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, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers	$ 7,132		$ 3,400
Reinsurance Recoverables Secured By Letters Of Credit Amount	32
Reinsurance Recoverable	8	[1]
Moody's Aaa [Member] | S&P AA+ [Member] | Overseas Private Investment Corporation [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers	324
Reinsurance Recoverables Secured By Letters Of Credit Amount	0
Reinsurance Recoverable	0	[1]
Moody's A2 or above [Member] | S&P A+ Or Above [Member] | Others [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers	126
Reinsurance Recoverables Secured By Letters Of Credit Amount	2
Reinsurance Recoverable	0	[1]
Mood'ys A3 Rating [Member] | S&P AA- [Member] | Assured Guaranty Corp [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers	2,630
Reinsurance Recoverables Secured By Letters Of Credit Amount	0
Reinsurance Recoverable	8	[1]
Moody's Baa 1 Rating [Member] | S&P AA- [Member] | Assured Guaranty Re Ltd [Member]
Aggregate Amount Of Insured Par Outstanding Ceded To Reinsurers	4,052
Reinsurance Recoverables Secured By Letters Of Credit Amount	30
Reinsurance Recoverable	$ 0	[1]

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