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Background and Business Description - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Mar. 15, 2012
Background And Basis Of Presentation [Line Items] |  |  |
Current cash and investments | $ 30,357 |  |
Net par exposure for policies allocated to the segregated account | 27,162,620 |  |
Tax refunds received | 38,486 |  |
Interest on the secured note accrues | 4.50% |  |
Available secured notes including capitalized interest | 470,498 |  |
Minimum surplus amount | 100,000 |  |
Insurance liabilities allocated to segregated account | 6,245,484 |  |
Segregated Account's insurance liabilities | 163,687 |  |
Percentage of permitted policy claim | 25.00% |  |
Outstanding Segregated Account Surplus Notes | 53,000 |  |
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 debt securities by a holder | 56,930 |  |
Internal Revenue Service (IRS) [Member] |  |  |
Background And Basis Of Presentation [Line Items] |  |  |
Minimum payment to IRS | 100,000 |  |
Reduction in NOLs rate | 10.00% |  |
Ambac Assurance [Member] |  |  |
Background And Basis Of Presentation [Line Items] |  |  |
Issuance of secured note to segregated account | 2,000,000 |  |
Secured note maturity year | 2050 |  |
Interest on the secured note accrues | 4.50% |  |
Ambac [Member] |  |  |
Background And Basis Of Presentation [Line Items] |  |  |
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 |  |
5.1% junior surplus notes, segregated account, due 2020 [Member] |  |  |
Background And Basis Of Presentation [Line Items] |  |  |
Segregated Account issue of junior surplus notes | 350,000 |  |
5.1% junior surplus notes, segregated account, due 2020 [Member] | OSS Settlement Agreement [Member] |  |  |
Background And Basis Of Presentation [Line Items] |  |  |
Segregated Account issue of junior surplus notes | $ 36,082 |  |

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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 Amount of insurance liabilities allocated to the Segregated Account of Ambac Assurance from Ambac Assurance as of the balance sheet date. + 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 Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References No definition available. + Details
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