XML 107 R85.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Investments - Summary of Amortized Cost and Estimated Fair Value of Available-for-Sale Investments, Excluding VIE Investments (Detail) - Successor [Member] - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | $ 5,271,818 | $ 5,931,045
Gross Unrealized Gains | 145,386 | 198,505
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 108,043 | 79,642
Estimated Fair Value | 5,309,161 | 6,049,908
Non - credit other - than - temporary Impairments | 23,832 | 35,232
Below Investment Grade Securities and Non-Rated Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Below Investment Grade Securities And Non Rated Securities Continuous Unrealized Loss Position Aggregate Losses | 100,503 | 53,273
Below Investment Grade Securities And Non Rated Securities Continuous Unrealized Loss Position Fair Value | 1,855,694 | 890,952
Corporate Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Estimated Fair Value | 2,914,145 | 2,622,566
Short-Term [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 557,476 | 430,827
Gross Unrealized Gains | 3 | 5
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 209 | 44
Estimated Fair Value | 557,270 | 430,788
Non - credit other - than - temporary Impairments | 0 | 0
Ambac Wrapped Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 30,482 |
Fixed Income Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 4,614,623 | 5,435,385
Gross Unrealized Gains | 145,383 | 198,428
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 107,834 | 79,598
Estimated Fair Value | 4,652,172 | 5,554,215
Non - credit other - than - temporary Impairments | 23,832 | 35,232
Fixed Income Securities [Member] | Securities Pledged as Collateral [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 99,719 | 64,833
Gross Unrealized Gains | 0 | 72
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 0 | 0
Estimated Fair Value | 99,719 | 64,905
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 845,778 | 376,064
Gross Unrealized Gains | 3,456 | 5,509
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 69,400 | 7,205
Estimated Fair Value | 779,834 | 374,368
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | Corporate Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 858,774 | 1,803,136
Gross Unrealized Gains | 6,772 | 19,589
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 5,471 | 20,560
Estimated Fair Value | 860,075 | 1,802,165
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | Foreign Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 26,245 | 41,932
Gross Unrealized Gains | 409 | 1,303
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 111 | 100
Estimated Fair Value | 26,543 | 43,135
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | U.S. Government Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 86,900 | 33,732
Gross Unrealized Gains | 261 | 2,551
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 1,753 | 97
Estimated Fair Value | 85,408 | 36,186
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | U.S. Government Obligations [Member] | Securities Pledged as Collateral [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 99,719 | 64,833
Gross Unrealized Gains | 0 | 72
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 0 | 0
Estimated Fair Value | 99,719 | 64,905
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | U.S. Agency Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost |  | 4,063
Gross Unrealized Gains |  | 0
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments |  | 3
Estimated Fair Value |  | 4,060
Non - credit other - than - temporary Impairments |  | 0
Fixed Income Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 2,214,512 | 2,284,425
Gross Unrealized Gains | 67,303 | 110,955
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 30,482 | 43,785
Estimated Fair Value | 2,251,333 | 2,351,595
Non - credit other - than - temporary Impairments | 23,832 | 35,232
Fixed Income Securities [Member] | Collateralized Debt Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 50,754 | 113,650
Gross Unrealized Gains | 283 | 493
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 0 | 220
Estimated Fair Value | 51,037 | 113,923
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Securities [Member] | Asset-backed Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 531,660 | 778,383
Gross Unrealized Gains | 66,899 | 58,028
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 617 | 7,628
Estimated Fair Value | 597,942 | 828,783
Non - credit other - than - temporary Impairments | 0 | 0
Fixed Income Investments And Other Investments [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Amortized Cost | 5,172,099 | 5,866,212
Gross Unrealized Gains | 145,386 | 198,433
Available For Sale Securities Gross Unrealized Loss Accumulated In Investments | 108,043 | 79,642
Estimated Fair Value | 5,209,442 | 5,985,003
Non - credit other - than - temporary Impairments | $ 23,832 | $ 35,232

X
- Definition Aggregate losses of below investment grade securities and non rated securities in a continuous unrealized loss position. + References No definition available. + Details
Name: | ambc_BelowInvestmentGradeSecuritiesAndNonRatedSecuritiesContinuousUnrealizedLossPositionAggregateLosses
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of below investment grade securities and non rated securities in a continuous unrealized loss position. + References No definition available. + Details
Name: | ambc_BelowInvestmentGradeSecuritiesAndNonRatedSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Non credit other than temporary impairments on investments. + References No definition available. + Details
Name: | ambc_NonCreditOtherThanTemporaryImpairmentsOnInvestments
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_SuccessorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=ambc_BelowInvestmentGradeSecuritiesAndNonRatedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=ambc_AmbacWrappedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_FixedIncomeSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_SecuritiesPledgedAsCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ambc_FixedIncomeInvestmentsAndOtherInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |