Insurance In Force (Summary Of Company's Reinsurance Agreements For U.S. Public Finance And Structured Finance And International Insurance Operations) (Detail) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Ceded Par Outstanding		$ 1,017	$ 1,500
Letters of Credit/Trust Accounts		15
Reinsurance Recoverable/ (Payable)	[1]	(48)
Assured Guaranty Corp [Member]
Ceded Par Outstanding		463
Letters of Credit/Trust Accounts		0
Reinsurance Recoverable/ (Payable)	[1]	(45)
Assured Guaranty Re Ltd [Member]
Ceded Par Outstanding	[2]	503
Letters of Credit/Trust Accounts	[2]	15
Reinsurance Recoverable/ (Payable)	[1],[2]	(2)
Others [Member]
Ceded Par Outstanding	[2]	51
Letters of Credit/Trust Accounts	[2]	0
Reinsurance Recoverable/ (Payable)	[1],[2]	$ (1)

[1] Total reinsurance recoverable/(payable) is primarily related to recoverables on unpaid losses net of (payables) on salvage received.

[2] Represents a withdrawal of ratings.