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Regulatory Matters - Capital Structure and Costs of Capital (Details) - APS - $ / kWh | Oct. 01, 2021 | May 01, 2020 | Oct. 31, 2019 | May 01, 2019
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Cost of Capital |  |  |  |
Long-term debt |  |  | 4.10% |
Common stock equity |  |  | 10.15% |
Weighted-average cost of capital |  |  | 7.41% |
Retail Rate Case Filing with Arizona Corporation Commission |  |  |  |
Capital Structure |  |  |  |
Common stock equity |  |  | 54.70% |
Retail Rate Case Filing with Arizona Corporation Commission | ACC |  |  |  |
Capital Structure |  |  |  |
Long-term debt |  |  | 45.30% |
Net Metering | ACC |  |  |  |
Cost of Capital |  |  |  |
Second-year export energy price (in dollars per kWh) |  | 0.094 |  | 0.105
Net Metering | ACC | Forecast |  |  |  |
Cost of Capital |  |  |  |
Second-year export energy price (in dollars per kWh) | 0.105 |  |  |

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