Regulatory Matters - Narrative (Details) Customer in Thousands																				12 Months Ended
	Feb. 14, 2020 USD ($)	Feb. 01, 2020 USD ($) $ / kWh	Nov. 14, 2019 USD ($) Customer	Oct. 31, 2019 USD ($)	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 ($)	Jun. 01, 2018 USD ($)	May 01, 2018 $ / kWh	Feb. 20, 2018	Feb. 15, 2018 USD ($)	Feb. 01, 2018 $ / kWh	Jan. 08, 2018 USD ($)	Nov. 20, 2017 USD ($)	Dec. 20, 2016 $ / kWh	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 $ / kWh	Dec. 31, 2012 $ / kWh	Jul. 01, 2019 USD ($)	Mar. 15, 2019 agreement	Dec. 31, 2018 USD ($)	Jun. 29, 2018 USD ($)	Nov. 14, 2017 USD ($)	Sep. 01, 2017 USD ($)	Jun. 30, 2017 USD ($)
Regulatory Matters [Line Items]
Ballot initiative, proposed required energy supply to be obtained from renewable sources (as a percent)														50.00%
Number of customers | Customer			13
Inconvenience payment			$ 25
ARIZONA PUBLIC SERVICE COMPANY | Lost Fixed Cost Recovery Mechanism
Regulatory Matters [Line Items]
Fixed cost recoverable per residential power lost (in dollars per kWh) | $ / kWh																							0.031
Fixed costs recoverable per residential power lost (in dollars per kWh) | $ / kWh																							0.023
Fixed costs recoverable per power lost (in dollars per kWh) | $ / kWh																						0.025
Rate matter cap percentage of retail revenue																					1.00%
Amount of adjustment approved representing prorated sales losses pending approval									$ 36,200,000						$ 60,700,000
Decrease in amount of adjustment representing prorated sales losses									$ 24,500,000
ARIZONA PUBLIC SERVICE COMPANY | ACC
Regulatory Matters [Line Items]
Requested rate decrease for tax act				$ (184,000,000)							$ 86,500,000						$ 119,100,000
Requested rate increase (decrease), deferred taxes amortization, period								28 years 6 months
Requested rate increase (decrease), amount, one-time bill credit					$ 64,000,000
Requested rate increase (decrease), amount, one-time bill credit, additional benefit					$ 39,500,000
Regulatory impact, operating results																					$ (10,000,000)
ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Amount of proposed budget																								$ 86,300,000			$ 89,900,000			$ 90,000,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Demand Side Management Adjustor Charge 2018
Regulatory Matters [Line Items]
Amount of proposed budget																					51,900,000					$ 34,100,000		$ 52,600,000	$ 52,600,000
ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
Fuel And purchased power costs, excess annual limit																					$ 16,400,000
Maximum increase decrease in PSA rate (in dollars per kWh) | $ / kWh																0.004
PSA rate (in dollars per kWh) | $ / kWh										(0.001658)						(0.004555)
Forward component of PSA rate (in dollars per kWh) | $ / kWh										(0.000536)						(0.002009)
Historical component of PSA rate (in dollars per kWh) | $ / kWh										0.001122						0.002546
ARIZONA PUBLIC SERVICE COMPANY | ACC | Net Metering
Regulatory Matters [Line Items]
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
Guaranteed export price period																			10 years
Settlement agreement, energy price for exported energy (in dollars per kWh) | $ / kWh																			0.129
Request second-year energy price for exported energy | $ / kWh							0.105						0.116
ARIZONA PUBLIC SERVICE COMPANY | FERC | Transmission rates, transmission cost adjustor and other transmission matters
Regulatory Matters [Line Items]
Rate matters, increase (decrease) in cost recovery						$ (4,900,000)						$ (22,700,000)
Cost Recovery Mechanisms | ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
PSA rate in prior years (in dollars per kWh) | $ / kWh										(0.002897)
Number of agreements | agreement																									2
Solar Communities | ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Program term																		3 years
Minimum | ARIZONA PUBLIC SERVICE COMPANY | ACC
Regulatory Matters [Line Items]
Regulatory impact, operating results				$ 69,000,000
Minimum | Solar Communities | ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Required annual capital investment																		$ 10,000,000
Maximum | Solar Communities | ARIZONA PUBLIC SERVICE COMPANY | ACC | Arizona Renewable Energy Standard and Tariff 2018
Regulatory Matters [Line Items]
Required annual capital investment																		$ 15,000,000
Subsequent Event | ARIZONA PUBLIC SERVICE COMPANY | Lost Fixed Cost Recovery Mechanism
Regulatory Matters [Line Items]
Amount of adjustment approved representing prorated sales losses pending approval	$ 26,600,000
Decrease in amount of adjustment representing prorated sales losses	$ 9,600,000
Subsequent Event | ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
PSA rate (in dollars per kWh) | $ / kWh		0.000456
Forward component of PSA rate (in dollars per kWh) | $ / kWh		0.002086
Historical component of PSA rate (in dollars per kWh) | $ / kWh		0.001630
Subsequent Event | ARIZONA PUBLIC SERVICE COMPANY | FERC | Environmental Improvement Surcharge
Regulatory Matters [Line Items]
Rate matters, increase (decrease) in cost recovery		$ (8,750,000)
Subsequent Event | Cost Recovery Mechanisms | ARIZONA PUBLIC SERVICE COMPANY | ACC | Power Supply Adjustor (PSA)
Regulatory Matters [Line Items]
Maximum increase decrease in PSA rate (in dollars per kWh) | $ / kWh		0.004
PSA rate in prior years (in dollars per kWh) | $ / kWh		(0.002115)
Forecast | ARIZONA PUBLIC SERVICE COMPANY | FERC | Environmental Improvement Surcharge
Regulatory Matters [Line Items]
Rate matters, increase (decrease) in cost recovery, excess of annual amount																				$ (2,000,000.0)