XML 84 R65.htm IDEA: XBRL DOCUMENT
v3.19.1

Investments - Summary of Amortized Cost and Estimated Fair Value of Available-for-Sale Investments, Excluding VIE Investments (Detail) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | $ 3,472,642 | $ 3,451,149
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 147,650 | 133,052
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 283,413 | 1,139,101
Non - credit other - than - temporary Impairments | 123 | 32
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 2,800 | 27,298
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 424,000 | 359,943
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 5,545 | 10,897
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 8,345 | 38,195
Available-for-sale Securities, Current | 3,611,947 | 3,546,006
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 3,611,947 |
Short-term Investments [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 908,209 | 430,405
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 43 | 23
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 99,429 | 115,374
Non - credit other - than - temporary Impairments | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 17 | 97
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 17 | 97
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 908,235 | 430,331
Fixed Income Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 2,480,532 | 3,020,744
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 147,607 | 133,029
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 183,984 | 1,023,727
Non - credit other - than - temporary Impairments | 123 | 32
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 2,783 | 27,201
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 424,000 | 359,943
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 5,545 | 10,897
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 8,328 | 38,098
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 2,619,811 | 3,115,675
Fixed Income Securities [Member] | Municipal Bonds [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 406,315 | 882,631
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 20,356 | 14,364
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 20,997 | 537,904
Non - credit other - than - temporary Impairments | 0 | 5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 951 | 15,878
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 25,865 | 28,533
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 836 | 1,198
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 1,787 | 17,076
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 424,884 | 879,919
Fixed Income Securities [Member] | Corporate Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 1,223,640 | 1,288,882
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 14,312 | 6,444
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 39,639 | 306,506
Non - credit other - than - temporary Impairments | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 550 | 8,634
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 256,406 | 190,273
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 3,858 | 8,570
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 4,408 | 17,204
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 1,233,544 | 1,278,122
Fixed Income Securities [Member] | Foreign Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 30,719 | 30,496
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 599 | 399
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 401 | 1,161
Non - credit other - than - temporary Impairments | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 4 | 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 3,980 | 5,163
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 22 | 60
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 26 | 61
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 31,292 | 30,834
Fixed Income Securities [Member] | US Government Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 99,808 | 93,636
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 1,185 | 1,371
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 12,793 | 5,643
Non - credit other - than - temporary Impairments |  | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 360 | 135
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 53,861 | 58,495
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 204 | 478
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 564 | 613
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 100,429 | 94,394
Fixed Income Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 216,904 | 221,825
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 39,504 | 37,575
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 4,375 | 34,852
Non - credit other - than - temporary Impairments | 123 | 27
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 122 | 793
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 243 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 1 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 123 | 793
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 256,285 | 258,607
Fixed Income Securities [Member] | Collateralized Debt Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 133,736 | 133,075
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 28 | 8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 101,939 | 123,848
Non - credit other - than - temporary Impairments | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 787 | 1,727
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 787 | 1,727
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 132,977 | 131,356
Fixed Income Securities [Member] | Asset-backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 369,410 | 370,199
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 71,623 | 72,868
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 3,840 | 13,813
Non - credit other - than - temporary Impairments | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 9 | 33
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 83,645 | 77,479
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 624 | 591
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 633 | 624
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 440,400 | 442,443
Fixed Income Investments And Other Investments [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 3,388,741 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 147,650 |
Non - credit other - than - temporary Impairments | 123 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 8,345 |
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 3,528,046 |
Collateral Pledged [Member] | Fixed Income Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 83,901 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 |
Non - credit other - than - temporary Impairments | 0 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 0 |
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 83,901 | $ 0
Collateral Pledged [Member] | Fixed Income Securities [Member] | US Government Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | 83,901 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 0 |
Non - credit other - than - temporary Impairments | 0 |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 0 |
Fixed income securities, at fair value (amortized cost of $2,480,532 and $3,020,744) | 83,901 |
Asset Pledged as Collateral [Member] | Fixed Income Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Amortized Cost | $ 83,901 |

X
- Definition Accumulated other comprehensive loss related to portion of other than temporary impairment (OTTI) due to factors other than credit losses on debt securities categorized as available-for-sale that an entity does not intend to sell and which it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis of the debt security. The amount represented by this item is net of tax, as applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 9A -URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284427-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aaa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580 + Details
Name: | us-gaap_AccumulatedOtherComprehensiveIncomeLossOtherThanTemporaryImpairmentNotCreditLossNetOfTaxAvailableforsaleDebtSecurities
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 investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
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 investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26610-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
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_FinancialInstrumentAxis=us-gaap_ShortTermInvestmentsMember
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_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

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

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=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: |

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_AssetPledgedAsCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |