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Business and Basis of Presentation - Narrative (Details) $ in Millions		1 Months Ended	3 Months Ended		12 Months Ended
	Jul. 01, 2023 USD ($) consolidatedInvestmentVehicle	May 31, 2024 USD ($)	Dec. 31, 2024 USD ($) Company	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) Company	Dec. 31, 2023 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of holding companies having outstanding public debt | Company			2		2
Assured Guaranty Municipal Corp.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Insurance licenses, writeoff				$ 6
Stock redeemed or during period		$ 100
AG (U.S. domiciled)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock redeemed or during period				300
Proceeds in exchange for redemption of common stock				$ 167
Consolidated investment vehicles
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of remaining entities | consolidatedInvestmentVehicle	3
Sound Point Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets						$ 4,700
Liabilities						4,400
Disposal Group, Held-for-Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets			$ 28		$ 28
Liabilities			$ 3		3
Disposal Group, Held-for-Sale, Not Discontinued Operations | Sound Point Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration, equity interest, ownership percentage	30.00%
Term to make new investments	2 years		2 years
Investment management commitment	$ 1,000				$ 1,000
Term to reinvest all returns of capital	15 years
Operating expense						$ 46

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