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Insurance Regulatory Restrictions - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2012 | Dec. 31, 2011
Insurance Regulatory Restrictions [Line Items] |  |
Qualified statutory capital | $ 628,302 | $ 684,610
Average rates of return on its admitted assets | 8.01% | 7.45%
Ambac Assurance [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Segregated account reported statutory policyholder surplus | 100,000 | 495,293
Segregated Account [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Segregated account reported statutory policyholder surplus | (61,812) | 105,899
Segregated Account [Member] | Ambac Assurance [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Segregated account's insurance liabilities | 163,687 |
Restricted stock and restricted stock units RSU [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Policyholders' surplus percentage | 10.00% |
Performance units [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Discounting loss reserves and estimated impairment losses on subsidiary guarantees | 5.10% |
Performance units [Member] | Minimum [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Quarterly dividend percentage | 15.00% |
Performance units [Member] | Maximum [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Cash dividends paid on common stock | 0 | 0
Prescribed Practice Discount Rate [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Statutory surplus | 117,602 | 98,225
Prescribed practice surplus notes value [Member] |  |
Insurance Regulatory Restrictions [Line Items] |  |
Statutory surplus | $ 35,761 | $ 84,344

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- Details
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- Definition This element represents the amount of liabilities not assumed via an excess of loss reinsurance contract due to reaching the reinsurance cap of the agreement. + References No definition available. + Details
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- Definition Percentage Of Policy Holders Surplus + References No definition available. + Details
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- Definition Discount rate percentage for the purpose of discounting statutory loss reserves and estimated impairment losses on subsidiary guarantees prescribed the regulator. + References No definition available. + Details
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- Definition No quarterly dividend may exceed the dividend paid in the corresponding quarter by more than this percentage without notification to the regulator. + References No definition available. + Details
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- Definition Statutory Accounting Practices defined as policyholders' surplus plus contingency reserves. + References No definition available. + Details
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- Definition Amount of dividends distributed to shareholders in the current accounting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 50 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6483535&loc=d3e16392-158451 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 60 -Paragraph 60 -Subparagraph h(3) -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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- Definition Amount as of the balance sheet date of each item listed to reconcile the differences resulting from applying state prescribed statutory accounting practices rather than statutory accounting practices prescribed by National Association of Insurance Commissioners. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 505 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24746-158529 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 94-5 -Paragraph 8, 9 -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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- Definition The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 24 -Subparagraph c -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 60 -Paragraph 60 -Subparagraph h -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. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 94-5 -Paragraph 8, 9 -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. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.23(c)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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