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Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Cash equivalents | $ 23 | $ 10 |
Nuclear decommissioning trusts (Notes 12 and 18) | 1,282,845 | 1,201,246 |
Variable Interest Entity | Pinnacle West Captive Insurance Cell |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Special use fund | 34,000 | 5,000 |
Equity securities |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Nuclear decommissioning trusts (Notes 12 and 18) | 15,736 | 10,297 |
Arizona Public Service Company |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 1,691,202 | 1,564,027 |
Total Unrealized Gains | 366,844 | 358,112 |
Total Unrealized Losses | (32,136) | (40,868) |
Amortized cost | 1,224,000 | 1,120,000 |
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |
Realized gains | 76,062 | 112,094 | $ 9,437
Realized losses | (21,966) | (41,780) | (40,239)
Proceeds from the sale of securities | 1,686,094 | 1,679,722 | 1,207,197
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Nuclear decommissioning trusts (Notes 12 and 18) | 1,282,845 | 1,201,246 |
Arizona Public Service Company | Nuclear Decommissioning Trusts |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 1,282,845 | 1,201,246 |
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |
Realized gains | 75,690 | 111,922 | 9,017
Realized losses | (21,966) | (41,212) | (40,239)
Proceeds from the sale of securities | 1,330,940 | 1,324,978 | 979,639
Arizona Public Service Company | Other Special Use Funds |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 408,357 | 362,781 |
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |
Realized gains | 372 | 172 | 420
Realized losses | 0 | (568) | 0
Proceeds from the sale of securities | 355,154 | 354,744 | $ 227,558
Arizona Public Service Company | Equity securities |  |  |
Nuclear decommissioning trust fund assets |  |  |
Equity securities | 460,432 | 461,671 |
Total Unrealized Gains | 359,127 | 336,555 |
Total Unrealized Losses | (176) | 0 |
Arizona Public Service Company | Equity securities | Nuclear Decommissioning Trusts |  |  |
Nuclear decommissioning trust fund assets |  |  |
Equity securities | 435,470 | 420,680 |
Arizona Public Service Company | Equity securities | Other Special Use Funds |  |  |
Nuclear decommissioning trust fund assets |  |  |
Equity securities | 24,962 | 40,991 |
Arizona Public Service Company | Available for sale-fixed income securities |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 1,199,584 | 1,100,927 |
Total Unrealized Gains | 7,717 | 21,518 |
Total Unrealized Losses | (31,960) | (40,868) |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Less than one year | 146,382 |  |
1 year – 5 years | 482,340 |  |
5 years – 10 years | 214,128 |  |
Greater than 10 years | 356,734 |  |
Total | 1,199,584 |  |
Arizona Public Service Company | Available for sale-fixed income securities | Nuclear Decommissioning Trusts |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 844,040 | 781,333 |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Less than one year | 19,868 |  |
1 year – 5 years | 268,974 |  |
5 years – 10 years | 198,464 |  |
Greater than 10 years | 356,734 |  |
Total | 844,040 |  |
Arizona Public Service Company | Available for sale-fixed income securities | Other Special Use Funds |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 355,544 | 319,594 |
Arizona Public Service Company | Available for sale-fixed income securities | Coal Reclamation Escrow Account |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Less than one year | 87,424 |  |
1 year – 5 years | 58,598 |  |
5 years – 10 years | 0 |  |
Greater than 10 years | 0 |  |
Total | 146,022 |  |
Arizona Public Service Company | Available for sale-fixed income securities | Active Union Employee Medical Account |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Less than one year | 39,090 |  |
1 year – 5 years | 154,768 |  |
5 years – 10 years | 15,664 |  |
Greater than 10 years | 0 |  |
Total | 209,522 |  |
Arizona Public Service Company | Other |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 31,186 | 1,429 |
Total Unrealized Gains | 0 | 39 |
Total Unrealized Losses | 0 | 0 |
Arizona Public Service Company | Other | Nuclear Decommissioning Trusts |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 3,335 | (767) |
Arizona Public Service Company | Other | Other Special Use Funds |  |  |
Nuclear decommissioning trust fund assets |  |  |
Fair Value | 27,851 | $ 2,196 |
Pinnacle West | Variable Interest Entity | Pinnacle West Captive Insurance Cell |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |
Special use fund | $ 34,000 |  |

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