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Business Developments And Risks And Uncertainties (Narrative) (Detail) $ in Millions |  |  | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jan. 01, 2023 USD ($) | Mar. 15, 2022 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2022 USD ($) segments | Dec. 06, 2022 USD ($) | Jul. 08, 2022 USD ($)
Business Acquisition [Line Items] |  |  |  |  |  |
Number of operating segments | segments |  |  |  | 3 |  |
Gain loss on assets and liabilities reclassified as held for sale |  |  |  | $ 0 |  |
Disposal Group Discontinued Operation Loss Gain |  |  | $ 54 |  |  |
GO PSA [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Proceeds from GO PSA |  | $ 1,000 |  |  |  |
Puerto Rico Electric Power Authority [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Outstanding bonds |  |  | $ 945 | $ 945 |  |
National Public Finance Guarantee Corporation [Member] | GO PSA [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Conditional value instrument additional recoveries from the percentage of sales and usage tax receipts |  |  | 5.50% | 5.50% |  |
Acceleration and commutation payment |  |  |  | $ 277 |  |
National Public Finance Guarantee Corporation [Member] | Puerto Rico Highway and Transportation Authority [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Acceleration and commutation payment |  |  |  | 556 |  |
Cash |  |  |  |  | $ 46 | $ 33
Expected bonds issued |  |  |  |  | $ 177 | $ 358
Maximum [Member] | National Public Finance Guarantee Corporation [Member] | GO and PBA [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Outstanding bonds |  |  | $ 0 | 0 |  |
Minimum [Member] | National Public Finance Guarantee Corporation [Member] | GO and PBA [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Outstanding bonds |  |  | 495 | 495 |  |
Gross par outstanding |  |  | 380 | 380 |  |
National [Member] | Maximum [Member] | Puerto Rico Highway and Transportation Authority [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Outstanding bonds |  |  | 0 | 0 |  |
National [Member] | Minimum [Member] | Puerto Rico Highway and Transportation Authority [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Outstanding bonds |  |  | 910 | 910 |  |
Gross par outstanding |  |  | 581 | 581 |  |
Puerto Rico [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Claims payments |  |  |  | 189 |  |
Outstanding bonds |  |  | $ 1,000 | $ 1,000 |  |
Puerto Rico [Member] | Subsequent Event [Member] | National Public Finance Guarantee Corporation [Member] |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |
Claims payments | $ 18 |  |  |  |  |

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