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, 2015	Dec. 31, 2014
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers		$ 5,294	$ 6,100
Reinsurance Recoverables Secured By Letters Of Credit Amount		33
Reinsurance Recoverable	[1]	6
Assured Guaranty Corp [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers		1,673
Assured Guaranty Re Ltd [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers		3,251
Reinsurance Recoverables Secured By Letters Of Credit Amount		30
Reinsurance Recoverable	[1]	6
Overseas Private Investment Corporation [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers		250
Others [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers		120
Reinsurance Recoverables Secured By Letters Of Credit Amount		$ 3

[1] Total reinsurance recoverable is primarily related to recoverables on unpaid losses.