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v3.23.1

Commitments and Contingencies (Details) $ in Millions |  |  |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended | 120 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2022 USD ($) | Nov. 02, 2021 USD ($) | Nov. 01, 2021 USD ($) | Jul. 03, 2018 USD ($) | Apr. 05, 2018 plaintiff defendant | Dec. 16, 2016 plaintiff | Jul. 06, 2016 | Aug. 06, 2013 defendant | Mar. 31, 2023 USD ($) Trust MW | Dec. 31, 2022 USD ($) | Jun. 30, 2021 USD ($) claim | Apr. 18, 2023 USD ($)
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Increase in contractual obligations |  |  |  |  |  |  |  |  | $ 1,900.0 |  |  |
Production tax credit guarantees |  |  |  |  |  |  |  |  | 33.0 |  |  |
Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Non recourse construction financing agreement |  |  |  |  |  |  |  |  |  |  |  | $ 140.0
Financing agreement of sponsor equity |  |  |  |  |  |  |  |  |  |  |  | $ 40.0
Purchase Power Lease Contracts |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Increase in contractual obligations |  |  |  |  |  |  |  |  | $ 1,600.0 |  |  |
Kūpono Solar |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Project plant capacity (in MW's) | MW |  |  |  |  |  |  |  |  | 42 |  |  |
Asset purchase agreement |  |  |  |  |  |  |  |  | 20 years |  |  |
APS |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Maximum insurance against public liability per occurrence for a nuclear incident (up to) |  |  |  |  |  |  |  |  | $ 13,700.0 |  |  |
Maximum available nuclear liability insurance (up to) |  |  |  |  |  |  |  |  | 450.0 |  |  |
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program |  |  |  |  |  |  |  |  | 13,200.0 |  |  |
Maximum retrospective premium assessment per reactor for each nuclear liability incident |  |  |  |  |  |  |  |  | 137.6 |  |  |
Annual limit per incident with respect to maximum retrospective premium assessment |  |  |  |  |  |  |  |  | $ 20.5 |  |  |
Number of VIE lessor trusts | Trust |  |  |  |  |  |  |  |  | 3 |  |  |
Maximum potential retrospective assessment per incident of APS |  |  |  |  |  |  |  |  | $ 120.1 |  |  |
Annual payment limitation with respect to maximum potential retrospective premium assessment |  |  |  |  |  |  |  |  | 17.9 |  |  |
Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde |  |  |  |  |  |  |  |  | 2,800.0 |  |  |
Maximum amount that could be incurred under retrospective assessment of NEIL policies |  |  |  |  |  |  |  |  | 22.4 |  |  |
Collateral assurance provided based on rating triggers |  |  |  |  |  |  |  |  | $ 62.6 |  |  |
Period to provide collateral assurance based on rating triggers |  |  |  |  |  |  |  |  | 20 days |  |  |
APS | Contaminated groundwater wells |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Costs related to investigation and study under Superfund site |  |  |  |  |  |  |  |  | $ 3.0 |  |  |
Number of defendants against whom Roosevelt Irrigation District (RID) filed lawsuit | defendant |  |  |  |  | 28 |  |  | 24 |  |  |  |
Number of plaintiffs | plaintiff |  |  |  |  |  | 2 |  |  |  |  |  |
Costs claimed |  |  |  |  |  |  |  |  |  | $ 21.0 |  |
APS | Contaminated groundwater wells | Settled Litigation |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Number of plaintiffs | plaintiff |  |  |  |  | 2 |  |  |  |  |  |  |
APS | Contaminated groundwater wells | Pending Litigation |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Settlement amount | $ 20.7 |  |  |  |  |  |  |  |  |  |  |
APS | Letter of Credit |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Outstanding letters of credit |  |  |  |  |  |  |  |  | 10.0 |  |  |
APS | Surety Bonds Expiring in 2025 |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Surety bonds expiring, amount |  |  |  |  |  |  |  |  | 21.0 |  |  |
APS | Coal Combustion Waste | Four Corners |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 30.0 |  |  |
APS | Coal Combustion Waste | Four Corners | Minimum |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 10.0 |  |  |
APS | Coal Combustion Waste | Four Corners | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 15.0 |  |  |
APS | Coal Combustion Waste | Cholla |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 16.0 |  |  |
APS | Coal Combustion Waste | Cholla | Minimum |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 30.0 |  |  |
APS | Coal Combustion Waste | Cholla | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 35.0 |  |  |
APS | Coal Combustion Waste | Navajo Plant |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  |  |  |  |  |  |  | 1.0 |  |  |
APS | SCE | Four Corners Units 4 and 5 |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Disallowance of plant investments |  | $ 194.0 |  |  |  |  |  |  |  |  |  |
Cost deferrals |  | $ 215.5 |  |  |  |  |  |  |  |  |  |
Amount not recoverable |  |  |  |  |  |  |  |  | $ 154.4 |  |  |
4C Acquisition, LLC | Four Corners |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Percentage of share of cost of control |  |  |  |  |  |  | 7.00% |  |  |  |  |
BCE | Clear Creek Wind Farm |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments | $ 17.1 |  |  |  |  |  |  |  |  | 0.0 |  |
Impairment of equity method investments |  |  |  |  |  |  |  |  |  | $ 12.8 |  |
NTEC | Four Corners |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Option to purchase ownership interest (as a percent) |  |  |  | 7.00% |  |  | 7.00% |  |  |  |  |
Proceeds from operating and maintenance cost reimbursement |  |  |  | $ 70.0 |  |  |  |  |  |  |  |
Asset purchase agreement, option to purchase, ownership interest, percentage |  |  |  | 7.00% |  |  |  |  |  |  |  |
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Amount awarded from other party |  |  | $ 14.3 |  |  |  |  |  |  |  | $ 123.9 |
Breach of Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste | APS |  |  |  |  |  |  |  |  |  |  |  |
Commitments and Contingencies |  |  |  |  |  |  |  |  |  |  |  |
Number of claims submitted | claim |  |  |  |  |  |  |  |  |  |  | 8 |
Amount awarded from other party |  |  | $ 4.2 |  |  |  |  |  |  |  | $ 36.0 |

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