Expected Loss to be Paid - Narrative (Details) $ in Thousands		1 Months Ended		3 Months Ended			6 Months Ended				12 Months Ended
		Dec. 31, 2014 USD ($) risk Transaction		Jun. 30, 2015 USD ($) risk Transaction		Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) risk Transaction Curve Payment scenario		Jun. 30, 2014 USD ($)		Dec. 31, 2014 USD ($) risk Transaction		Apr. 01, 2015 USD ($)	Mar. 31, 2015 USD ($)	Sep. 12, 2014 Transaction	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Oct. 10, 2013 Transaction	May. 06, 2013	May. 08, 2012 USD ($)	Apr. 14, 2011 USD ($)
Schedule of Expected Losses to be Paid [Line Items]
Number of risks subject to R&W recovery | risk		29		30			30				29
Risks subject to R&W recovery, related net debt service amount		$ 2,100,000		$ 2,000,000			$ 2,000,000				$ 2,100,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		1,169,000	[1]	1,510,000	[1]	$ 1,035,000	1,510,000	[1]	$ 1,035,000		1,169,000	[1]		$ 1,154,000		$ 984,000	$ 982,000
Economic loss development after recoveries for R&W				192,000		23,000	$ 189,000		35,000
Number of transactions most sensitive to changes in losses in the future | Transaction							2
Net par amount outstanding		403,729,000	[2]	$ 390,384,000	[3],[4]		$ 390,384,000	[3],[4]			$ 403,729,000	[2]
Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Discount factor (as a percent)							0.00%				0.00%
Liquidation Rate for Bankruptcy Delinquent Category				10.00%			10.00%
Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Discount factor (as a percent)							3.37%				2.95%
Liquidation Rate for Bankruptcy Delinquent Category				100.00%			100.00%
Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		4,939,000		$ 5,430,000	[5],[6]		$ 5,430,000	[5],[6]			$ 4,939,000
Gross par outstanding		6,035,000		6,222,000			6,222,000				6,035,000
RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Amount of liabilities agreed to be paid by entities providing R&W for transaction in which the Company provided insurance				4,200,000			$ 4,200,000
RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum number of payments behind to be considered performing borrower | Payment							1
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		317,000		225,000	[7]	651,000	$ 225,000	[7]	651,000		317,000			245,000		721,000	712,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		584,000	[1]	524,000	[1]	476,000	524,000	[1]	476,000		584,000	[1]		$ 570,000		480,000	493,000
Economic loss development after recoveries for R&W				(32,000)		(59,000)	(28,000)		(69,000)
Net par amount outstanding		$ 9,417,000		$ 8,928,000			$ 8,928,000				$ 9,417,000
RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[8],[9]	15.00%		15.00%			15.00%				15.00%			15.00%
RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[8],[9]	15.00%		15.00%			15.00%				15.00%			15.00%
RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[8],[9]	15.00%									15.00%
RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[10],[11]	15.00%		15.00%			15.00%				15.00%			15.00%
RMBS [Member] | United States [Member] | Minimum [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[8],[9]			15.00%			15.00%							15.00%
RMBS [Member] | United States [Member] | Minimum [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[10],[11]	15.00%		10.00%			10.00%				15.00%			10.00%
RMBS [Member] | United States [Member] | Maximum [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[8],[9]			27.70%			27.70%							22.40%
RMBS [Member] | United States [Member] | Maximum [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[10],[11]	21.80%		15.00%			15.00%				21.80%			23.20%
HELOCs [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial period for which borrower can pay only interest payments							10 years
Trust Preferred Securities (TruPS) [Member]
Schedule of Expected Losses to be Paid [Line Items]
Percentage of installment premiums denominated in currencies other than the U.S. dollar							77.00%
Liability for unpaid claims and claims adjustment expense, net largest single loss		$ 23,000	[1]	$ 10,000	[1]	32,000	$ 10,000	[1]	32,000		$ 23,000	[1]		$ 14,000		32,000	51,000
Economic loss development after recoveries for R&W				(4,000)		0	(13,000)		(19,000)	[12]
Net par amount outstanding		4,326,000		4,850,000			4,850,000				4,326,000
Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss		161,000	[1]	165,000	[1]	87,000	165,000	[1]	87,000		161,000	[1]		165,000		87,000	75,000
Economic loss development after recoveries for R&W				2,000		1,000	7,000		14,000
Net par amount outstanding		3,133,000		3,133,000			3,133,000				3,133,000
Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss		68,000	[1]	58,000	[1]	58,000	58,000	[1]	58,000		68,000	[1]		62,000		54,000	52,000
Economic loss development after recoveries for R&W				1,000		4,000	(5,000)		6,000	[12]
Net par amount outstanding		1,857,000		1,827,000			1,827,000				1,857,000
Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss		(15,000)	[1]	96,000	[1]	(9,000)	96,000	[1]	(9,000)		(15,000)	[1]		(9,000)		(7,000)	(10,000)
Economic loss development after recoveries for R&W				1,000		0	(2,000)		3,000
Net par amount outstanding		31,514,000		27,145,000			27,145,000				31,514,000
Collateralized Loan Obligations [Member]
Schedule of Expected Losses to be Paid [Line Items]
Increase in net expected losses to be paid after R&W in pessimistic scenario							111,000
CMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Increase in net expected losses to be paid after R&W in pessimistic scenario							143,000
Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss		348,000	[1]	657,000	[1]	391,000	657,000	[1]	391,000		348,000	[1]		352,000		338,000	321,000
Economic loss development after recoveries for R&W				224,000		77,000	230,000		100,000
Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss		303,000	[1]	613,000	[1]	339,000	613,000	[1]	339,000		303,000	[1]		310,000		281,000	264,000
Economic loss development after recoveries for R&W				226,000		82,000	235,000		105,000
Net par amount outstanding		$ 322,123,000	[2]	312,182,000	[3],[4]		312,182,000	[3],[4]			$ 322,123,000	[2]
Public Finance [Member] | Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Economic loss development after recoveries for R&W				226,000			235,000
Net par amount outstanding				5,400,000			5,400,000
Public Finance Stockton General Fund [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				117,000			117,000
Cancelled lease revenue bonds				40,000			40,000
Non-Infrastructure Public Finance [Member] | Spain [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				383,000			383,000
Gross par outstanding				479,000			479,000
Non-Infrastructure Public Finance [Member] | Portugal [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				101,000			101,000
Gross par outstanding				108,000			108,000
Non-Infrastructure Public Finance [Member] | Hungary [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Gross par outstanding				475,000			475,000
Non-Infrastructure Public Finance [Member] | Spain, Hungry and Portugal [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss				41,000			41,000
Economic loss development after recoveries for R&W				2,000			4,000
Deutsche Bank [Member]
Schedule of Expected Losses to be Paid [Line Items]
Assets held under trust for reimbursement payment				$ 74,000			$ 74,000
Number of transactions terminated | Transaction		1									1				2			1
Number of transactions insured | Transaction				8			8
City of Detroit [Member] | Public Finance [Member] | United States [Member] | Unlimited Tax General Obligation [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				$ 18,000			$ 18,000
Guarantor obligation on un-exchanged balance, percent		15.50%
Louisville Arena Authority [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				337,000			337,000
BIG [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		$ 18,247,000		20,404,000	[4]		20,404,000	[4]			$ 18,247,000
BIG [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		5,643,000		5,393,000			5,393,000				5,643,000
BIG [Member] | Trust Preferred Securities (TruPS) [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		1,333,000		866,000			866,000				1,333,000
BIG [Member] | Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		598,000		598,000			598,000				598,000
BIG [Member] | Triple-X Life Insurance Transaction [Member] | Series A-1 Note [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				382,500			382,500
BIG [Member] | Triple-X Life Insurance Transaction [Member] | Series A-2 Note [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				40,500			40,500
BIG [Member] | Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		195,000		167,000			167,000				195,000
BIG [Member] | Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		1,224,000		1,872,000			1,872,000				1,224,000
BIG [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		7,850,000		9,897,000	[4]		9,897,000	[4]			7,850,000
BIG [Member] | Non-Infrastructure Public Finance [Member] | Hungary [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				466,000			466,000
BIG [Member] | Parkway East [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				21,000			21,000
Refinancing Risk on Infrastructure Transactions [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				$ 3,100,000			$ 3,100,000
Financial insurance guaranty, infrastructure finance, number of possible claims requiring payment, gross before reinsurance | Transaction				2			2
Financial insurance guaranty, infrastructure finance, possible claims requiring payment, gross before reinsurance				$ 1,900,000			$ 1,900,000
Refinancing Risk on Infrastructure Transactions [Member] | Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated years for recoveries of infrastructure transactions							10 years
Refinancing Risk on Infrastructure Transactions [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated years for recoveries of infrastructure transactions							35 years
First Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Number of delinquent payments | Payment							2
Projected loss assumptions, CDR, plateau rate, projection period							36 months
Projected loss assumptions, Final CDR, Period for voluntary prepayments to continue							12 months
Intermediate conditional default rate (as a percent)				5.00%			5.00%
Number of scenarios weighted in estimating expected losses | scenario							5
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		232,000		$ 142,000	[7]	509,000	$ 142,000	[7]	509,000		232,000			162,000		570,000	569,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		595,000	[1]	521,000	[1]	602,000	521,000	[1]	602,000		595,000	[1]		569,000		593,000	620,000
Economic loss development after recoveries for R&W				(26,000)		(21,000)	(28,000)		(38,000)
First Lien [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		15,000		(33,000)	[7]	144,000	(33,000)	[7]	144,000		15,000			(20,000)		152,000	173,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		(16,000)	[1]	(18,000)	[1]	(51,000)	(18,000)	[1]	(51,000)		(16,000)	[1]		(16,000)		(28,000)	(9,000)
Economic loss development after recoveries for R&W				(3,000)		(24,000)	1,000		(39,000)
Net par amount outstanding		407,000		338,000			338,000				407,000
First Lien [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		109,000		81,000	[7]	99,000	81,000	[7]	99,000		109,000			87,000		146,000	118,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		303,000	[1]	273,000	[1]	341,000	273,000	[1]	341,000		303,000	[1]		293,000		295,000	304,000
Economic loss development after recoveries for R&W				(6,000)		6,000	(7,000)		(1,000)
Net par amount outstanding		4,051,000		3,920,000			3,920,000				4,051,000
First Lien [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		2,000		1,000	[7]	3,000	1,000	[7]	3,000		2,000			1,000		3,000	4,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		4,000	[1]	1,000	[1]	11,000	1,000	[1]	11,000		4,000	[1]		3,000		18,000	21,000
Economic loss development after recoveries for R&W				(1,000)		(7,000)	(1,000)		(10,000)
Net par amount outstanding		471,000		498,000			498,000				471,000
First Lien [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		106,000		93,000	[7]	263,000	93,000	[7]	263,000		106,000			94,000		269,000	274,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		304,000	[1]	265,000	[1]	301,000	265,000	[1]	301,000		304,000	[1]		289,000		308,000	304,000
Economic loss development after recoveries for R&W				(16,000)		4,000	(21,000)		12,000
Net par amount outstanding		2,532,000		$ 2,397,000			$ 2,397,000				2,532,000
First Lien [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period							36 months
Period from plateau to intermediate conditional default rate (in months)							12 months
Period of constant intermediate conditional default rate (in months)							36 months
Intermediate conditional default rate as a percentage of plateau conditional default rate							20.00%
Final conditional default rate as a percentage of plateau conditional default rate							5.00%
Final conditional default rate, shortened term							3 months
Default from delinquentor rate, term							36 months
Projected loss assumptions, loss severity, subsequent period							18 months
Estimated loss severity rate, one through six months (as a percent)							18 months
Loss severity (as a percent)				40.00%			40.00%
Projected loss assumptions, period to reach final loss severity rate							2 years 6 months
Projected loss assumptions, Final CDR, Period for voluntary prepayments to continue							8 years
Current conditional prepayment rate used in alternate scenario for loss estimate (as a percent)				15.00%			15.00%
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period							42 months
Projected loss assumptions, period to reach final loss severity rate							4 years 6 months
Increase in the plateau period used to calculate potential change in loss estimate (in months)							6 months
Projected loss assumptions, prior period to reach final loss severity rate							2 years 6 months
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option Adjustable Rate Mortgage and Alt-A Mortgage [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss severity (as a percent)				45.00%			45.00%
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							$ 6,000
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							62,000
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							1,000
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							$ 25,000
First Lien [Member] | Somewhat Stressful Environment [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss severity (as a percent)				60.00%			60.00%
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period from plateau to intermediate conditional default rate (in months)							15 months
Projected loss assumptions, period to reach final loss severity rate							9 years
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							$ 14,000
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							87,000
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							4,000
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							69,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							13,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							10,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							41
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							$ (400)
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period							30 months
Period from plateau to intermediate conditional default rate (in months)							9 months
Decrease in the plateau period used to calculate potential change in loss estimate (in months)							6 months
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							$ (22,000)
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							(43,000)
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							(300)
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net							(24,000)
First Lien [Member] | Bank of America [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Collateral losses				$ 4,300,000			4,300,000
First Lien [Member] | Bank of America [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Collateral losses				5,200,000			5,200,000
First Lien [Member] | UBS [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Agreed reimbursement of R&W, percentage																			85.00%
Assets held under trust for reimbursement payment				79,000			79,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		183,000		160,000			160,000				183,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		1,575,000		1,557,000			1,557,000				1,575,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		353,000		336,000			336,000				353,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		1,841,000		1,750,000			$ 1,750,000				1,841,000
Second Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period from plateau to intermediate conditional default rate (in months)							28 months
Period of loan default estimate							5 months
Number of preceding months average liquidation rates used to estimate loan default rate							6 months
Projected loss assumptions, period of consistent conditional default rate							6 months
Stress period (in months)							34 months
Number of months of delinquent data							5 months
Period of constant conditional default rate (in months)							1 month
Conditional prepayment rate base case, average number of quarters							3 months
Number of conditional default rate curves modeled in estimating losses | Curve							5
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		85,000		83,000	[7]	142,000	$ 83,000	[7]	142,000		85,000			83,000		151,000	143,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		(11,000)	[1]	3,000	[1]	(126,000)	3,000	[1]	(126,000)		(11,000)	[1]		1,000		(113,000)	(127,000)
Economic loss development after recoveries for R&W				(6,000)		(38,000)	0		(31,000)
Second Lien [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		0		0	[7]	49,000	0	[7]	49,000		0			0		56,000	45,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		(19,000)	[1]	(6,000)	[1]	(117,000)	(6,000)	[1]	(117,000)		(19,000)	[1]		(10,000)		(109,000)	(116,000)
Economic loss development after recoveries for R&W				(3,000)		(33,000)	2,000		(31,000)
Net par amount outstanding		1,738,000		1,567,000			1,567,000				1,738,000
Second Lien [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates		85,000		83,000	[7]	93,000	83,000	[7]	93,000		85,000			83,000		95,000	98,000
Liability for unpaid claims and claims adjustment expense, net largest single loss		8,000	[1]	9,000	[1]	(9,000)	9,000	[1]	(9,000)		8,000	[1]		11,000		$ (4,000)	$ (11,000)
Economic loss development after recoveries for R&W				(3,000)		$ (5,000)	(2,000)		$ 0
Net par amount outstanding		$ 218,000		$ 208,000			$ 208,000				$ 218,000
Second Lien [Member] | RMBS [Member] | United States [Member] | Home Equity Line of Credit and Closed-end Mortgage [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR				15.00%			15.00%
Second Lien [Member] | HELOCs [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss recovery assumption (as a percent)		10.00%									10.00%
Second Lien [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period from plateau to intermediate conditional default rate (in months)							28 months
Stress period (in months)							34 months
Period of constant conditional default rate (in months)							6 months
Second Lien [Member] | Base Scenario One [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period							8 months
Period from plateau to intermediate conditional default rate (in months)							31 months
Stress period (in months)							39 months
Increase in conditional default rate ramp down period							3 months
Second Lien [Member] | Base Scenario One [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for increased conditional default rate plateau period							$ 38,000
Second Lien [Member] | Base Scenario One [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for decreased conditional default rate ramp down period							$ 1,000
Second Lien [Member] | Based Scenario Two [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Stress period (in months)							29 months
Period of constant conditional default rate (in months)							4 months
Change in estimate for decreased prepayment rate, Percent							10.00%
Decreased conditional default rate ramp down period							25 months
Second Lien [Member] | Based Scenario Two [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for decreased conditional default rate ramp down period							$ 38,000
Second Lien [Member] | Based Scenario Two [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for decreased conditional default rate ramp down period							1,000
Second Lien [Member] | Bank of America [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Agreed reimbursement of R&W, percentage																					80.00%
Maximum loss up to which loss sharing percentage applicable																					$ 6,600,000
Second Lien [Member] | Bank of America [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Assets held under trust for reimbursement payment				$ 557,000			557,000
Second Lien [Member] | Guarantor Obligations, Group One [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicable				319,000			319,000													$ 319,000
Loss sharing percentage, first layer																				80.00%
Second Lien [Member] | Guarantor Obligations, Group Two [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicable																				$ 389,000
Loss sharing percentage, first layer																				85.00%
Second Lien [Member] | Guarantor Obligations, Group Two [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicable																				$ 600,000
Second Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		$ 1,557,000		1,459,000			1,459,000				$ 1,557,000
Second Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding		$ 134,000		131,000			131,000				$ 134,000
Other Assets [Member]
Schedule of Expected Losses to be Paid [Line Items]
Office building, carrying value				30,000			30,000
Southern District of Mississippi Vs Madison County, Mississippi [Member] | Radian [Member] | Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				21,000			$ 21,000
Payment time period on annual debt service							2 years
Radian [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss														190,000
Net par amount outstanding	[3],[4]			13,100,000			$ 13,100,000
Radian [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														2,000
Liability for unpaid claims and claims adjustment expense, net largest single loss														4,000
Radian [Member] | Trust Preferred Securities (TruPS) [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss														0
Radian [Member] | Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss														0
Radian [Member] | Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss														0
Radian [Member] | Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss													$ 101,000	101,000
Radian [Member] | Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss														85,000
Radian [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss													$ 81,000	81,000
Radian [Member] | First Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														1,000
Liability for unpaid claims and claims adjustment expense, net largest single loss														3,000
Radian [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														0
Liability for unpaid claims and claims adjustment expense, net largest single loss														0
Radian [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														1,000
Liability for unpaid claims and claims adjustment expense, net largest single loss														(4,000)
Radian [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														0
Liability for unpaid claims and claims adjustment expense, net largest single loss														0
Radian [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														0
Liability for unpaid claims and claims adjustment expense, net largest single loss														7,000
Radian [Member] | Second Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														1,000
Liability for unpaid claims and claims adjustment expense, net largest single loss														1,000
Radian [Member] | Second Lien [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														0
Liability for unpaid claims and claims adjustment expense, net largest single loss														1,000
Radian [Member] | Second Lien [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates														1,000
Liability for unpaid claims and claims adjustment expense, net largest single loss														$ 0
Healthcare [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				15,900,000			15,900,000
Healthcare [Member] | BIG [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				376,000			376,000
Healthcare [Member] | Radian [Member] | BIG [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding				$ 325,000			$ 325,000
First Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, shortened period							3 months

[1] Includes expected LAE to be paid of $15 million as of June 30, 2015 and $16 million as of December 31, 2014.

[2] Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.

[3] Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of June 30, 2015, which are primarily in the BIG category.

[4] amounts include $13.1 billion of net par acquired from Radian Asset.

[5] In July 2015, various Puerto Rico issuers made payment on $293 million of par scheduled to be paid; of that amount, $74 million and $31 million of par was paid by PREPA and PRHTA, respectively.

[6] In Second Quarter 2015, the Company's Puerto Rico exposures increased due to (1) the Radian Asset Acquisition, which increased net par outstanding by $422 million, of which $22 million was for PREPA and $169 million for PRHTA, and (2) a commutation of previously ceded Puerto Rico exposures.

[7] See the section "Breaches of Representations and Warranties" below for eligible assets held in trust.

[8] For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.

[9] Represents variables for most heavily weighted scenario (the “base case”).

[10] For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.

[11] Represents variables for most heavily weighted scenario (the “base case”).

[12] Refer to Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.