Expected Loss to be Paid - Net Expected Loss to be Paid and Net Economic Loss Development by Accounting Model (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		$ 1,326	[1]	$ 1,510	$ 1,326	[1]	$ 1,510	$ 1,337	$ 1,391	[1]	$ 1,154	$ 1,169
Economic loss development after recoveries for R&W		22		192	81		189
Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		1,326			1,326				1,391
Economic loss development after recoveries for R&W		22		192	81		189
Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		1,000	[1]	657	1,000	[1]	657	903	809	[1]	352	348
Economic loss development after recoveries for R&W		109		224	208		230
Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		963	[1]	613	963	[1]	613	864	771	[1]	310	303
Economic loss development after recoveries for R&W		111		226	209		235
Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		37	[1]	44	37	[1]	44	39	38	[1]	42	45
Economic loss development after recoveries for R&W		(2)		(2)	(1)		(5)
RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		192	[1]	524	192	[1]	524	293	409	[1]	570	584
Economic loss development after recoveries for R&W		(81)		(32)	(112)		(28)
RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		78	[1]	521	78	[1]	521	228	348	[1]	569	595
Economic loss development after recoveries for R&W		(74)		(26)	(110)		(28)
RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		3	[1]	1	3	[1]	1	(1)	(2)	[1]	3	4
Economic loss development after recoveries for R&W		0		(1)	0		(1)
RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		(96)	[1]	265	(96)	[1]	265	36	127	[1]	289	304
Economic loss development after recoveries for R&W		(38)		(16)	(54)		(21)
RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		(56)	[1]	(18)	(56)	[1]	(18)	(47)	(28)	[1]	(16)	(16)
Economic loss development after recoveries for R&W		(10)		(3)	(31)		1
RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		227	[1]	273	227	[1]	273	240	251	[1]	293	303
Economic loss development after recoveries for R&W		(26)		(6)	(25)		(7)
RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		114	[1]	3	114	[1]	3	65	61	[1]	1	(11)
Economic loss development after recoveries for R&W		(7)		(6)	(2)		0
Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		100	[1]	165	100	[1]	165	102	99	[1]	165	161
Economic loss development after recoveries for R&W		(2)		2	2		7
Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		31	[1]	58	31	[1]	58	32	54	[1]	62	68
Economic loss development after recoveries for R&W		(1)		1	(15)		(5)
Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		3	[1]	106	3	[1]	106	7	20	[1]	5	8
Economic loss development after recoveries for R&W		(3)		(3)	(2)		(15)
Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		326	[1]	853	326	[1]	853	$ 434	582	[1]	$ 802	$ 821
Economic loss development after recoveries for R&W		(87)		(32)	(127)		(41)
Financial Guarantee Accounted for as Insurance Contracts [Member] | Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		1,208			1,208				1,239
Economic loss development after recoveries for R&W		40		207	101		219
Financial Guarantee Accounted for as Insurance Contracts [Member] | Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		1,000			1,000				809
Economic loss development after recoveries for R&W		109		230	208		236
Financial Guarantee Accounted for as Insurance Contracts [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		963			963				771
Economic loss development after recoveries for R&W		111		232	209		241
Financial Guarantee Accounted for as Insurance Contracts [Member] | Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		37			37				38
Economic loss development after recoveries for R&W		(2)		(2)	(1)		(5)
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		50			50				251
Economic loss development after recoveries for R&W		(66)		(24)	(97)		(16)
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		(18)			(18)				238
Economic loss development after recoveries for R&W		(65)		(17)	(98)		(17)
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		3			3				2
Economic loss development after recoveries for R&W		0		(1)	0		0
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		(115)			(115)				110
Economic loss development after recoveries for R&W		(39)		(12)	(56)		(10)
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		(51)			(51)				(27)
Economic loss development after recoveries for R&W		(9)		(4)	(28)		(3)
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		145			145				153
Economic loss development after recoveries for R&W		(17)		0	(14)		(4)
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		68			68				13
Economic loss development after recoveries for R&W		(1)		(7)	1		1
Financial Guarantee Accounted for as Insurance Contracts [Member] | Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		89			89				88
Economic loss development after recoveries for R&W		(1)		1	2		5
Financial Guarantee Accounted for as Insurance Contracts [Member] | Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		31			31				54
Economic loss development after recoveries for R&W		(1)		1	(15)		(5)
Financial Guarantee Accounted for as Insurance Contracts [Member] | Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		38			38				37
Economic loss development after recoveries for R&W		(1)		(1)	3		(1)
Financial Guarantee Accounted for as Insurance Contracts [Member] | Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W		208			208				430
Economic loss development after recoveries for R&W		(69)		(23)	(107)		(17)
Financial Guaranty Variable Interest Entities and Other [Member] | Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	114			114				136
Economic loss development after recoveries for R&W	[3]	(7)		(1)	(3)		1
Financial Guaranty Variable Interest Entities and Other [Member] | Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	113			113				120
Economic loss development after recoveries for R&W	[3]	(6)		(2)	(2)		1
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	70			70				76
Economic loss development after recoveries for R&W	[3]	0		(2)	1		2
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	20			20				17
Economic loss development after recoveries for R&W	[3]	2		(1)	3		(1)
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	50			50				59
Economic loss development after recoveries for R&W	[3]	(2)		(1)	(2)		3
Financial Guaranty Variable Interest Entities and Other [Member] | RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	43			43				44
Economic loss development after recoveries for R&W	[3]	(6)		0	(3)		(1)
Financial Guaranty Variable Interest Entities and Other [Member] | Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	0			0				0
Economic loss development after recoveries for R&W	[3]	0		0	0		0
Financial Guaranty Variable Interest Entities and Other [Member] | Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	1			1				16
Economic loss development after recoveries for R&W	[3]	(1)		1	(1)		0
Financial Guaranty Variable Interest Entities and Other [Member] | Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[2]	114			114				136
Economic loss development after recoveries for R&W	[3]	(7)		(1)	(3)		1
Financial Guarantee Accounted for as Credit Derivatives [Member] | Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	4			4				16
Economic loss development after recoveries for R&W	[5]	(11)		(14)	(17)		(31)
Financial Guarantee Accounted for as Credit Derivatives [Member] | Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	0			0				0
Economic loss development after recoveries for R&W	[5]	0		(6)	0		(6)
Financial Guarantee Accounted for as Credit Derivatives [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	0			0				0
Economic loss development after recoveries for R&W	[5]	0		(6)	0		(6)
Financial Guarantee Accounted for as Credit Derivatives [Member] | Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	0			0				0
Economic loss development after recoveries for R&W	[5]	0		0	0		0
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	29			29				38
Economic loss development after recoveries for R&W	[5]	(9)		(6)	(13)		(13)
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	26			26				34
Economic loss development after recoveries for R&W	[5]	(9)		(7)	(13)		(13)
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	0			0				(4)
Economic loss development after recoveries for R&W	[5]	0		0	0		(1)
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	(1)			(1)				0
Economic loss development after recoveries for R&W	[5]	(1)		(3)	(1)		(10)
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	(5)			(5)				(1)
Economic loss development after recoveries for R&W	[5]	(1)		1	(3)		4
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	32			32				39
Economic loss development after recoveries for R&W	[5]	(7)		(5)	(9)		(6)
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	3			3				4
Economic loss development after recoveries for R&W	[5]	0		1	0		0
Financial Guarantee Accounted for as Credit Derivatives [Member] | Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	11			11				11
Economic loss development after recoveries for R&W	[5]	(1)		1	0		2
Financial Guarantee Accounted for as Credit Derivatives [Member] | Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	0			0				0
Economic loss development after recoveries for R&W	[5]	0		0	0		0
Financial Guarantee Accounted for as Credit Derivatives [Member] | Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	(36)			(36)				(33)
Economic loss development after recoveries for R&W	[5]	(1)		(3)	(4)		(14)
Financial Guarantee Accounted for as Credit Derivatives [Member] | Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	[4]	4			4				$ 16
Economic loss development after recoveries for R&W	[5]	$ (11)		$ (8)	$ (17)		$ (25)

[1] Includes expected LAE to be paid of $8 million as of June 30, 2016 and $12 million as of December 31, 2015.

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

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

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

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