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Business and Basis of Presentation - Additional Information (Details) $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 01, 2023 rISK	May 31, 2024 USD ($)	Sep. 30, 2024 USD ($) Company	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)
Long-Lived Assets Held-for-sale [Line Items]
Number of holding companies with outstanding public debt | Company			2
Assured Guaranty Municipal Corp.
Long-Lived Assets Held-for-sale [Line Items]
Stock redeemed or during period		$ 100
Insurance licenses, writeoff			$ 6
AGC
Long-Lived Assets Held-for-sale [Line Items]
Stock redeemed or during period			300
Proceeds in exchange for redemption of common stock			167
Consolidated Investment Vehicles
Long-Lived Assets Held-for-sale [Line Items]
Number of remaining CIVs | rISK	3
Sound Point Agreement
Long-Lived Assets Held-for-sale [Line Items]
Assets held for sale				$ 4,700	$ 4,700
Liabilities held for sale				4,400	4,400
Disposal Group, Held-for-sale, Not Discontinued Operations
Long-Lived Assets Held-for-sale [Line Items]
Assets held for sale			28
Liabilities held for sale			$ 3
Disposal Group, Held-for-sale, Not Discontinued Operations | Sound Point Agreement
Long-Lived Assets Held-for-sale [Line Items]
Participation percentage	30.00%
Term to make new investments			2 years
Term to reinvest all returns of capital	15 years
Expenses recognized				$ 14	$ 46

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