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Financial Guarantees in Force - Summary of International Finance Guaranteed Portfolio (Detail) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017
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Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | $ 46,927,000 | $ 62,716,000
International Finance [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 13,538,000 | 16,812,000
International Finance [Member] | United Kingdom [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 10,965,000 | 13,554,000
International Finance [Member] | Australia [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 384,000 | 608,000
International Finance [Member] | Italy [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 811,000 | 877,000
International Finance [Member] | Austria [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 712,000 | 770,000
International Finance [Member] | FRANCE |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 312,000 | 329,000
International Finance [Member] | Internationally Diversified [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 213,000 | 368,000
International Finance [Member] | Other International [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | $ 141,000 | $ 306,000

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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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- Definition Amount of participating insurance in force. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 50 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6483535&loc=d3e16392-158451 + Details
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