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Regulatory Matters - Narrative (Details) Customer in Thousands |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12 Months Ended |  |  |  |  |  |  |
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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) |  |  |  |  |  |  |  |  |  |

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