Financial Guarantees in Force - Summary of International Finance Guaranteed Portfolio (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	$ 19,541	$ 22,613
International Finance [Member]
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	8,664	8,454
International Finance [Member] | United Kingdom [Member]
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	7,502	7,223
International Finance [Member] | Australia [Member]
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	266	259
International Finance [Member] | Italy [Member]
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	576	644
International Finance [Member] | AUSTRIA
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	307	310
International Finance [Member] | FRANCE
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	12	14
International Finance [Member] | Other International [Member]
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	1	4
International Finance [Member] | United States [Member]
Guarantor Obligations [Line Items]
Net Par Amount Outstanding	$ 10,877	$ 14,159