Insurance Contracts - Premium Earned (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Insurance [Line Items]
Premiums Earned, Net	$ 15	$ 14	$ 29	$ 28
Direct Premiums Written	55	37	115	67
Direct Premiums Earned	52	30	98	53
Assumed Reinsurance Premiums Written	0	0	0	0
Assumed Reinsurance Premiums Earned	0	0	0	0
Ceded Premiums Written	100	27	142	46
Ceded Reinsurance Premiums Earned	37	16	69	24
Premiums Written, Net	(45)	9	(27)	21
Premiums Receivable, Net	$ 276		$ 276		$ 269
Estimated Future Premium Payments Weighted Average Discounted Rate	3.10%		3.10%		3.00%
Weighted average period of future premiums			7 years 10 months 24 days		8 years
Reportable Geographical Components [Member] \| United States [Member]
Insurance [Line Items]
Premiums Earned, Net	$ 12	10	$ 23	20
Reportable Geographical Components [Member] \| United Kingdom [Member]
Insurance [Line Items]
Premiums Earned, Net	3	3	5	7
Reportable Geographical Components [Member] \| Other International [Member]
Insurance [Line Items]
Premiums Earned, Net	$ 1	$ 1	$ 1	$ 2

Weighted average discounted rate of estimated future premium payments to be paid by the VIEs.

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Insurance [Line Items]

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Amount of earned premiums assumed from other entities.

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Amount of written premiums assumed from other entities.

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Amount of earned premiums ceded to other entities.

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Amount of written premiums ceded to other entities.

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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums written.

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Weighted average period over which premium receivable for financial guarantee insurance contracts is collected where premium is received over the contract period, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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The carrying amount as of the balance sheet date due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, net of the allowance for doubtful accounts.

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Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums written.

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