Financial Guaranty Insurance - Loss and LAE Reserve and Salvage and Subrogation Recoverable Net of Reinsurance (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	[1]	$ 998	$ 721
Salvage and Subrogation Recoverable, net	[1]	126	154
Net Reserve (Recoverable)	[1]	872	567
Financial Guarantee Insurance And Other Product Line [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		982
Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		1,072	801
Salvage and Subrogation Recoverable, net		126	155
Net Reserve (Recoverable)		946	646
Financial Guarantee Insurance And Other Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		(74)	(80)
Salvage and Subrogation Recoverable, net		0	(1)
Net Reserve (Recoverable)		(74)	(79)
XXX Life Insurance Transaction [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		82	140
Salvage and Subrogation Recoverable, net		0	0
Net Reserve (Recoverable)		82	140
Trust preferred securities (TruPS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		0	0
Salvage and Subrogation Recoverable, net		0	0
Net Reserve (Recoverable)		0	0
Student Loan [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		51	64
Salvage and Subrogation Recoverable, net		0	0
Net Reserve (Recoverable)		51	64
Other structured finance [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		48	34
Salvage and Subrogation Recoverable, net		0	8
Net Reserve (Recoverable)		48	26
Structured Finance [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		443	528
Salvage and Subrogation Recoverable, net		116	134
Net Reserve (Recoverable)		327	394
Financial Guarantee [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		1,072	801
Salvage and Subrogation Recoverable, net		123	142
Net Reserve (Recoverable)		949	659
Public Finance [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		629	273
Salvage and Subrogation Recoverable, net		7	8
Net Reserve (Recoverable)		622	265
Other [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		0	0
Salvage and Subrogation Recoverable, net		3	13
Net Reserve (Recoverable)		(3)	(13)
United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		262	290
Salvage and Subrogation Recoverable, net		116	126
Net Reserve (Recoverable)		146	164
United States [Member] | Public Finance [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		604	243
Salvage and Subrogation Recoverable, net		7	8
Net Reserve (Recoverable)		597	235
Non United States [Member] | Public Finance [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		25	30
Salvage and Subrogation Recoverable, net		0	0
Net Reserve (Recoverable)		25	30
First Lien [Member] | United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		230	283
Salvage and Subrogation Recoverable, net		63	48
Net Reserve (Recoverable)		167	235
Second Lien [Member] | United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		32	7
Salvage and Subrogation Recoverable, net		53	78
Net Reserve (Recoverable)		(21)	(71)
Financing Receivable, Prime [Member] | First Lien [Member] | United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		2	2
Salvage and Subrogation Recoverable, net		0	0
Net Reserve (Recoverable)		2	2
Alt-A [Member] | First Lien [Member] | United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		46	87
Salvage and Subrogation Recoverable, net		0	0
Net Reserve (Recoverable)		46	87
Option ARM [Member] | First Lien [Member] | United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		13	28
Salvage and Subrogation Recoverable, net		42	40
Net Reserve (Recoverable)		(29)	(12)
Subprime [Member] | First Lien [Member] | United States [Member] | Residential Mortgage-Backed Securities (RMBS) [Member] | Financial Guarantee Insurance And Other Product Line [Member] | Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net		169	166
Salvage and Subrogation Recoverable, net		21	8
Net Reserve (Recoverable)		$ 148	$ 158

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