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Insurance In Force (Summary Of Company's Reinsurance Agreements For U.S. Public Finance And Structured Finance And International Insurance Operations) (Detail) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
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Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers |  | $ 2,724 | $ 4,200
Reinsurance Recoverables Secured By Letters Of Credit Or Trust Amount |  | 30 |
Reinsurance Recoverable | [1] | 6 |
Assured Guaranty Corp [Member] |  |  |
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers |  | 1,031 |
Reinsurance Recoverable | [1] | 3 |
Assured Guaranty Re Ltd [Member] |  |  |
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers |  | 1,321 |
Reinsurance Recoverables Secured By Letters Of Credit Or Trust Amount |  | 27 |
Reinsurance Recoverable | [1] | 3 |
Overseas Private Investment Corporation [Member] |  |  |
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers |  | 281 |
Others [Member] |  |  |
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers |  | 91 |
Reinsurance Recoverables Secured By Letters Of Credit Or Trust Amount |  | $ 3 |
[1] | Total reinsurance recoverable is primarily related to recoverables on unpaid losses.

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- Definition Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6824-158387 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6485522&loc=d3e21409-158489 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),6) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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