Financial Guaranty Insurance Losses - Balance Sheet Classification of Net Expected Recoveries for Breaches of R&W Insurance Contracts (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Salvage and subrogation recoverable, net [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	[1]	$ (19)	$ 20
Salvage and subrogation recoverable, net [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts		0	0
Loss and LAE reserve, net [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	[1]	112	177
Loss and LAE reserve, net [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts		(7)	(8)
Financial Guarantee Insurance Product Line [Member] | Salvage and subrogation recoverable, net [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts		(19)	20
Financial Guarantee Insurance Product Line [Member] | Loss and LAE reserve, net [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts		$ 119	$ 185

[1] 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 total loss, net of R&W, exceeds unearned premium reserve.