XML 115 R95.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Derivative Instruments - Summary of Location and Amount of Gains and Losses of Derivative Contracts (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Unrealized Gain (Loss) on Derivatives |  |  |  |  |  |  |  |  | $ (893) | $ 14,783 | $ 19,194
Derivative, Gain (Loss) on Derivative, Net | $ (44,716) | $ 17,583 | $ 8,932 | $ 25,191 | $ 31,544 | $ 4,163 | $ 40,692 | $ (462) | 6,990 | 75,937 | (30,167)
Derivative, Gain (Loss) on Derivatives, Total Net |  |  |  |  |  |  |  |  | 511,113 | (59,885) | (525,625)
Net gains (losses) on derivative contracts [Domain] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Realized Gains Losses And Other Settlements |  |  |  |  |  |  |  |  | 388 | 1,589 | 912
Unrealized Gain (Loss) on Derivatives |  |  |  |  |  |  |  |  | (893) | 14,783 | 19,194
Net gains (losses) on derivative contracts [Domain] | Credit Derivatives [Member] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | (505) | 16,372 | 20,106
Net gains (losses) on derivative contracts [Domain] | Interest Rate Swaps [Member] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | 600 | 48,870 | (50,082)
Net gains (losses) on derivative contracts [Domain] | Futures Contracts [Member] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | 6,895 | 10,695 | (191)
Income Loss On Variable Interest Entities [Member] | Variable Interest Entity [Member] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | 504,628 | (152,194) | (515,564)
Income Loss On Variable Interest Entities [Member] | Interest Rate Swaps [Member] | Variable Interest Entity [Member] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | 493,203 | (126,664) | (574,554)
Income Loss On Variable Interest Entities [Member] | Currency Swaps [Member] | Variable Interest Entity [Member] |  |  |  |  |  |  |  |  |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |  |  |  |  |  |  |  |  |
Derivative, Gain (Loss) on Derivative, Net |  |  |  |  |  |  |  |  | $ 11,425 | $ (25,530) | $ 58,990

X
- Definition Derivative, Gain (Loss) on Derivatives, Total Net + References No definition available. + Details
Name: | ambc_DerivativeGainLossonDerivativesTotalNet
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This element represents premiums received and receivable on credit derivative contracts, premiums paid and accrued on purchased contracts and net losses and settlements, that is included in earnings. + References No definition available. + Details
Name: | ambc_RealizedGainsLossesAndOtherSettlements
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
Name: | us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=ambc_NetgainslossesonderivativecontractsDomain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ambc_CreditDerivativesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_FutureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=ambc_IncomeLossOnVariableInterestEntitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CurrencySwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |