| **Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - ARIZONA PUBLIC SERVICE COMPANY - USD ($) $ in Thousands** |          | 12 Months Ended |
|---------------------------------------------------------------------------------------------------------------------------------------------------|----------|-----------------|
||
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | $ 1,255,870     | $ 1,087,235 |   |
| Total Unrealized Gains                                                                                                                            |     | 363,476         | 230,781 |   |
| Total Unrealized Losses                                                                                                                           |     | (669)           | (7,237) |   |
| Amortized cost                                                                                                                                    |     | 691,000         | 635,000 |   |
| **Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds**                                 |     |            |   |   |
| Realized gains                                                                                                                                    |     | 11,132          | 6,680 | $ 21,830 |
| Realized losses                                                                                                                                   |     | (6,972)         | (13,552) | (13,155) |
| Proceeds from the sale of securities                                                                                                              |     | 719,034         | 653,033 | 546,339 |
| **Fair value of fixed income securities, summarized by contractual maturities**                                                                   |     |            |   |   |
| Employee medical claims amount                                                                                                                    | $ 15,000 |            |   |   |
| Equity securities                                                                                                                                 |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Equity Securities                                                                                                                                 |     | 536,858         | 447,138 |   |
| Total Unrealized Gains                                                                                                                            |     | 337,681         | 222,147 |   |
| Total Unrealized Losses                                                                                                                           |     | 0               | (459) |   |
| Fixed income securities                                                                                                                           |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 716,137         | 637,356 |   |
| Total Unrealized Gains                                                                                                                            |     | 25,795          | 8,634 |   |
| Total Unrealized Losses                                                                                                                           |     | (669)           | (6,778) |   |
| **Fair value of fixed income securities, summarized by contractual maturities**                                                                   |     |            |   |   |
| Less than one year                                                                                                                                |     | 99,386          |   |   |
| 1 year - 5 years                                                                                                                                  |     | 299,410         |   |   |
| 5 years - 10 years                                                                                                                                |     | 105,797         |   |   |
| Greater than 10 years                                                                                                                             |     | 211,544         |   |   |
| Total                                                                                                                                             |     | 716,137         |   |   |
| Other Receivables from Broker-Dealers and Clearing                                                                                                |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 2,875           | 2,741 |   |
| Total Unrealized Gains                                                                                                                            |     | 0               | 0 |   |
| Total Unrealized Losses                                                                                                                           |     | 0               | 0 |   |
| Nuclear Decommissioning Trusts                                                                                                                    |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 1,010,775       | 851,134 |   |
| **Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds**                                 |     |            |   |   |
| Realized gains                                                                                                                                    |     | 11,024          | 6,679 | 21,813 |
| Realized losses                                                                                                                                   |     | (6,972)         | (13,552) | (13,146) |
| Proceeds from the sale of securities                                                                                                              |     | 473,806         | 554,385 | 542,246 |
| Nuclear Decommissioning Trusts | Equity securities                                                                                                |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Equity Securities                                                                                                                                 |     | 529,716         | 402,008 |   |
| Nuclear Decommissioning Trusts | Fixed income securities                                                                                          |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 478,658         | 446,978 |   |
| **Fair value of fixed income securities, summarized by contractual maturities**                                                                   |     |            |   |   |
| Less than one year                                                                                                                                |     | 26,984          |   |   |
| 1 year - 5 years                                                                                                                                  |     | 136,139         |   |   |
| 5 years - 10 years                                                                                                                                |     | 105,797         |   |   |
| Greater than 10 years                                                                                                                             |     | 209,738         |   |   |
| Total                                                                                                                                             |     | 478,658         |   |   |
| Nuclear Decommissioning Trusts | Other Receivables from Broker-Dealers and Clearing                                                               |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 2,401           | 2,148 |   |
| Coal Reclamation Escrow Account | Fixed income securities                                                                                         |     |            |   |   |
| **Fair value of fixed income securities, summarized by contractual maturities**                                                                   |     |            |   |   |
| Less than one year                                                                                                                                |     | 31,953          |   |   |
| 1 year - 5 years                                                                                                                                  |     | 25,229          |   |   |
| 5 years - 10 years                                                                                                                                |     | 0               |   |   |
| Greater than 10 years                                                                                                                             |     | 1,806           |   |   |
| Total                                                                                                                                             |     | 58,988          |   |   |
| Active Union Medical Trust | Fixed income securities                                                                                              |     |            |   |   |
| **Fair value of fixed income securities, summarized by contractual maturities**                                                                   |     |            |   |   |
| Less than one year                                                                                                                                |     | 40,449          |   |   |
| 1 year - 5 years                                                                                                                                  |     | 138,042         |   |   |
| 5 years - 10 years                                                                                                                                |     | 0               |   |   |
| Greater than 10 years                                                                                                                             |     | 0               |   |   |
| Total                                                                                                                                             |     | 178,491         |   |   |
| Other Special Use Funds                                                                                                                           |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 245,095         | 236,101 |   |
| **Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds**                                 |     |            |   |   |
| Realized gains                                                                                                                                    |     | 108             | 1 | 17 |
| Realized losses                                                                                                                                   |     | 0               | 0 | (9) |
| Proceeds from the sale of securities                                                                                                              |     | 245,228         | 98,648 | $ 4,093 |
| Other Special Use Funds | Equity securities                                                                                                       |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Equity Securities                                                                                                                                 |     | 7,142           | 45,130 |   |
| Other Special Use Funds | Fixed income securities                                                                                                 |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | 237,479         | 190,378 |   |
| Other Special Use Funds | Other Receivables from Broker-Dealers and Clearing                                                                      |     |            |   |   |
| **Nuclear decommissioning trust fund assets**                                                                                                     |     |            |   |   |
| Fair Value                                                                                                                                        |     | $ 474           | $ 593 |   |

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