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Business Developments And Risks And Uncertainties (Narrative) (Detail) $ in Millions |  |  |  | 3 Months Ended
--- | --- | --- | --- | ---
Mar. 15, 2022 USD ($) | Jan. 31, 2022 USD ($) | Jan. 01, 2022 USD ($) | Jun. 30, 2022 USD ($) | Mar. 31, 2022 USD ($) segments
Business Acquisition [Line Items] |  |  |  |  |
Number of operating segments | segments |  |  |  |  | 3
GO PSA [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Proceeds from GO PSA | $ 1,000 |  |  |  |
Puerto Rico Electric Power Authority [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Bankruptcy claims sold |  | $ 231 |  |  |
Percentage rate of claim which reduces potential volatility and ongoing risk |  |  |  |  | 35.00%
National Public Finance Guarantee Corporation [Member] | GO PSA [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Acceleration and commutation payment |  |  |  |  | $ 277
Subsequent Event [Member] | National Public Finance Guarantee Corporation [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Bonds issued |  |  |  | $ 1,200 |
Subsequent Event [Member] | National Public Finance Guarantee Corporation [Member] | Puerto Rico Highway and Transportation Authority [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Cash |  |  |  | 264 |
Contingent value instrument |  |  |  | $ 2,200 |
Maximum [Member] | National Public Finance Guarantee Corporation [Member] | GO and PBA [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Outstanding bonds |  |  |  |  | 0
Gross par outstanding |  |  |  |  | 0
Minimum [Member] | National Public Finance Guarantee Corporation [Member] | GO and PBA [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Outstanding bonds |  |  |  |  | 495
Gross par outstanding |  |  |  |  | 380
Puerto Rico [Member] |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Claims payments |  |  | $ 47 |  |
Outstanding bonds |  |  |  |  | $ 2,100

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