XML 90 R74.htm IDEA: XBRL DOCUMENT
v3.19.2

Investments - Summary of Net Investment Income (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Investment [Line Items] |  |  |  |
Net Realized and Unrealized Gain (Loss) on Trading Securities | $ 6,766 | $ 3,632 |  |
Trading Securities, Realized Gain (Loss) | 2,664 | 344 |  |
Investment expense | (1,471) | (1,374) | $ (2,882) | $ (3,200)
Securities available-for-sale and short-term | 78,329 | 61,742 | 124,881 | 172,293
Net investment income | 86,459 | 66,662 | 141,301 | 176,902
Gains (losses) on securities held as of reporting date [Member] |  |  |  |
Investment [Line Items] |  |  |  |
Net Realized and Unrealized Gain (Loss) on Trading Securities |  |  | 13,713 | 2,053
Trading Securities, Realized Gain (Loss) |  |  | 3,572 | 1,325
Other Investments Income | 4,102 | 3,288 | 10,141 | 728
Fixed Income Investments [Member] |  |  |  |
Investment [Line Items] |  |  |  |
Gross Investment Income, Operating | 74,137 | 60,499 | 117,803 | 169,848
Short-Term [Member] |  |  |  |
Investment [Line Items] |  |  |  |
Gross Investment Income, Operating | 5,481 | 2,438 | 9,594 | 5,278
Loans Receivable [Member] |  |  |  |
Investment [Line Items] |  |  |  |
Gross Investment Income, Operating | 182 | 179 | 366 | 367
Other Investments [Member] |  |  |  |
Investment [Line Items] |  |  |  |
Gross Investment Income, Operating | $ 8,130 | $ 4,920 | $ 16,420 | $ 4,609

X
- Definition Other Investments Income + References No definition available. + Details
Name: | ambc_OtherInvestmentsIncome
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent reporting 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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 12 -Sentence Column A + Details
Name: | invest_InvestmentLineItems
Namespace Prefix: | invest_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.2) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 + Details
Name: | us-gaap_GrossInvestmentIncomeOperating
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on available-for-sale securities. + References No definition available. + Details
Name: | us-gaap_InterestAndDividendIncomeSecuritiesAvailableForSale
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of expenses related to the generation of investment income. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.2) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 + Details
Name: | us-gaap_InvestmentIncomeInvestmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 + Details
Name: | us-gaap_NetInvestmentIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The sum of the realized and unrealized net gain (loss) on trading securities during the period. + References No definition available. + Details
Name: | us-gaap_NetRealizedOrUnrealizedGainLossOnTradingSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) realized from securities classified as trading. + References No definition available. + Details
Name: | us-gaap_TradingSecuritiesRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

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

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

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

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