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Business Segments (Summary Of Premiums Earned On Financial Guarantees And Insured Derivatives By Geographic Location Of Risk) (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | $ 43 | $ 75 | $ 93 | $ 151
United States [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 35 | 58 | 76 | 117
United Kingdom [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 1 | 7 | 1 | 14
Europe Excluding United Kingdom [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 0 | 2 | 1 | 3
Internationally Diversified [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 1 | 0 | 1 | 0
Other Americas [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 5 | 7 | 12 | 14
Asia [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 0 | 0 | 0 | 1
Other [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | $ 1 | $ 1 | $ 2 | $ 2

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- Definition Premiums Earned Net Financial Guarantee Insurance Contracts And Insured Derivatives + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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- Details
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- Details
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- Details
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- Details
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- Details
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Balance Type: |
Period Type: |

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- Details
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