XML 59 R43.htm IDEA: XBRL DOCUMENT
v3.20.2

Financial Guarantee Insurance Contracts - Summary of Gross Premium Receivable Roll-Forward (Direct and Assumed Contracts) (Details) $ in Thousands, € in Millions, £ in Millions | 3 Months Ended | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2020 USD ($) | Sep. 30, 2020 GBP (£) | Sep. 30, 2020 EUR (€) | Sep. 30, 2019 USD ($) | Sep. 30, 2019 GBP (£) | Sep. 30, 2019 EUR (€) | Sep. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) | Jan. 01, 2020 USD ($) | Dec. 31, 2019 USD ($)
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Allowance for Doubtful Accounts, Premiums and Other Receivables | $ 18,000 |  |  |  |  |  | $ 18,000 |  | $ 16,000 |  | $ 9,000
Premiums Receivable, Gross | 390,000 |  |  |  |  |  | 390,000 |  |  |  |
Financial Guarantee Insurance Contracts, Accelerated Premium Revenue, Amount | 5,000 |  |  | $ 2,000 |  |  | 6,000 | $ 8,000 |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |
Beginning premium receivable |  |  |  |  |  |  | 416,000 | 495,000 |  |  |
Premium receipts |  |  |  |  |  |  | 36,000 | 37,000 |  |  |
Adjustments for changes in expected and contractual cash flows |  |  |  |  |  |  | (4,000) | (33,000) |  |  |
Accretion of premium receivable discount |  |  |  |  |  |  | 7,000 | 9,000 |  |  |
financial guarantee insurance contracts premium receivable deconsolidation of VIE |  |  |  |  |  |  |  | 3,000 |  |  |
Uncollectable premiums |  |  |  |  |  |  | (5,000) | (7,000) |  |  |
Other adjustments (including foreign exchange) |  |  |  |  |  |  | (2,000) | (16,000) |  |  |
Ending premium receivable | 372,000 |  |  | 415,000 |  |  | 372,000 | 415,000 |  |  |
Premium Receivable, Allowance for Credit Loss | 18,000 |  |  |  |  |  | 18,000 |  |  |  |
Premium Receivable, Credit Loss Expense (Reversal) | 2,000 |  |  |  |  |  | 9,000 |  |  |  |
Premium Receivable, Allowance for Credit Loss, Writeoff | 0 |  |  |  |  |  | 0 |  |  |  |
Premium Receivable, Allowance for Credit Loss, Recovery | 0 |  |  |  |  |  | 0 |  |  |  |
Financing Receivable, Past Due | 2,000 |  |  |  |  |  | 2,000 |  |  |  |
Financing Receivable, 90 Days or More Past Due, Still Accruing | 2,000 |  |  |  |  |  | 2,000 |  |  |  |
Reinsurance Recoverable, Allowance for Credit Loss | 0 |  |  |  |  |  | 0 |  |  |  |
United Kingdom, Pounds |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |
Ending premium receivable | 112,000 | £ 87 |  | 124,000 | £ 101 |  | 112,000 | 124,000 |  |  |
Euro Member Countries, Euro |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |
Ending premium receivable | 21,000 |  | € 18 | $ 22,000 |  | € 20 | 21,000 | $ 22,000 |  |  |
Accounting Standards Update 2016-13 [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption | (4,000) |  |  |  |  |  | (4,000) |  |  |  |
Premiums Receivable [Member] | Accounting Standards Update 2016-13 [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  |  |  |  |  |  |  | $ (3,000) |
Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 39,000 |  |  |  |  |  | 39,000 |  |  |  |
Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  |  |
Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 29,000 |  |  |  |  |  | 29,000 |  |  |  |
Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  |  |
Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 302,000 |  |  |  |  |  | 302,000 |  |  |  |
Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 63,000 |  |  |  |  |  | 63,000 |  |  |  |
Structured Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Structured Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  |  |
Structured Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 15,000 |  |  |  |  |  | 15,000 |  |  |  |
Structured Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  |  |
Structured Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 29,000 |  |  |  |  |  | 29,000 |  |  |  |
International Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 141,000 |  |  |  |  |  | 141,000 |  |  |  |
International Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 13,000 |  |  |  |  |  | 13,000 |  |  |  |
International Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
International Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 15,000 |  |  |  |  |  | 15,000 |  |  |  |
International Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
International Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 113,000 |  |  |  |  |  | 113,000 |  |  |  |
Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 186,000 |  |  |  |  |  | 186,000 |  |  |  |
Public Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 26,000 |  |  |  |  |  | 26,000 |  |  |  |
Public Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Public Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Public Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Public Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 160,000 |  |  |  |  |  | 160,000 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 13,000 |  |  |  |  |  | 13,000 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 2,000 |  |  |  |  |  | 2,000 |  |  |  |
Other International [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 6,000 |  |  |  |  |  | 6,000 |  |  |  |
Other International [Member] | International Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other International [Member] | International Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other International [Member] | International Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other International [Member] | International Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other International [Member] | International Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 6,000 |  |  |  |  |  | 6,000 |  |  |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 23,000 |  |  |  |  |  | 23,000 |  |  |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross |  |  |  |  |  |  |  |  |  |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 1,000 |  |  |  |  |  | 1,000 |  |  |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  |  |
Structured Insurance [Domain] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  |  |
Structured Insurance [Domain] | Structured Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Structured Insurance [Domain] | Structured Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Structured Insurance [Domain] | Structured Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Structured Insurance [Domain] | Structured Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Structured Insurance [Domain] | Structured Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  |  |
Student Loans [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 17,000 |  |  |  |  |  | 17,000 |  |  |  |
Student Loans [Member] | Structured Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Student Loans [Member] | Structured Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 2,000 |  |  |  |  |  | 2,000 |  |  |  |
Student Loans [Member] | Structured Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 12,000 |  |  |  |  |  | 12,000 |  |  |  |
Student Loans [Member] | Structured Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Student Loans [Member] | Structured Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  |  |
Other Structured Finance [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 7,000 |  |  |  |  |  | 7,000 |  |  |  |
Other Structured Finance [Member] | Structured Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Structured Finance [Member] | Structured Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Structured Finance [Member] | Structured Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Structured Finance [Member] | Structured Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Other Structured Finance [Member] | Structured Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 7,000 |  |  |  |  |  | 7,000 |  |  |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 105,000 |  |  |  |  |  | 105,000 |  |  |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 13,000 |  |  |  |  |  | 13,000 |  |  |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 15,000 |  |  |  |  |  | 15,000 |  |  |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 78,000 |  |  |  |  |  | 78,000 |  |  |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 29,000 |  |  |  |  |  | 29,000 |  |  |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 29,000 |  |  |  |  |  | 29,000 |  |  |  |
Housing Revenue [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 171,000 |  |  |  |  |  | 171,000 |  |  |  |
Housing Revenue [Member] | Public Finance [Member] | Surveillance Category Onea [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 13,000 |  |  |  |  |  | 13,000 |  |  |  |
Housing Revenue [Member] | Public Finance [Member] | Surveillance Category Two [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Housing Revenue [Member] | Public Finance [Member] | Surveillance Category Three [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Housing Revenue [Member] | Public Finance [Member] | Surveillance Category Four [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  |  |
Housing Revenue [Member] | Public Finance [Member] | Surveillance Category One [Member] |  |  |  |  |  |  |  |  |  |  |
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | $ 158,000 |  |  |  |  |  | $ 158,000 |  |  |  |

X
- Definition financial guarantee insurance contracts premium receivable deconsolidation of VIE + References No definition available. + Details
Name: | ambc_FinancialGuaranteeInsuranceContractsPremiumReceivableDeconsolidationOfVIE
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Insurance [Line Items] + References No definition available. + Details
Name: | ambc_InsuranceLineItems
Namespace Prefix: | ambc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The valuation allowance as of the balance sheet date to reduce the gross amount of receivables to estimated net realizable value, which would be presented in parentheses on the face of the balance sheet. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524 + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption. + References No definition available. + Details
Name: | us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This element represents the amount of premium revenue on financial guarantee insurance contracts recognized during the period that was accelerated for revenue recognition purposes. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsAcceleratedPremiumRevenueAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of the premium receivable for financial guarantee insurance contracts reported in the statement of financial position. This element primarily would consist of those financial guarantee insurance contracts which premiums are to be collected over the contract period, but may, on occasion, include premiums which are to be collected in full at inception, but which straddle a financial reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(1),(5) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash inflow from premiums received for premium receivable on financial guarantee insurance contracts. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 17 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3367-108585 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivableProceedsFromPremiumsReceived
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumReceivableRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of accretion of the discount for premiums receivable on financial guarantee insurance contracts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iii) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAccretionOfDiscountOnPremiumReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the premium receivable on financial guarantee insurance contracts from changes in the period of the contract. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(4)(i) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentChangeInPeriodOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) in the premiums receivable on financial guarantee insurance contracts from adjustments classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iv) -URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsPremiumsReceivableAdjustmentOtherAdjustments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of financing receivable 90 days or more past due and still accruing. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable past due. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of expense (reversal of expense) for expected credit loss on premium receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 + Details
Name: | us-gaap_PremiumReceivableCreditLossExpenseReversal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The carrying value as of the balance sheet date of the estimated valuation allowance to reduce gross premiums receivable to net realizable value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(5)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524 + Details
Name: | us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase (decrease) in allowance for credit loss on premium receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524 + Details
Name: | us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of recoveries of premiums receivable that were previously written off as bad debts. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 + Details
Name: | us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsRecoveries
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of writeoff of premium receivable, charged against allowance for credit loss. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524 + Details
Name: | us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsWriteOffsAgainstAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Gross amount, as of the balance sheet date, due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, before deducting the allowance for doubtful accounts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.5) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 + Details
Name: | us-gaap_PremiumsReceivableGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit loss on reinsurance recoverable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446 + Details
Name: | us-gaap_ReinsuranceRecoverablesAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | srt_CurrencyAxis=currency_GBP
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CurrencyAxis=currency_EUR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=us-gaap_AccountingStandardsUpdate201613Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_PremiumsReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ambc_SurveillanceCategoryOneaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ambc_SurveillanceCategoryTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ambc_SurveillanceCategoryThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ambc_SurveillanceCategoryFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ambc_SurveillanceCategoryOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_StructuredFinanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=ambc_InternationalFinanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=ambc_PublicFinanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_OtherPublicFinanceSectorsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_OtherInternationalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_MortgageBackedAndHomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_StructuredInsuranceDomain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_StudentLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_OtherStructuredFinanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_SovereignAndSubSovereignMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_InvestorOwnedAndPublicUtilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SecuritiesFinancingTransactionAxis=ambc_HousingRevenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |