Contracts Accounted for as Credit Derivatives - Distribution of Credit Derivative Net Par Outstanding by Internal Rating (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Credit Derivatives
Net Par Outstanding	$ 3,117	$ 4,040
BIG
Credit Derivatives
Net Par Outstanding	58	63
Credit Concentration Risk | Derivative, Aggregate Notional Amount
Credit Derivatives
Net Par Outstanding	$ 3,117	$ 4,040
Percentage of installment premiums denominated in currencies other than the U.S. dollar	100.00%	100.00%
Credit Concentration Risk | Derivative, Aggregate Notional Amount | AAA
Credit Derivatives
Net Par Outstanding	$ 1,166	$ 1,503
Percentage of installment premiums denominated in currencies other than the U.S. dollar	37.40%	37.20%
Credit Concentration Risk | Derivative, Aggregate Notional Amount | AA
Credit Derivatives
Net Par Outstanding	$ 1,078	$ 1,283
Percentage of installment premiums denominated in currencies other than the U.S. dollar	34.50%	31.80%
Credit Concentration Risk | Derivative, Aggregate Notional Amount | A
Credit Derivatives
Net Par Outstanding	$ 245	$ 514
Percentage of installment premiums denominated in currencies other than the U.S. dollar	7.90%	12.70%
Credit Concentration Risk | Derivative, Aggregate Notional Amount | BBB
Credit Derivatives
Net Par Outstanding	$ 570	$ 677
Percentage of installment premiums denominated in currencies other than the U.S. dollar	18.30%	16.70%
Credit Concentration Risk | Derivative, Aggregate Notional Amount | BIG
Credit Derivatives
Net Par Outstanding	$ 58	$ 63
Percentage of installment premiums denominated in currencies other than the U.S. dollar	1.90%	1.60%