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Regulatory Matters - Four Corners and Cholla (Details) - APS - USD ($) $ in Millions | 1 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Apr. 30, 2018 | Sep. 30, 2020
SCE | Four Corners Units 4 and 5 |  |  |
Business Acquisition [Line Items] |  |  |
Settlement agreement, ACC approved rate adjustment, annualized customer impact | $ 58.5 | $ 67.5 |
Retired power plant costs |  |  |
Business Acquisition [Line Items] |  |  |
Net book value |  |  | $ 61.0
Navajo Plant |  |  |
Business Acquisition [Line Items] |  |  |
Net book value |  |  | $ 74.0

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