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Regulatory Matters - Four Corners, Cholla and Navajo Plant (Details) - APS - USD ($) $ in Millions |  |  | 1 Months Ended
--- | --- | --- | ---
Aug. 02, 2021 | Jun. 30, 2021 | Sep. 30, 2018 | Apr. 30, 2018
Subsequent Event | Navajo Nation, Economic Development Organization | Coal Community Transition Plan | Retail Rate Case Filing with Arizona Corporation Commission | ACC |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Disallowance of annual amortization percentage | 15.00% |  |  |
SCE | Four Corners Units 4 and 5 |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Settlement agreement, ACC approved rate adjustment, annualized customer impact |  |  | $ 58.5 | $ 67.5
Estimated write-off of cost deferrals |  | $ 75.0 |  |
SCR plant investments |  | 320.0 |  |
SCE | Four Corners Units 4 and 5 | Subsequent Event |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Disallowance of plant investments | $ 399.0 |  |  |
Cost deferrals | $ 61.0 |  |  |
Retired power plant costs |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Net book value |  | 48.9 |  |
Navajo Plant |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Net book value |  | 67.0 |  |
Navajo Plant, Coal Reclamation Regulatory Asset |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Net book value |  | $ 17.5 |  |

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