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Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Millions | 1 Months Ended | 12 Months Ended | 36 Months Ended
--- | --- | --- | ---
May 31, 2014 $ / kWh | Dec. 31, 2022 USD ($) $ / shares shares | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2022 USD ($) $ / shares shares
Approximate remaining average useful lives of utility property |  |  |  |  |
Depreciation |  | $ 632 | $ 575 | $ 553 |
Depreciation rates (as a percent) |  | 3.03% | 2.87% | 2.84% |
Allowance for Funds Used During Construction |  |  |  |  |
Composite rate used to calculate AFUDC (as a percent) |  | 5.75% | 6.75% | 6.72% |
Income Taxes |  |  |  |  |
Percent likelihood largest tax benefit amount is realized (greater than) |  | 50.00% |  |  |
Intangible Assets |  |  |  |  |
Amortization expense |  | $ 84 | $ 80 | $ 70 |
Estimated amortization expense on existing intangible assets over the next five years |  |  |  |  |
Estimated amortization expense, next year |  | 81 |  |  | $ 81
Estimated amortization expense, in two years |  | 60 |  |  | 60
Estimated amortization expense, in three years |  | 48 |  |  | 48
Estimated amortization expense, in four years |  | 33 |  |  | 33
Estimated amortization expense, in five years |  | $ 14 |  |  | $ 14
Remaining amortization period for intangible assets |  | 6 years |  |  |
Pinnacle West |  |  |  |  |
Preferred Stock |  |  |  |  |
Preferred stock, shares authorized (in shares) | shares |  | 10,000,000 |  |  | 10,000,000
Preferred stock, shares outstanding (in shares) | shares |  | 0 |  |  | 0
Arizona Public Service Company |  |  |  |  |
Nuclear Fuel |  |  |  |  |
Charges for the permanent disposal of spent nuclear fuel (in dollars per kWh) | $ / kWh | 0.001 |  |  |  |
Preferred Stock |  |  |  |  |
Preferred stock, shares authorized (in shares) | shares |  | 15,535,000 |  |  | 15,535,000
Preferred stock, shares outstanding (in shares) | shares |  | 0 |  |  | 0
Preferred stock par or stated value per share 1 (in dollars per share) | $ / shares |  | $ 25 |  |  | $ 25
Preferred stock par or stated value per share 2 (in dollars per share) | $ / shares |  | 50 |  |  | 50
Preferred stock par or stated value per share 3 (in dollars per share) | $ / shares |  | $ 100 |  |  | $ 100
Minimum |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Depreciation rates (as a percent) |  |  |  |  | 1.37%
Maximum |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Depreciation rates (as a percent) |  |  |  |  | 12.15%
Investments |  |  |  |  |
Ownership percentage for classification as cost method investments by El Dorado |  | 20.00% |  |  |
Steam Generation |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 12 years |  |  |
Nuclear Plant |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 25 years |  |  |
Other Generation |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 18 years |  |  |
Transmission |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 38 years |  |  |
Distribution |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 33 years |  |  |
General Plant |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 6 years |  |  |
El Paso's Interest in Four Corners | 4CA |  |  |  |  |
Utility Plant and Depreciation [Line Items] |  |  |  |  |
Ownership interest acquired (as a percent) |  | 7.00% |  |  | 7.00%

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