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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, 2023 USD ($) $ / shares shares | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2023 USD ($) $ / shares shares
Approximate remaining average useful lives of utility property |  |  |  |  |
Depreciation |  | $ 669 | $ 632 | $ 575 |
Depreciation rates (as a percent) |  | 2.98% | 3.03% | 2.87% |
Allowance for Funds Used During Construction |  |  |  |  |
Composite rate used to calculate AFUDC (as a percent) |  | 6.29% | 5.75% | 6.75% |
Income Taxes |  |  |  |  |
Percent likelihood largest tax benefit amount is realized (greater than) |  | 50.00% |  |  |
Intangible Assets |  |  |  |  |
Amortization expense |  | $ 90 | $ 84 | $ 80 |
Estimated amortization expense on existing intangible assets over the next five years |  |  |  |  |
Estimated amortization expense, next year |  | 90 |  |  | $ 90
Estimated amortization expense, in two years |  | 75 |  |  | 75
Estimated amortization expense, in three years |  | 49 |  |  | 49
Estimated amortization expense, in four years |  | 23 |  |  | 23
Estimated amortization expense, in five years |  | $ 11 |  |  | $ 11
Remaining amortization period for intangible assets |  | 5 years |  |  | 5 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 |  | 11 years |  |  | 11 years
Nuclear Plant |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 25 years |  |  | 25 years
Other Generation |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 18 years |  |  | 18 years
Transmission |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 38 years |  |  | 38 years
Distribution |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 33 years |  |  | 33 years
General Plant |  |  |  |  |
Approximate remaining average useful lives of utility property |  |  |  |  |
Average useful life |  | 7 years |  |  | 7 years

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