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Financial Guarantee Insurance Contracts Financial Guarantee Insurance Contracts Earned Premiums by Geographic Location (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Premiums Earned, Net, Financial Guarantee Insurance Contracts | $ 54 | $ 66 | $ 111
Premiums Receivable, Gross | 387 |  |
Public Finance [Member] |  |  |
Premiums Receivable, Gross | 185 |  |
Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 59 |  |
International Finance [Member] |  |  |
Premiums Receivable, Gross | 144 |  |
Housing Revenue [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 168 |  |
Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 17 |  |
Mortgage-backed and Home Equity [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 22 |  |
Student Loan [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 16 |  |
Structured Insurance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 14 |  |
Other Structured Finance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 7 |  |
Sovereign/Sub-sovereign [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 108 |  |
Investor-owned and Public Utilities [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 31 |  |
Other International [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 5 |  |
Surveillance Category One [Member] |  |  |
Premiums Receivable, Gross | 302 |  |
Surveillance Category One [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 157 |  |
Surveillance Category One [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 27 |  |
Surveillance Category One [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 118 |  |
Surveillance Category One [Member] | Housing Revenue [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 155 |  |
Surveillance Category One [Member] | Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 2 |  |
Surveillance Category One [Member] | Mortgage-backed and Home Equity [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 3 |  |
Surveillance Category One [Member] | Student Loan [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 3 |  |
Surveillance Category One [Member] | Structured Insurance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 14 |  |
Surveillance Category One [Member] | Other Structured Finance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 7 |  |
Surveillance Category One [Member] | Sovereign/Sub-sovereign [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 82 |  |
Surveillance Category One [Member] | Investor-owned and Public Utilities [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 31 |  |
Surveillance Category One [Member] | Other International [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 5 |  |
IA [Member] |  |  |
Premiums Receivable, Gross | 40 |  |
IA [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 27 |  |
IA [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IA [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 13 |  |
IA [Member] | Housing Revenue [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 13 |  |
IA [Member] | Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 15 |  |
IA [Member] | Mortgage-backed and Home Equity [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IA [Member] | Student Loan [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IA [Member] | Structured Insurance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IA [Member] | Other Structured Finance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IA [Member] | Sovereign/Sub-sovereign [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 13 |  |
IA [Member] | Investor-owned and Public Utilities [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IA [Member] | Other International [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] |  |  |
Premiums Receivable, Gross | 3 |  |
II [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 3 |  |
II [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Housing Revenue [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Mortgage-backed and Home Equity [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 1 |  |
II [Member] | Student Loan [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 2 |  |
II [Member] | Structured Insurance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Other Structured Finance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Sovereign/Sub-sovereign [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Investor-owned and Public Utilities [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
II [Member] | Other International [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] |  |  |
Premiums Receivable, Gross | 27 |  |
III [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 14 |  |
III [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 13 |  |
III [Member] | Housing Revenue [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] | Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] | Mortgage-backed and Home Equity [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 3 |  |
III [Member] | Student Loan [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 11 |  |
III [Member] | Structured Insurance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] | Other Structured Finance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] | Sovereign/Sub-sovereign [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 13 |  |
III [Member] | Investor-owned and Public Utilities [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
III [Member] | Other International [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] |  |  |
Premiums Receivable, Gross | 15 |  |
IV [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 15 |  |
IV [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Housing Revenue [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Other Public Finance Sectors [Member] | Public Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Mortgage-backed and Home Equity [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 15 |  |
IV [Member] | Student Loan [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Structured Insurance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Other Structured Finance [Member] | Structured Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Sovereign/Sub-sovereign [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Investor-owned and Public Utilities [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
IV [Member] | Other International [Member] | International Finance [Member] |  |  |
Premiums Receivable, Gross | 0 |  |
Reportable Geographical Components [Member] | UNITED STATES |  |  |
Premiums Earned, Net, Financial Guarantee Insurance Contracts | 32 | 55 | 88
Reportable Geographical Components [Member] | UNITED KINGDOM |  |  |
Premiums Earned, Net, Financial Guarantee Insurance Contracts | 24 | 17 | 19
Reportable Geographical Components [Member] | Other International [Member] |  |  |
Premiums Earned, Net, Financial Guarantee Insurance Contracts | $ (2) | $ (6) | $ 5

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