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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 | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | $ 304 | $ 385 | $ 416
United States [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 238 | 310 | 299
United Kingdom [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 27 | 30 | 36
Europe Excluding United Kingdom [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 4 | 4 | 7
Internationally Diversified [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 3 | 3 | 9
Other Americas [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 26 | 29 | 49
Asia [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 2 | 3 | 4
Other [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | $ 4 | $ 6 | $ 12

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- Definition Premiums Earned Net Financial Guarantee Insurance Contracts And Insured Derivatives + References No definition available. + Details
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Balance Type: | credit
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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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