Contracts Accounted for as Insurance - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Guarantor Obligations [Line Items]
Weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations	4.17%	4.15%
Gross	$ 398,037	$ 370,172
Gross Exposure	3,800
Puerto Rico
Guarantor Obligations [Line Items]
Gross	1,526	$ 1,899
Ceded Business
Guarantor Obligations [Line Items]
Insured financial obligations insured contractual payments outstanding, amount represented	$ 401
Insured financial obligations insured contractual payments outstanding, percentage represented	0.10%
Gross Insured Specialty and Reinsurance Business
Guarantor Obligations [Line Items]
Insured financial obligations insured contractual payments outstanding, amount represented	$ 482
Minimum
Guarantor Obligations [Line Items]
Risk free discount rate	3.79%	3.82%
Maximum
Guarantor Obligations [Line Items]
Risk free discount rate	5.40%	4.69%
Premiums Receivable | Foreign Currency Concentration Risk | Premiums Receivable
Guarantor Obligations [Line Items]
Percentage of installment premiums denominated in currencies other than the U.S. dollar	70.00%	74.00%