The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

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Amount, after premiums ceded to other entities and premiums assumed by the entity, of financial guarantee premiums earned.

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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.

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The estimated amount as of the balance sheet date to be received by an insurer from the sale of property (usually damaged) on which the insurer has paid a total claim to the insured and has obtained title to the property and the right of an insurer to pursue any course of recovery of damages, in its name or in the name of the policyholder, against a third party who is liable for costs relating to an insured event that have been paid by the insurer. Estimated salvage and subrogation is generally deducted from the liability for unpaid claims.

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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, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Premiums Earned, Net, Financial Guarantee Insurance Contracts	$ 78	$ 56	$ 47
Premiums Receivable, Gross	290	269	323	$ 370
Liability for Claims and Claims Adjustment Expense	893	805
Subrogation recoverable	137	271
Property and Casualty, Commercial Insurance
Liability for Claims and Claims Adjustment Expense	197	90
Public Finance [Member]
Premiums Receivable, Gross	140	150
Structured Finance [Member]
Premiums Receivable, Gross	22	24
International Finance [Member]
Premiums Receivable, Gross	85	85
Housing Revenue [Member] \| Public Finance [Member]
Premiums Receivable, Gross	139	148
Other Public Finance Sectors [Member] \| Public Finance [Member]
Premiums Receivable, Gross	1	2
Mortgage-backed and Home Equity [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	12	11
Student Loan [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	7	8
Other Structured Finance [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	4	4
Sovereign/Sub-sovereign [Member] \| International Finance [Member]
Premiums Receivable, Gross	64	64
Investor-owned and Public Utilities [Member] \| International Finance [Member]
Premiums Receivable, Gross	18	18
Other International [Member] \| International Finance [Member]
Premiums Receivable, Gross	3	2
Surveillance Category One [Member]
Premiums Receivable, Gross	210	217
Surveillance Category One [Member] \| Public Finance [Member]
Premiums Receivable, Gross	133	142
Surveillance Category One [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	4	5
Surveillance Category One [Member] \| International Finance [Member]
Premiums Receivable, Gross	72	70
Surveillance Category One [Member] \| Housing Revenue [Member] \| Public Finance [Member]
Premiums Receivable, Gross	131	140
Surveillance Category One [Member] \| Other Public Finance Sectors [Member] \| Public Finance [Member]
Premiums Receivable, Gross	1	2
Surveillance Category One [Member] \| Mortgage-backed and Home Equity [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
Surveillance Category One [Member] \| Student Loan [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	1
Surveillance Category One [Member] \| Other Structured Finance [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	4	4
Surveillance Category One [Member] \| Sovereign/Sub-sovereign [Member] \| International Finance [Member]
Premiums Receivable, Gross	51	49
Surveillance Category One [Member] \| Investor-owned and Public Utilities [Member] \| International Finance [Member]
Premiums Receivable, Gross	18	18
Surveillance Category One [Member] \| Other International [Member] \| International Finance [Member]
Premiums Receivable, Gross	3	2
IA [Member]
Premiums Receivable, Gross	16	10
IA [Member] \| Public Finance [Member]
Premiums Receivable, Gross	3	3
IA [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	1
IA [Member] \| International Finance [Member]
Premiums Receivable, Gross	13	7
IA [Member] \| Housing Revenue [Member] \| Public Finance [Member]
Premiums Receivable, Gross	3	3
IA [Member] \| Other Public Finance Sectors [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
IA [Member] \| Mortgage-backed and Home Equity [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
IA [Member] \| Student Loan [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	1
IA [Member] \| Other Structured Finance [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
IA [Member] \| Sovereign/Sub-sovereign [Member] \| International Finance [Member]
Premiums Receivable, Gross	13	7
IA [Member] \| Investor-owned and Public Utilities [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
IA [Member] \| Other International [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
II [Member]
Premiums Receivable, Gross	5	5
II [Member] \| Public Finance [Member]
Premiums Receivable, Gross	5	5
II [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Housing Revenue [Member] \| Public Finance [Member]
Premiums Receivable, Gross	5	5
II [Member] \| Other Public Finance Sectors [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Mortgage-backed and Home Equity [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Student Loan [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Other Structured Finance [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Sovereign/Sub-sovereign [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Investor-owned and Public Utilities [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
II [Member] \| Other International [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
III [Member]
Premiums Receivable, Gross	7	16
III [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
III [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	7	7
III [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	9
III [Member] \| Housing Revenue [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
III [Member] \| Other Public Finance Sectors [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
III [Member] \| Mortgage-backed and Home Equity [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
III [Member] \| Student Loan [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	7	7
III [Member] \| Other Structured Finance [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
III [Member] \| Sovereign/Sub-sovereign [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	9
III [Member] \| Investor-owned and Public Utilities [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
III [Member] \| Other International [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member]
Premiums Receivable, Gross	11	11
IV [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	11	11
IV [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Housing Revenue [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Other Public Finance Sectors [Member] \| Public Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Mortgage-backed and Home Equity [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	11	11
IV [Member] \| Student Loan [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Other Structured Finance [Member] \| Structured Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Sovereign/Sub-sovereign [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Investor-owned and Public Utilities [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
IV [Member] \| Other International [Member] \| International Finance [Member]
Premiums Receivable, Gross	0	0
Reportable Geographical Components [Member] \| UNITED STATES
Premiums Earned, Net, Financial Guarantee Insurance Contracts	65	41	27
Reportable Geographical Components [Member] \| UNITED KINGDOM
Premiums Earned, Net, Financial Guarantee Insurance Contracts	11	13	14
Reportable Geographical Components [Member] \| Other International [Member]
Premiums Earned, Net, Financial Guarantee Insurance Contracts	$ 2	$ 3	$ 6