Expected Losses to be Paid - Net Expected Loss to be Paid by Accounting Model (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013		Dec. 31, 2012
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	$ 988				$ 985
Net Expected Loss to be Paid After Recoveries for R&W	984	[1]	487		982	[1]	677
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	13		(88)
Net Expected Loss Development After Recoveries for R&W	12		(98)
Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	708				741
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(23)		(72)
Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	108	[2]			60	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	47	[2]	(33)	[2]
Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	172				184
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(11)	[3]	17	[3]
Prime first lien
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	18				21
Net Expected Loss to be Paid After Recoveries for R&W	18	[1]	11		21	[1]	6
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(3)		6
Net Expected Loss Development After Recoveries for R&W	(3)		6
Prime first lien | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	3				3
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0		0
Prime first lien | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	0	[2]			0	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[2]	0	[2]
Prime first lien | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	15				18
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(3)	[3]	6	[3]
Alt-A first lien
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	308				304
Net Expected Loss to be Paid After Recoveries for R&W	308	[1]	313		304	[1]	315
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	8		9
Net Expected Loss Development After Recoveries for R&W	8		9
Alt-A first lien | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	212				199
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	19		5
Alt-A first lien | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	19	[2]			31	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(12)	[2]	(1)	[2]
Alt-A first lien | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	77				74
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	1	[3]	5	[3]
Option ARM
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	(28)				(9)
Net Expected Loss to be Paid After Recoveries for R&W	(28)	[1]	(327)		(9)	[1]	(131)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(15)		(138)
Net Expected Loss Development After Recoveries for R&W	(15)		(138)
Option ARM | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	(38)				(18)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(16)		(93)
Option ARM | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	0	[2]			(2)	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	1	[2]	(37)	[2]
Option ARM | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	10				11
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[3]	(8)	[3]
First mortgage, subprime
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	295				304
Net Expected Loss to be Paid After Recoveries for R&W	295	[1]	263		304	[1]	242
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(7)		25
Net Expected Loss Development After Recoveries for R&W	(7)		25
First mortgage, subprime | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	140				149
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(8)		12
First mortgage, subprime | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	80	[2]			81	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(2)	[2]	4	[2]
First mortgage, subprime | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	75				74
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	3	[3]	9	[3]
Total first lien
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	593				620
Net Expected Loss to be Paid After Recoveries for R&W	593	[1]	260		620	[1]	432
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(17)		(98)
Net Expected Loss Development After Recoveries for R&W	(17)		(98)
Total first lien | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	317				333
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(5)		(76)
Total first lien | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	99	[2]			110	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(13)	[2]	(34)	[2]
Total first lien | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	177				177
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	1	[3]	12	[3]
Close ended second lien
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	(4)				(11)
Net Expected Loss to be Paid After Recoveries for R&W	(4)	[1]	(21)		(11)	[1]	(39)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	5		1
Net Expected Loss Development After Recoveries for R&W	5		1
Close ended second lien | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	(32)				(34)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(1)		5
Close ended second lien | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	26	[2]			25	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	2	[2]	(3)	[2]
Close ended second lien | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	2				(2)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	4	[3]	(1)	[3]
HELOCs
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	(109)				(116)
Net Expected Loss to be Paid After Recoveries for R&W	(109)	[1]	(122)		(116)	[1]	(111)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	2		(3)
Net Expected Loss Development After Recoveries for R&W	2		(3)
HELOCs | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	(92)				(41)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(56)		(7)
HELOCs | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	(17)	[2]			(75)	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	58	[2]	4	[2]
HELOCs | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	0				0
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[3]	0	[3]
Second lien
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	(113)				(127)
Net Expected Loss to be Paid After Recoveries for R&W	(113)	[1]	(143)		(127)	[1]	(150)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	7		(2)
Net Expected Loss Development After Recoveries for R&W	7		(2)
Second lien | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	(124)				(75)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(57)		(2)
Second lien | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	9	[2]			(50)	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	60	[2]	1	[2]
Second lien | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	2				(2)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	4	[3]	(1)	[3]
U.S. RMBS
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	480				493
Net Expected Loss to be Paid After Recoveries for R&W	480	[1]	117		493	[1]	282
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(10)		(100)
Net Expected Loss Development After Recoveries for R&W	(10)		(100)
U.S. RMBS | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	193				258
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(62)		(78)
U.S. RMBS | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	108	[2]			60	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	47	[2]	(33)	[2]
U.S. RMBS | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	179				175
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	5	[3]	11	[3]
TruPS
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	32				51
Net Expected Loss to be Paid After Recoveries for R&W	32	[1]	23		51	[1]	27
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(19)		(3)
Net Expected Loss Development After Recoveries for R&W	(19)		(3)
TruPS | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	2				3
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(1)		0
TruPS | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	0	[2]			0	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[2]	0	[2]
TruPS | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	30				48
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	(18)	[3]	(3)	[3]
Structured finance
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	138				120
Net Expected Loss to be Paid After Recoveries for R&W	138	[1]	307		120	[1]	312
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	19		(2)
Net Expected Loss Development After Recoveries for R&W	19		(2)
Structured finance | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	176				161
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	17		(10)
Structured finance | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	0	[2]			0	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[2]	0	[2]
Structured finance | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	(38)				(41)
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	2	[3]	8	[3]
Public Finance U.S.
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	281				264
Net Expected Loss to be Paid After Recoveries for R&W	281	[1]	(9)		264	[1]	7
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	23		7
Net Expected Loss Development After Recoveries for R&W	23		7
Public Finance U.S. | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	281				264
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	23		7
Public Finance U.S. | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	0	[2]			0	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[2]	0	[2]
Public Finance U.S. | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	0				0
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[3]	0	[3]
Public Finance Non-U.S.
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	57				57
Net Expected Loss to be Paid After Recoveries for R&W	57	[1]	62		57	[1]	52
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0		10
Net Expected Loss Development After Recoveries for R&W	0		10
Public Finance Non-U.S. | Financial guaranty insurance
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	56				55
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0		9
Public Finance Non-U.S. | Financial Guaranty Variable Interest Entities
Guarantor Obligations [Line Items]
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability	0	[2]			0	[2]
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[2]	0	[2]
Public Finance Non-U.S. | Credit Derivatives
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W Excluding Other Lines of Business	1				2
Net Expected Loss Development After Recoveries for R&W Excluding Other Lines of Business	0	[3]	1	[3]
Other
Guarantor Obligations [Line Items]
Net Expected Loss to be Paid After Recoveries for R&W	(4)				(3)
Net Expected Loss Development After Recoveries for R&W	$ (1)		$ (10)

[1] Includes expected loss adjustment expenses ("LAE") to be paid for mitigating claim liabilities of $29 million as of March 31, 2014 and $34 million as of December 31, 2013. The Company paid $6 million and $13 million in LAE for First Quarter 2014 and 2013, respectively.

[2] Refer to Note 9, Consolidated Variable Interest Entities.

[3] Refer to Note 8, Financial Guaranty Contracts Accounted for as Credit Derivatives.