Regulatory Matters - Cost Recovery Mechanisms (Details)																														1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 29, 2022 $ / kWh	Feb. 15, 2022 USD ($)	Feb. 01, 2022 USD ($) $ / kWh	Nov. 01, 2021 $ / kWh	Oct. 01, 2021 $ / kWh	Jul. 01, 2021 USD ($)	Jun. 07, 2021 USD ($)	Jun. 01, 2021 USD ($)	Apr. 01, 2021 USD ($) $ / kWh	Feb. 22, 2021 USD ($)	Feb. 15, 2021 USD ($)	Feb. 01, 2021 USD ($) $ / kWh	Aug. 20, 2020 USD ($) customer	Jun. 01, 2020 USD ($)	May 01, 2020 $ / kWh	Feb. 14, 2020 USD ($)	Feb. 01, 2020 $ / kWh	Nov. 14, 2019 USD ($) customer	Oct. 31, 2019 USD ($) $ / kWh	Oct. 29, 2019 USD ($)	Jun. 01, 2019 USD ($)	May 01, 2019 $ / kWh	Apr. 10, 2019	Feb. 15, 2019 USD ($)	Feb. 01, 2019 $ / kWh	Aug. 13, 2018 USD ($)	Feb. 01, 2018 $ / kWh	Nov. 20, 2017 USD ($)	Sep. 01, 2017 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) program MW	Dec. 31, 2017 $ / kWh	Dec. 17, 2021 USD ($)	Dec. 09, 2021 USD ($)	Jul. 01, 2020 USD ($)	May 15, 2020 USD ($)	May 05, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 01, 2019 USD ($)	Mar. 15, 2019 agreement	Dec. 31, 2018 USD ($)	Nov. 14, 2017 USD ($)
Change in regulatory asset
Deferred fuel and purchased power costs — current period																															$ 6,110,000	$ 52,210,000
Amounts (charged) refunded to customers																															(39,442,000)	564,000
Rate plan comparison tool, number of customers | customer													3,800					13,000
Rate plan comparison tool, inconvenience payment													$ 25					$ 25
APS
Change in regulatory asset
Deferred fuel and purchased power costs — current period																															6,110,000	52,210,000
Amounts (charged) refunded to customers																															(39,442,000)	564,000
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%
Demand side management funds																																							$ 36,000,000
Customer credits																															43,000,000
Customer credits, additional funds																															$ 7,000,000
APS | 2017 Settlement Agreement and its Customer Education and Outreach Plan
Change in regulatory asset
Settlement amount										$ 24,750,000
Settlement amount returned to customers										$ 24,000,000
Lost Fixed Cost Recovery Mechanisms | APS
Change in regulatory asset
Fixed cost recoverable per power lost (in dollars per kWh) | $ / kWh																																		0.025
Percentage of retail revenues																															1.00%
Amount of adjustment representing prorated sales losses pending approval		$ 59,100,000									$ 38,500,000					$ 26,600,000								$ 36,200,000
Increase (decrease) in amount of adjustment representing prorated sales losses		$ 32,500,000									$ 11,800,000					$ (9,600,000)								$ (24,500,000)
ACC | APS
Settlement Agreement
Program term																																	18 years
Change in regulatory asset
Gross-up for revenue requirement of rate regulation																			$ (184,000,000)							$ 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						$ 93,100,000																														$ 100,500,000	$ 84,700,000				$ 86,300,000
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
ACC | Demand Side Management Adjustor Charge 2018 | APS
Settlement Agreement
Amount of proposed budget																													$ 52,600,000															$ 52,600,000
ACC | Demand Side Management Adjustor Charge 2019 | APS
Settlement Agreement
Amount of proposed budget																																											$ 34,100,000
ACC | Demand Side Management Adjustor Charge 2020 | APS
Settlement Agreement
Amount of proposed budget																																						$ 51,900,000		$ 51,900,000
ACC | Power Supply Adjustor (PSA) | APS
Change in regulatory asset
Beginning balance									$ 228,609,000																						$ 388,148,000	175,835,000
Deferred fuel and purchased power costs — current period																															6,110,000	52,210,000
Amounts (charged) refunded to customers																															(39,442,000)	564,000
Ending balance																														$ 228,609,000	$ 354,816,000	$ 228,609,000	$ 175,835,000
PSA rate (in dollars per kWh) | $ / kWh			0.007544	0.003544					0.001544			0.003544					(0.000456)								0.001658		0.004555
PSA rate for prior year (in dollars per kWh) | $ / kWh			(0.004842)	(0.004444)					(0.004444)			0.003434					(0.002086)								0.000536
Forward component of increase in PSA (in dollars per kWh) | $ / kWh			0.012386	0.007988					0.005988			0.000110					0.001630								0.001122
Fuel and purchased power costs above annual cap			$ 365,000,000									$ 215,900,000
ACC | Net Metering | APS
Change in regulatory asset
Cost of service, resource comparison proxy method, maximum annual percentage decrease																													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					0.094										0.094							0.105
ACC | Net Metering | APS | Subsequent Event
Change in regulatory asset
Cost of service, resource comparison proxy method, maximum annual percentage decrease	10.00%
Second-year export energy price (in dollars per kWh) | $ / kWh	0.0846
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
Change in regulatory asset
Increase in proposed budget																																			$ 14,000,000
FERC | Environmental Improvement Surcharge | APS
Change in regulatory asset
Increase (decrease) in annual wholesale transmission rates												11,400,000
Rate matters, increase (decrease) in cost recovery, excess of annual amount												$ 1,100,000
FERC | Open Access Transmission Tariff | APS
Change in regulatory asset
Increase (decrease) in annual wholesale transmission rates								$ 4,000,000						$ (6,100,000)							$ 25,800,000
Increase (decrease) in wholesale customer rates								(3,200,000)						4,800,000							21,100,000
Increase (decrease) in retail customer rates								7,200,000						(10,900,000)							4,700,000
Increase (decrease) in retail revenue requirements								$ (28,400,000)						$ (7,400,000)							$ 4,900,000
Cost Recovery Mechanisms | ACC | Power Supply Adjustor (PSA) | APS
Change in regulatory asset
Historical component of increase in PSA (in dollars per kWh) | $ / kWh			0.004									0.004					(0.002115)								(0.002897)
Cost recovery, number of agreements | agreement																																										2
Minimum | Retail Rate Case Filing with Arizona Corporation Commission | APS
Change in regulatory asset
Fixed cost recoverable per power lost (in dollars per kWh) | $ / kWh																			0.0256
Minimum | ACC | APS
Change in regulatory asset
Operating results																			$ (69,000,000)
Minimum | ACC | RES 2018 | APS
Change in regulatory asset
Authorized spending						20,000,000
Minimum | ACC | RES 2018 | APS | Solar Communities
Settlement Agreement
Required annual capital investment																												$ 10,000,000
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																			0.0268
Maximum | ACC | RES 2018 | APS
Change in regulatory asset
Authorized spending						$ 30,000,000
Maximum | ACC | RES 2018 | APS | Solar Communities
Settlement Agreement
Required annual capital investment																												$ 15,000,000