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Long-Term Debt (Details) - USD ($) $ in Thousands | 3 Months Ended | 4 Months Ended | 8 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Apr. 30, 2013 | Dec. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | May. 01, 2013
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Secured Debt | $ 130,571 |  |  |  |  |  |  |  |  |  | $ 130,571 |  |  |
Junior surplus note of Ambac Assurance Segregated Account |  |  |  |  |  |  |  |  | $ 350,000 |  |  |  |  | $ 350,000
Secured Debt [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount | $ 132,467 |  |  |  |  |  |  |  |  |  | $ 132,467 |  |  |
5.1% Surplus Notes, General Account, Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 10.50% |  |  |  |  |  |  |  |  |  | 10.50% |  |  |
Debt Instrument, Repurchased Face Amount | $ 11,804 |  |  |  |  |  |  |  |  |  | $ 11,804 |  |  |
Net realized gains (losses) on extinguishment of debt |  |  |  |  |  |  |  |  |  |  | 1,246 | $ 71,590 |  |
Debt Instrument, Face Amount | $ 881,496 |  |  |  | $ 893,300 |  |  |  |  |  | $ 881,496 | 893,300 |  |
5.1% Surplus Notes, Segregated Account, Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 10.50% |  |  |  |  |  |  |  |  |  | 10.50% |  |  |
Net realized gains (losses) on extinguishment of debt |  |  |  |  |  |  |  |  |  |  |  | 3,134 |  |
Debt Instrument, Face Amount | $ 39,102 |  |  |  | 39,102 |  |  |  |  |  | $ 39,102 | 39,102 |  |
5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 19.50% |  |  |  |  |  |  |  |  |  | 19.50% |  |  |
Debt Instrument, Face Amount | $ 378,039 |  |  |  | 378,039 |  |  |  |  |  | $ 378,039 | 378,039 |  |
One State Street [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument Principal Amount Subject To Repurchase | 13,056 |  |  |  |  |  |  |  |  |  | 13,056 |  |  |
Debt Instrument, Face Amount | $ 28,039 |  |  |  |  |  |  |  |  |  | $ 28,039 |  |  |
Extinguishment of Debt, Amount |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,043 |
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 8.40% |  |  |  |  |  |  |  |  |  | 8.40% |  |  |
Predecessor [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  |  |  |  | 155,271 |  |  |  |  |
Net realized gains (losses) on extinguishment of debt |  |  |  |  |  |  |  |  | $ 0 |  |  |  |  |
Predecessor [Member] | 5.1% Surplus Notes, General Account, Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  |  |  |  |  |  |  | 53.90% |  |  |  |  |
Predecessor [Member] | 5.1% Surplus Notes, Segregated Account, Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  |  |  |  |  |  |  | 52.80% |  |  |  |  |
Predecessor [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  |  |  |  |  |  |  | 58.30% |  |  |  |  |
Successor [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | $ 1,124,950 |  |  |  | 971,116 |  |  |  | $ 940,313 |  | $ 1,124,950 | 971,116 |  |
Net realized gains (losses) on extinguishment of debt | 0 | $ 1,420 | $ (1,246) | $ (93) | (74,724) | $ 0 | $ 0 | $ 0 |  | $ 0 | 81 | (74,724) |  |
Successor [Member] | Ambac Assurance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 1,124,950 |  |  |  | 971,116 |  |  |  |  |  | 1,124,950 | 971,116 |  |
Successor [Member] | Ambac Assurance Corporation [Member] | 5.1% Surplus Notes, General Account, Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 715,211 |  |  |  | 696,330 |  |  |  |  |  | 715,211 | 696,330 |  |
Successor [Member] | Ambac Assurance Corporation [Member] | 5.1% Surplus Notes, Segregated Account, Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 31,725 |  |  |  | 30,479 |  |  |  |  |  | 31,725 | 30,479 |  |
Successor [Member] | Ambac Assurance Corporation [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt | 247,443 |  |  |  | $ 244,307 |  |  |  |  |  | 247,443 | $ 244,307 |  |
Successor [Member] | Variable Interest Entities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  | 6.65% |  |  |  |  |  |  | 6.65% |  |
Long-term debt | $ 12,327,960 |  |  |  | $ 12,882,076 |  |  |  |  |  | $ 12,327,960 | $ 12,882,076 |  |
Successor [Member] | 5.1% Surplus Notes, General Account, Due 2020 [Member] | Ambac Assurance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.10% |  |  |  | 5.10% |  |  |  |  |  | 5.10% | 5.10% |  |
Debt Instruments Maturity Year |  |  |  |  |  |  |  |  |  |  | 2020 | 2020 |  |
Successor [Member] | 5.1% Surplus Notes, Segregated Account, Due 2020 [Member] | Ambac Assurance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.10% |  |  |  | 5.10% |  |  |  |  |  | 5.10% | 5.10% |  |
Debt Instruments Maturity Year |  |  |  |  |  |  |  |  |  |  | 2020 | 2020 |  |
Successor [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] | Ambac Assurance Corporation [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.10% |  |  |  | 5.10% |  |  |  |  |  | 5.10% | 5.10% |  |
Debt Instruments Maturity Year |  |  |  |  |  |  |  |  |  |  | 2020 | 2020 |  |
Consolidated Variable Interest Entities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unpaid Principal Amount Of Fixed Rate Debt Accounted For Under Fair Value Option | $ 10,803,729 |  |  |  | $ 11,925,499 |  |  |  |  |  | $ 10,803,729 | $ 11,925,499 |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months | 0 |  |  |  |  |  |  |  |  |  | 0 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Two | 0 |  |  |  |  |  |  |  |  |  | 0 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Three | 153,978 |  |  |  |  |  |  |  |  |  | 153,978 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Four | 363,498 |  |  |  |  |  |  |  |  |  | 363,498 |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Five | $ 60,665 |  |  |  |  |  |  |  |  |  | $ 60,665 |  |  |
Consolidated Variable Interest Entities [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 0.96% |  |  |  | 0.69% |  |  |  |  |  | 0.96% | 0.69% |  |
Consolidated Variable Interest Entities [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 13.00% |  |  |  | 13.00% |  |  |  |  |  | 13.00% | 13.00% |  |
London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest Rate on Securities Issued by Delaware Trust |  |  |  |  |  |  |  |  |  |  | 2.80% |  |  |

X
- Definition Junior Surplus Notes issued by the Segregated Account of Ambac Assurance to Ambac upon Ambac'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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