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Business Developments And Risks And Uncertainties (Narrative) (Detail) $ / shares in Units, $ in Millions |  | 12 Months Ended
--- | --- | ---
Jan. 01, 2025 USD ($) | Dec. 31, 2024 USD ($) Segments | Dec. 31, 2023 USD ($) $ / shares | Dec. 31, 2022 USD ($)
Business Acquisition [Line Items] |  |  |  |
Number of operating segments | Segments |  | 3 |  |
Dividends paid |  | $ 0 | $ 409 | $ 0
Dividend declared per common share | $ / shares |  |  | $ 8 |
O 2023 Q4 Dividends [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Dividend payment date |  | Dec. 22, 2023 |  |
Puerto Rico Electric Power Authority [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Claims payments |  | $ 137 |  |
Outstanding bonds |  | 670 |  |
Subsequent Event | Puerto Rico Electric Power Authority [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Claims payments | $ 13 |  |  |
National [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Dividends from subsidiaries |  | 69 |  | $ 72
National [Member] | S 2023 A Dividends [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Dividends from subsidiaries |  |  | $ 550 |
National [Member] | O 2024 A Right Dividends [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Dividends from subsidiaries |  | $ 69 |  |
National [Member] | O 2023 A Right Dividends [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Dividends from subsidiaries |  |  | $ 97 |

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