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Commitments and Contingencies (Details) $ in Millions |  |  | 6 Months Ended | 172 Months Ended |
--- | --- | --- | --- | --- | ---
Jan. 01, 2024 USD ($) trust | Jan. 17, 2023 USD ($) | Jun. 30, 2026 USD ($) trust | Oct. 31, 2025 claim | Jul. 11, 2025 operator
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Production tax credit guarantees |  |  | $ 24.6 |  |
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Settlement amount, awarded to company |  |  | $ 189.7 |  |
APS |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Maximum insurance against public liability per occurrence for a nuclear incident | $ 16,300.0 |  |  |  |
Maximum available nuclear liability insurance | 500.0 |  |  |  |
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program | 15,800.0 |  |  |  |
Maximum assessment per reactor for each nuclear incident | 165.9 |  |  |  |
Annual limit per incident with respect to maximum assessment | $ 24.7 |  |  |  |
Number of VIE lessor trusts | trust | 3 |  | 3 |  |
Maximum potential retrospective assessment per incident of APS | $ 144.9 |  |  |  |
Annual payment limitation with respect to maximum potential retrospective assessment | $ 21.6 |  |  |  |
Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde |  |  | $ 2,800.0 |  |
Request second-year energy price for exported energy |  |  | 24.9 |  |
Collateral assurance based on rating triggers |  |  | $ 68.9 |  |
Period to provide collateral assurance based on rating triggers |  |  | 20 days |  |
Number of power plant operators | operator |  |  |  |  | 25
Increase (decrease) in unrecorded unconditional purchase obligation |  |  | $ 2,900.0 |  |
APS | Surety Bonds Expiring in 2028 |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Surety bonds expiring, amount |  |  | 26.1 |  |
APS | Letter of Credit |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Outstanding letters of credit |  |  | 30.4 |  |
APS | Contaminated Groundwater Wells |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Costs related to investigation and study under Superfund site |  |  | 3.0 |  |
Remedial investigation work |  | $ 1.7 |  |  |
APS | Contaminated Groundwater Wells | Pending Litigation |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Settlement amount |  |  | 8.3 |  |
APS | Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Number of claims submitted | claim |  |  |  | 12 |
Settlement amount, awarded to company |  |  | $ 55.2 |  |
NTEC | Four Corners |  |  |  |  |
Schedule of Commitments and Contingencies [Line Items] |  |  |  |  |
Asset purchase agreement, option to purchase, ownership interest, percentage |  |  | 7.00% |  |

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