Contracts Accounted for as Insurance - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of year	$ 1,298	$ 1,372
Less: Specialty insurance premium receivable	1	1
Financial guaranty insurance premiums receivable	1,297	1,371
Gross written premiums on new business, net of commissions	79	61
Gross premiums received, net of commissions	(64)	(83)
Adjustments:
Changes in the expected term and debt service assumptions	6	8
Accretion of discount, net of commissions on assumed business	7	6
Foreign exchange gain (loss) on remeasurement	20	(29)
FG insurance premiums receivable	1,345	1,334
Specialty insurance premium receivable	1	1
Ending balance	$ 1,346	$ 1,335