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Schedule II - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Mar. 15, 2012
Amount shall have been paid or paid into escrow by the company |  |  | $ 30,000
Reduction in NOLs rate | (1.10%) | 0.20% |
Beneficial ownership of company common stock held by external investor shares | 13,500,000 |  |
Percentage of stock value of reorganized company | 4.50% |  |
Ownership of senior debts | 56,930 |  |
Discontinued Liabilities subject to compromise | 211,896 |  |
Liabilities subject to compromise contractual interest on debt | 85,371 | 110,093 |
5.1% junior surplus notes, segregated account, due 2020 [Member] |  |  |
Segregated Account issue of junior surplus notes | 350,000 |  |
Internal Revenue Service (IRS) [Member] |  |  |
Minimum payment to IRS | 100,000 |  |
Reduction in NOLs rate | 10.00% |  |
AMBAC FINANCIAL GROUP, INC PARENT COMPANY ONLY [Member] |  |  |
Amount shall have been paid or paid into escrow by the company | 30,000 |  |
Shareholders ownership interest | 5.00% |  |
Increase in ownership percentage, by value | 50.00% |  |
Increase in ownership percentage, rolling period beginning with the last Ownership Change | Three-year |  |
Beneficial ownership of company common stock held by external investor shares | 13,500,000 |  |
Percentage of stock value of reorganized company | 4.50% |  |
Ownership of senior debts | 56,930 |  |
Discontinued Liabilities subject to compromise | 211,896 | 126,524 |
Liabilities subject to compromise contractual interest on debt | 85,372 | 110,093 |
AMBAC FINANCIAL GROUP, INC PARENT COMPANY ONLY [Member] | 5.1% junior surplus notes, segregated account, due 2020 [Member] |  |  |
Segregated Account issue of junior surplus notes | 350,000 |  |
AMBAC FINANCIAL GROUP, INC PARENT COMPANY ONLY [Member] | Internal Revenue Service (IRS) [Member] |  |  |
Minimum payment to IRS | 100,000 |  |
Reduction in NOLs rate | 10.00% |  |
First five years [Member] | AMBAC FINANCIAL GROUP, INC PARENT COMPANY ONLY [Member] |  |  |
Reimbursement amount | 5,000 |  |
All later years [Member] | AMBAC FINANCIAL GROUP, INC PARENT COMPANY ONLY [Member] |  |  |
Reimbursement amount | $ 4,000 |  |

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- Definition Maximum allowable taxes payable to the IRS by certain Ambac subsidiaries with regards to settlement of adversary proceedings against the IRS as required by the Mediation Agreement. + References No definition available. + Details
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- Definition Junior Surplus Notes expected to be issued by the Segregated Account of Ambac Assurance to Ambac Financial Group upon Ambac Financial Group's emergence from bankruptcy. These Junior Surplus notes will be includable in surplus for statutory accounting purposes as prescribed or permitted by state laws and regulations. + References No definition available. + Details
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- Definition Maximum amount of senior debt securities or any combination of debt securities and other claims that would result in such holder receiving stock in reorganized Ambac pursuant to the terms of the Reorganization Plan with a value equal to or greater than 4.5% of the value of the stock of reorganized Ambac. + References No definition available. + Details
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