Financial Guaranty Insurance Losses - Reconciliation of Net Expected Loss to be Paid and Expensed (Details) - USD ($) $ in Millions		Sep. 30, 2015		Jun. 30, 2015	Dec. 31, 2014		Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W		$ 1,307	[1]	$ 1,510	$ 1,169	[1]	$ 933	$ 1,035	$ 982
Contra-paid, net	[2],[3]	6			(100)
Loss and LAE reserve, net of reinsurance	[4]	(918)			(721)
Other recoveries		5			13
Net expected loss to be expensed (present value)		387
Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be expensed (present value)		79
Financial Guarantee Insurance And Other Product Line [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W		1,145
Contra-paid, net		6
Salvage and subrogation recoverable, net of reinsurance		131
Loss and LAE reserve, net of reinsurance		(899)
Other recoveries		4
Net expected loss to be expensed (present value)	[5]	387
Financial Guarantee Insurance And Other Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Loss and LAE reserve, net of reinsurance		73			80
Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W		1,280
Loss and LAE reserve, net of reinsurance		(991)			$ (801)
Financial Guarantee Insurance And Other Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W		$ 135

[1] Includes expected LAE to be paid of $13 million as of September 30, 2015 and $16 million as of December 31, 2014.

[2] Excludes $120 million and $125 million of deferred premium revenue, and $35 million and $42 million of contra-paid related to FG VIEs as of September 30, 2015 and December 31, 2014, respectively.

[3] See Note 7, "Financial Guaranty Insurance Losses– Insurance Contracts' Loss Information" for an explanation of "contra-paid".

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

[5] Excludes $79 million as of September 30, 2015, related to consolidated FG VIEs.