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Special Purpose Entities, Including Variable Interest Entities - Summary of Carrying Amount of Assets, Liabilities and Maximum Exposure to Loss of Ambac's Variable Interests in Non-Consolidated Variable Interest Entities (Detail) (Variable interest entity [Member], USD $) In Thousands, unless otherwise specified | Dec. 31, 2012 | Dec. 31, 2011
--- | --- | ---
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | $ 93,517,995 | $ 111,748,270
Insurance Assets | 1,840,265 | 2,196,161
Insurance Liabilities | 7,463,635 | 9,207,107
Derivative Liabilities | 201,434 | 183,666
Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 56,421,767 | 73,854,544
Insurance Assets | 1,298,086 | 1,627,129
Insurance Liabilities | 6,830,277 | 8,506,417
Derivative Liabilities | 172,771 | 168,816
Global Public Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 37,096,228 | 37,893,726
Insurance Assets | 542,179 | 569,032
Insurance Liabilities | 633,358 | 700,690
Derivative Liabilities | 28,663 | 14,850
Collateralized debt obligations [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 10,176,522 | 14,093,243
Insurance Assets | 9,673 | 15,096
Insurance Liabilities | 13,328 | 105,219
Derivative Liabilities | 113,057 | 120,614
Residential mortgage-backed securities [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 24,008,616 | 30,307,753
Insurance Assets | 603,867 | 783,329
Insurance Liabilities | 3,969,336 | 5,396,711
Derivative Liabilities |  |
Mortgage-backed-commercial [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 643,387 | 685,870
Insurance Assets |  |
Insurance Liabilities |  |
Derivative Liabilities | 2,418 | 6,241
Other consumer asset-backed [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 5,895,377 | 7,851,980
Insurance Assets | 101,494 | 129,234
Insurance Liabilities | 1,042,522 | 1,315,146
Derivative Liabilities | 45,610 | 35,583
Other commercial asset-backed [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 10,192,858 | 13,363,434
Insurance Assets | 451,048 | 559,884
Insurance Liabilities | 1,215,074 | 1,045,477
Derivative Liabilities | 7,293 | 4,541
Other [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 5,505,007 | 7,552,264
Insurance Assets | 132,004 | 139,586
Insurance Liabilities | 590,017 | 643,864
Derivative Liabilities | $ 4,393 | $ 1,837

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- Definition The net carrying amount of derivative assets or liabilities in the reporting entity's statement of financial position that relate to the entity's variable interests in Variable Interest Entities (VIEs) where the VIEs are not consolidated. + References No definition available. + Details
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- Definition The carrying amount of insurance assets in the reporting entity's statement of financial position that relate to the entity's variable interests in Variable Interest Entities (VIEs) where the VIEs are not consolidated. + References No definition available. + Details
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- Definition The carrying amount of insurance liabilities in the reporting entity's statement of financial position that relate to the entity's variable interests in Variable Interest Entities (VIEs) where the VIEs are not consolidated. + References No definition available. + Details
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- Definition The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph b -URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5728-111685 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5747-111685 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS140-4/FIN46(R) -Paragraph C6 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Details
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