)
Increase (decrease) in retail customer rates		10,800,000								14,000,000							(26,600,000)
Rate matters, increase (decrease) in retail revenue requirements		$ 8,800,000								$ (10,000,000)							$ (2,400,000)
Rate matters, increase in residential and commercial rates (in MW) | MW		3
Rate matters, decrease in commercial rates (in MW) | MW		3
Lost Fixed Cost Recovery Mechanisms | APS
Public Utilities, General Disclosures [Line Items]
Percentage of retail revenues																										1.00%
Fixed cost recoverable per power lost (in dollars per kWh) | $ / KWH_Kilowatt_hour																							2.56
Amount of adjustment representing prorated sales losses pending approval	$ 49,600,000							$ 68,700,000										$ 59,100,000
Increase (decrease) in amount of adjustment representing prorated sales losses																		$ 32,500,000			$ 11,800,000
Amount of adjustment representing annual recovery	$ 8,000,000							$ 9,600,000
Lost Fixed Cost Recovery Mechanisms | ACC
Public Utilities, General Disclosures [Line Items]
Amount of adjustment approved to transfer						$ 27,100,000
Court Resolution Surcharge | ACC | APS
Public Utilities, General Disclosures [Line Items]
Court resolution surcharge (in dollars per kWh) | $ / KWH_Kilowatt_hour									0.00175
Lost revenue recovery									$ 59,600,000
Lost revenue recovery collected																										$ 22,500,000
Net Metering | ACC | APS
Public Utilities, General Disclosures [Line Items]
Cost of service, resource comparison proxy method, maximum annual percentage decrease			10.00%				10.00%				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
Third-year export energy price (in dollars per kWh) | $ / kWh			6.857								0.07619
Rate lock period							10 years