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Commitments and Contingencies - Superfund-Related Matters, Southwest Power Outage, Clean Air Act and Four Corners (Details) - APS $ in Millions |  |  |  |  |  | 6 Months Ended
--- | --- | --- | --- | --- | --- | ---
Aug. 02, 2021 USD ($) | Jun. 30, 2021 USD ($) | Apr. 05, 2018 plaintiff Defendant | Dec. 16, 2016 plaintiff | Aug. 06, 2013 Defendant | Jun. 30, 2021 USD ($)
SCE | Four Corners Units 4 and 5 |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |
Estimated write-off of cost deferrals |  | $ 75 |  |  |  |
SCR plant investments |  | $ 320 |  |  |  | $ 320
SCE | Four Corners Units 4 and 5 | Subsequent Event |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |
Disallowance of plant investments | $ 399 |  |  |  |  |
Cost deferrals | $ 61 |  |  |  |  |
Contaminated groundwater wells |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |
Costs related to investigation and study under Superfund site |  |  |  |  |  | $ 3
Number of defendants against whom Roosevelt Irrigation District (RID) filed lawsuit | Defendant |  |  | 28 |  | 24 |
Number of plaintiffs | plaintiff |  |  |  | 2 |  |
Settled Litigation | Contaminated groundwater wells |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |
Number of plaintiffs | plaintiff |  |  | 2 |  |  |

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- Definition Costs related to site-wide groundwater remedial investigation and feasibility study work plan because subsidiary has been found to be potentially responsible parties ("PRPs") with liability for cleanup of hazardous substances that contaminates the soil, water or air, under the Comprehensive Environmental Response, Compensation and Liability Act ("Superfund"). + References No definition available. + Details
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