Financial Guaranty Insurance Losses (Components of Net Reserves (Salvage) Insurance Contracts) (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Guarantor Obligations [Line Items]
Loss and loss adjustment expense reserve	$ 532		$ 601
Reinsurance recoverable on unpaid losses	(56)		(58)
Subtotal	476	[1]	543	[1]
Salvage and subrogation recoverable	(543)		(456)
Ceded salvage and subrogation recoverable	50	[2]	46	[2]
Salvage and Subrogation Recoverable Payable, Net	(493)	[1]	(410)	[1]
Subtotal	(520)		(440)
Total Reserve for Losses and LAE, Net of Reinsurance, Salvage and Subrogation and Other Recoveries	(44)		103
Total	(17)	[1]	133	[1]
For all Financial Guaranty Insurance Contracts	600		449
Effect of Consolidating FG VIEs	(236)		(169)
Reported on Balance Sheet	364	[3]	280	[3]
For all Financial Guaranty Insurance Contracts	522		571
Effect of Consolidating FG VIEs	(39)		(33)
Reported on Balance Sheet	483	[3]	538	[3]
Consolidated Entity Excluding Variable Interest Entities (VIE)
Guarantor Obligations [Line Items]
Reinsurance recoverable on unpaid losses	(27)	[4]
Salvage and Subrogation Recoverable Payable, Net	(488)
Other recoveries	(27)	[4]	(30)	[4]
Other
Guarantor Obligations [Line Items]
Total	(3)		(3)
Financial guaranty
Guarantor Obligations [Line Items]
Total	$ (41)		$ 106

[1] (1)See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.

[2] Recorded as a component of reinsurance balances payable.

[3] The remaining benefit for R&W is either recorded at fair value in FG VIE assets, or not recorded on the balance sheet until the expected loss, net of R&W, exceeds unearned premium reserve.

[4] R&W recoveries recorded in other assets on the consolidated balance sheet.