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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 | 6 Months Ended |  |  |  |
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Jun. 30, 2024 USD ($) | Jun. 30, 2024 GBP (£) | Jun. 30, 2024 EUR (€) | Jun. 30, 2023 USD ($) | Jun. 30, 2023 GBP (£) | Jun. 30, 2023 EUR (€) | Jun. 30, 2024 USD ($) | Jun. 30, 2023 USD ($) | Mar. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Mar. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Insurance [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Allowance for Doubtful Accounts, Premiums and Other Receivables | $ 3,000 |  |  | $ 5,000 |  |  | $ 3,000 | $ 5,000 | $ 3,000 | $ 4,000 | $ 5,000 | $ 5,000
Past Due Premiums Receivable | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Uncollectable premiums |  |  |  |  |  |  | 1,000 | 1,000 |  |  |  |
Other adjustments (including foreign exchange) |  |  |  |  |  |  | (1,000) | 4,000 |  |  |  |
Premium Receivable, Allowance for Credit Loss | 3,000 |  |  |  |  |  | 3,000 |  |  | 4,000 |  |
Premium Receivable, Credit Loss Expense (Reversal) | 0 |  |  | (1,000) |  |  | (2,000) | (1,000) |  |  |  |
Premium Receivable, Allowance for Credit Loss, Writeoff | 0 |  |  | 0 |  |  | 0 | 0 |  |  |  |
Premium Receivable, Allowance for Credit Loss, Recovery | 0 |  |  | 0 |  |  | 0 | 0 |  |  |  |
Financing Receivable, 90 Days or More Past Due, Still Accruing | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Premiums Receivable, Gross | 317,000 |  |  | 276,000 |  |  | 317,000 | 276,000 |  | 290,000 |  | 269,000
Premiums Written, Gross |  |  |  |  |  |  | 159,000 |  |  |  |  |
Proceeds from Insurance Premiums Collected |  |  |  |  |  |  | (134,000) | (90,000) |  |  |  |
Adjustments for changes in expected and contractual cash flows |  |  |  |  |  |  | (2,000) | 6,000 |  |  |  |
Accretion of premium receivable discount |  |  |  |  |  |  | 4,000 | 4,000 |  |  |  |
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | 1,419,000 |  |  | 1,303,000 |  |  | 1,419,000 | 1,303,000 | $ 1,418,000 | 1,415,000 | $ 1,307,000 | $ 1,305,000
Premiums Receivable, Net | 317,000 |  |  |  |  |  | 317,000 |  |  | 290,000 |  |
Fair Value, Recurring [Member] | Loans Receivable [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Written, Gross |  |  |  |  |  |  |  | 83,000 |  |  |  |
Loans | 1,000 |  |  |  |  |  | 1,000 |  |  | 2,000 |  |
Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Other investments | 153,000 |  |  |  |  |  | 153,000 |  |  | 77,000 |  |
Loans | 2,000 |  |  |  |  |  | 2,000 |  |  | 2,000 |  |
Real Estate [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Other investments |  |  |  |  |  |  |  |  |  | 21,000 |  |
Real Estate [Member] | Foreign Exchange |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Other adjustments (including foreign exchange) |  |  |  |  |  |  | (1,000) | 4,000 |  |  |  |
Specialty Property & Casualty Program |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 85,000 |  |  |  |  |  | 85,000 |  |  | 46,000 |  |
Financial Guarantee |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 235,000 |  |  |  |  |  | 235,000 |  |  | 248,000 |  |
Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 135,000 |  |  |  |  |  | 135,000 |  |  | 140,000 |  |
Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 17,000 |  |  |  |  |  | 17,000 |  |  | 22,000 |  |
International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 82,000 |  |  |  |  |  | 82,000 |  |  | 85,000 |  |
I/SL [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 209,000 |  |  |  |  |  | 209,000 |  |  | 210,000 |  |
I/SL [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 128,000 |  |  |  |  |  | 128,000 |  |  | 133,000 |  |
I/SL [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 4,000 |  |
I/SL [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 77,000 |  |  |  |  |  | 77,000 |  |  | 72,000 |  |
IA [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 8,000 |  |  |  |  |  | 8,000 |  |  | 16,000 |  |
IA [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 3,000 |  |
IA [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
IA [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 5,000 |  |  |  |  |  | 5,000 |  |  | 13,000 |  |
II [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 5,000 |  |  |  |  |  | 5,000 |  |  | 5,000 |  |
II [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 5,000 |  |  |  |  |  | 5,000 |  |  | 5,000 |  |
II [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
II [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
III [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 7,000 |  |
III [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
III [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 7,000 |  |
III [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
IV [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 10,000 |  |  |  |  |  | 10,000 |  |  | 11,000 |  |
IV [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
IV [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 10,000 |  |  |  |  |  | 10,000 |  |  | 11,000 |  |
IV [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
United Kingdom, Pounds |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Ending premium receivable | 70,000 | £ 55 |  | 76,000 | £ 60 |  | 70,000 | 76,000 |  |  |  |
Euro Member Countries, Euro |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Ending premium receivable | 12,000 |  | € 11 | $ 14,000 |  | € 12 | 12,000 | $ 14,000 |  |  |  |
Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 1,000 |  |  |  |  |  | 1,000 |  |  | 1,000 |  |
Other Public Finance Sectors [Member] | I/SL [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 1,000 |  |  |  |  |  | 1,000 |  |  | 1,000 |  |
Other Public Finance Sectors [Member] | IA [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other Public Finance Sectors [Member] | II [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other Public Finance Sectors [Member] | III [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other Public Finance Sectors [Member] | IV [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other International [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 3,000 |  |
Other International [Member] | I/SL [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 3,000 |  |
Other International [Member] | IA [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other International [Member] | II [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other International [Member] | III [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other International [Member] | IV [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Mortgage Backed And Home Equity [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 11,000 |  |  |  |  |  | 11,000 |  |  | 12,000 |  |
Mortgage Backed And Home Equity [Member] | I/SL [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Mortgage Backed And Home Equity [Member] | IA [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Mortgage Backed And Home Equity [Member] | II [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Mortgage Backed And Home Equity [Member] | III [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Mortgage Backed And Home Equity [Member] | IV [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 10,000 |  |  |  |  |  | 10,000 |  |  | 11,000 |  |
Student Loans [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 4,000 |  |  |  |  |  | 4,000 |  |  | 7,000 |  |
Student Loans [Member] | I/SL [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Student Loans [Member] | IA [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Student Loans [Member] | II [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Student Loans [Member] | III [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 7,000 |  |
Student Loans [Member] | IV [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 1,000 |  |  |  |  |  | 1,000 |  |  | 0 |  |
Other Structured Finance [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 4,000 |  |
Other Structured Finance [Member] | I/SL [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 4,000 |  |
Other Structured Finance [Member] | IA [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other Structured Finance [Member] | II [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other Structured Finance [Member] | III [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Other Structured Finance [Member] | IV [Member] | Structured Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Sovereign And Sub Sovereign [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 63,000 |  |  |  |  |  | 63,000 |  |  | 64,000 |  |
Sovereign And Sub Sovereign [Member] | I/SL [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 58,000 |  |  |  |  |  | 58,000 |  |  | 51,000 |  |
Sovereign And Sub Sovereign [Member] | IA [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 5,000 |  |  |  |  |  | 5,000 |  |  | 13,000 |  |
Sovereign And Sub Sovereign [Member] | II [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Sovereign And Sub Sovereign [Member] | III [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Sovereign And Sub Sovereign [Member] | IV [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Investor Owned And Public Utilities [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  | 18,000 |  |
Investor Owned And Public Utilities [Member] | I/SL [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 16,000 |  |  |  |  |  | 16,000 |  |  | 18,000 |  |
Investor Owned And Public Utilities [Member] | IA [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Investor Owned And Public Utilities [Member] | II [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Investor Owned And Public Utilities [Member] | III [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Investor Owned And Public Utilities [Member] | IV [Member] | International Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Housing Revenue [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 134,000 |  |  |  |  |  | 134,000 |  |  | 139,000 |  |
Housing Revenue [Member] | I/SL [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 127,000 |  |  |  |  |  | 127,000 |  |  | 131,000 |  |
Housing Revenue [Member] | IA [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 3,000 |  |  |  |  |  | 3,000 |  |  | 3,000 |  |
Housing Revenue [Member] | II [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 5,000 |  |  |  |  |  | 5,000 |  |  | 5,000 |  |
Housing Revenue [Member] | III [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | 0 |  |  |  |  |  | 0 |  |  | 0 |  |
Housing Revenue [Member] | IV [Member] | Public Finance [Member] |  |  |  |  |  |  |  |  |  |  |  |
Financial Guarantee Insurance Contracts, Premium Receivable [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Receivable, Gross | $ 0 |  |  |  |  |  | $ 0 |  |  | $ 0 |  |

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- 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 -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-4 + Details
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- 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://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(5) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-3 + Details
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- Definition Amount of accretion of the discount for premiums receivable on financial guarantee insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-3 + Details
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- 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://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(4)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-3 + Details
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- Definition Amount of increase (decrease) in the premiums receivable on financial guarantee insurance contracts from adjustments classified as other. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iv) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-3 + Details
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- Definition Amortized cost of financing receivable 90 days or more past due and still accruing. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 80 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479294/326-20-55-80 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-16 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Subparagraph (b) -SubTopic 10 -Topic 310 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-7 + Details
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- Definition Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Publisher FASB -URI https://asc.fasb.org//310-10/tableOfContent + Details
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