Financial Guaranty Insurance Losses - Reconciliation of Net Expected Loss to be Paid and Expensed (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	$ 1,169		$ 982		$ 677
Loss and LAE reserve, net of reinsurance	721	[1]	556	[1]
Other recoveries	13	[2]	15	[2]
Net expected loss to be expensed (present value)	318
Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be expensed (present value)	89
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Guarantor Obligations [Line Items]
Contra-paid, net	(100)	[3],[4]	39	[3],[4]
Financial Guarantee Insurance Product Line [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	989
Contra-paid, net	(100)
Salvage and subrogation recoverable, net of reinsurance	135
Loss and LAE reserve, net of reinsurance	719		554
Other recoveries	13	[2]
Net expected loss to be expensed (present value)	318	[5]
Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Loss and LAE reserve, net of reinsurance	80		103
Financial Guarantee Insurance 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	1,115
Loss and LAE reserve, net of reinsurance	799		657
Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	$ 126

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

[2] R&W recoverables recorded in other assets on the consolidated balance sheet.

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

[4] Excludes $125 million and $187 million deferred premium revenue and $42 million and $55 million of contra-paid related to FG VIEs as of December 31, 2014 and December 31, 2013, respectively.

[5] Excludes $89 million as of December 31, 2014 related to consolidated FG VIEs.