Financial Guarantee Insurance Contracts - Effect of Reinsurance on Premiums Written and Earned (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Premiums Written	$ (127)	$ (2)	$ 1
Assumed Reinsurance Premiums Written	0	0	0
Ceded Reinsurance Premiums Written	(104)	(35)	1
Premiums written, net of reinsurance	(23)	33	0
Direct Premiums Earned	126	62	65
Premiums Earned, Net	56	47	54
Assumed Reinsurance Premiums Earned	0	0	1
Ceded Reinsurance Premiums Earned	69	15	12
Reinsurance on premiums earned, Net	56	47	$ 54
Reinsurance Recoverable, Allowance for Credit Loss	$ 0	$ 0