Contracts Accounted for as Insurance - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of year	$ 1,372	$ 1,372	$ 1,286
Financial guaranty insurance premiums receivable	1,297	1,371	1,371	$ 1,284
Gross written premiums on new business, net of commissions	356	369	462
Gross premiums received, net of commissions	(345)	(383)	(426)
Adjustments:
Changes in the expected term and debt service assumptions	2	6	(10)
Accretion of discount, net of commissions on assumed business	24	26	18
Foreign exchange gain (loss) on remeasurement	(111)	(22)	43
Expected recovery of premiums previously written off	0	4	0
Specialty insurance premium receivable	1	1	1	$ 2
End of period	$ 1,298	$ 1,372	$ 1,372