Expected Loss to be Paid - Narrative (Details)			3 Months Ended			6 Months Ended			12 Months Ended
		Feb. 04, 2015 USD ($)	Jun. 30, 2016 USD ($) Transaction		Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Transaction Counterparty Curve Payment scenario		Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) scenario		Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jan. 15, 2013 USD ($)	Nov. 26, 2012 USD ($)	May 31, 2012 USD ($) Transaction
Schedule of Expected Losses to be Paid [Line Items]
Loss and LAE Reserve paid			$ 7,000,000		$ 5,000,000	$ 9,000,000		$ 9,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss			1,326,000,000	[1]	1,510,000,000	1,326,000,000	[1]	1,510,000,000	$ 1,391,000,000	[1]	$ 1,337,000,000	$ 1,154,000,000	$ 1,169,000,000
Economic loss development after recoveries for R&W			22,000,000		192,000,000	81,000,000		189,000,000
Net par amount outstanding			$ 329,864,000,000	[2]		$ 329,864,000,000	[2]		$ 358,571,000,000	[3]
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			25.00%			25.00%			10.00%		25.00%
Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Discount factor (as a percent)						2.46%			3.25%
Liquidation rate for bankruptcy delinquent category			100.00%			100.00%			100.00%		100.00%
Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			$ 5,054,000,000			$ 5,054,000,000			$ 5,053,000,000
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	[4]		(58,000,000)			$ (58,000,000)			79,000,000
Guarantor obligations, aggregate lifetime collateral losses, number of counterparties with collateralized by eligible assets held in trust | Counterparty						2
Liability for unpaid claims and claims adjustment expense, net largest single loss			192,000,000	[1]	524,000,000	$ 192,000,000	[1]	524,000,000	409,000,000	[1]	$ 293,000,000	570,000,000	584,000,000
Economic loss development after recoveries for R&W			(81,000,000)		(32,000,000)	(112,000,000)		(28,000,000)
Net par amount outstanding			$ 6,082,000,000			$ 6,082,000,000			$ 7,067,000,000
RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[5],[6]		15.00%			15.00%			15.00%		15.00%
RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[5],[6]		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	[5],[6]		15.00%			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	[7],[8]		10.00%			10.00%			10.00%		10.00%
RMBS [Member] | United States [Member] | Maximum [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	[7],[8]		15.40%			15.40%			15.00%		15.00%
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]
Net par amount outstanding			$ 3,255,000,000			$ 3,255,000,000			$ 4,379,000,000
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			3,000,000	[1]	106,000,000	3,000,000	[1]	106,000,000	20,000,000	[1]	$ 7,000,000	5,000,000	8,000,000
Economic loss development after recoveries for R&W			(3,000,000)		(3,000,000)	(2,000,000)		(15,000,000)
Net par amount outstanding			16,451,000,000			16,451,000,000			21,114,000,000
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			100,000,000	[1]	165,000,000	100,000,000	[1]	165,000,000	99,000,000	[1]	102,000,000	165,000,000	161,000,000
Economic loss development after recoveries for R&W			(2,000,000)		2,000,000	2,000,000		7,000,000
Net par amount outstanding			2,189,000,000			2,189,000,000			2,750,000,000
Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			31,000,000	[1]	58,000,000	31,000,000	[1]	58,000,000	54,000,000	[1]	32,000,000	62,000,000	68,000,000
Economic loss development after recoveries for R&W			(1,000,000)		1,000,000	(15,000,000)		(5,000,000)
Net par amount outstanding			1,645,000,000			1,645,000,000			1,818,000,000
Other Structured Finance and TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			3,000,000			3,000,000
Economic loss development after recoveries for R&W			(3,000,000)			(2,000,000)
Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			1,000,000,000	[1]	657,000,000	1,000,000,000	[1]	657,000,000	809,000,000	[1]	903,000,000	352,000,000	348,000,000
Economic loss development after recoveries for R&W			109,000,000		224,000,000	208,000,000		230,000,000
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			963,000,000	[1]	613,000,000	963,000,000	[1]	613,000,000	771,000,000	[1]	864,000,000	310,000,000	303,000,000
Economic loss development after recoveries for R&W			111,000,000		226,000,000	209,000,000		235,000,000
Net par amount outstanding			272,114,000,000	[2],[9]		272,114,000,000	[2],[9]		291,866,000,000	[3]
Public Finance Stockton Pension Oblgiation Bonds [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			115,000,000			115,000,000
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			366,000,000			366,000,000
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			80,000,000			80,000,000
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			34,000,000			34,000,000
Economic loss development after recoveries for R&W			(2,000,000)			(1,000,000)
Guarantor Obligations, Group One [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Number of claims agreed on to be reimbursed | Transaction																8
BIG [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			14,790,000,000			14,790,000,000			15,183,000,000
BIG [Member] | Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			5,100,000,000			5,100,000,000
BIG [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			3,427,000,000			3,427,000,000			3,973,000,000
BIG [Member] | Trust Preferred Securities (TruPS) [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			563,000,000			563,000,000			806,000,000
BIG [Member] | Other structured finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			828,000,000			828,000,000			863,000,000
BIG [Member] | Triple-X Life Insurance Transaction [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			$ 216,000,000			$ 216,000,000			216,000,000
Insured financial obligations, transactions related BIG | Transaction			2			2
BIG [Member] | Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			$ 110,000,000			$ 110,000,000			163,000,000
BIG [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			8,268,000,000	[9]		8,268,000,000	[9]		7,784,000,000
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			265,000,000			265,000,000
BIG [Member] | Parkway East [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			$ 20,000,000			$ 20,000,000
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	[4]		$ (90,000,000)			$ (90,000,000)			0
Liability for unpaid claims and claims adjustment expense, net largest single loss			78,000,000	[1]	521,000,000	78,000,000	[1]	521,000,000	348,000,000	[1]	228,000,000	569,000,000	595,000,000
Economic loss development after recoveries for R&W			(74,000,000)		(26,000,000)	(110,000,000)		(28,000,000)
First Lien [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			227,000,000	[1]	273,000,000	227,000,000	[1]	273,000,000	251,000,000	[1]	240,000,000	293,000,000	303,000,000
Economic loss development after recoveries for R&W			(26,000,000)		(6,000,000)	(25,000,000)		(7,000,000)
Net par amount outstanding			3,193,000,000			3,193,000,000			3,457,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			3,000,000	[1]	1,000,000	3,000,000	[1]	1,000,000	(2,000,000)	[1]	(1,000,000)	3,000,000	4,000,000
Economic loss development after recoveries for R&W			0		(1,000,000)	0		(1,000,000)
Net par amount outstanding			237,000,000			237,000,000			445,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			(56,000,000)	[1]	(18,000,000)	(56,000,000)	[1]	(18,000,000)	(28,000,000)	[1]	(47,000,000)	(16,000,000)	(16,000,000)
Economic loss development after recoveries for R&W			(10,000,000)		(3,000,000)	(31,000,000)		1,000,000
Net par amount outstanding			186,000,000			186,000,000			252,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss			(96,000,000)	[1]	265,000,000	(96,000,000)	[1]	265,000,000	127,000,000	[1]	$ 36,000,000	289,000,000	304,000,000
Economic loss development after recoveries for R&W			(38,000,000)		(16,000,000)	(54,000,000)		(21,000,000)
Net par amount outstanding			$ 1,090,000,000			$ 1,090,000,000			1,353,000,000
First Lien [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR			15.00%			15.00%
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%
Default from delinquentor rate, term						36 months
Guarantor obligations, default period currently performing						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						7 years
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] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net						$ 43,000,000
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						$ 100,000
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						$ 7,000,000
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						$ 13,000,000
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] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net						$ 59,000,000
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						400,000
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						14,000,000
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						33,000,000
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						(10,000,000)
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						(17,000)
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						(21,000,000)
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						$ (6,000,000)
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] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net						$ (35,000,000)
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						(100,000)
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						(32,000,000)
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						$ (18,000,000)
First 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%			80.00%
Maximum loss up to which loss sharing percentage applicable			$ 6,600,000,000			$ 6,600,000,000
Collateral losses			4,500,000,000			4,500,000,000
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			5,200,000,000			5,200,000,000
Assets held under trust for reimbursement payment			$ 577,000,000			$ 577,000,000
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%			85.00%
Guarantor obligations, number of future losses transactions reimbursed | Transaction						3
Assets held under trust for reimbursement payment			$ 44,000,000			$ 44,000,000
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			1,220,000,000			1,220,000,000			1,304,000,000
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			124,000,000			124,000,000			284,000,000
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			96,000,000			96,000,000			141,000,000
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			$ 621,000,000			$ 621,000,000			$ 793,000,000
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
Number of scenarios weighted in estimating expected losses | scenario						5			5
Period of loan default estimate						6 months
Number of preceding months average liquidation rates used to estimate loan default rate						6 months
Monthly delinquency threshold						5 months
Projected loss assumptions, period of consistent conditional default rate						6 months
Stress period (in months)						34 months
Period of constant conditional default rate (in months)						1 month
Loss recovery assumption (as a percent)			2.00%			2.00%			2.00%		2.00%
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	[4]		$ 32,000,000			$ 32,000,000			$ 79,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss			114,000,000	[1]	3,000,000	114,000,000	[1]	3,000,000	61,000,000	[1]	$ 65,000,000	$ 1,000,000	$ (11,000,000)
Economic loss development after recoveries for R&W			(7,000,000)		(6,000,000)	(2,000,000)		0
Net par amount outstanding			$ 1,376,000,000			$ 1,376,000,000			$ 1,560,000,000
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%			15.00%		15.00%
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						$ 49,000,000
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						$ 30,000,000
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																$ 319,000,000
Loss sharing percentage, first layer																80.00%
Second Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			$ 1,366,000,000			1,366,000,000			$ 1,451,000,000
Southern District of Mississippi Vs Madison County, Mississippi [Member] | Parkway East [Member] | Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			20,000,000			$ 20,000,000
Payment time period on annual debt service						2 years
Healthcare [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			13,600,000,000			$ 13,600,000,000
Healthcare [Member] | BIG [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding			303,000,000			303,000,000
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [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	[10]		29,000,000			29,000,000			38,000,000
Economic loss development after recoveries for R&W	[11]		(9,000,000)		(6,000,000)	(13,000,000)		(13,000,000)
Financial Guarantee Accounted for as Credit Derivatives [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	[10]		(36,000,000)			(36,000,000)			(33,000,000)
Economic loss development after recoveries for R&W	[11]		(1,000,000)		(3,000,000)	(4,000,000)		(14,000,000)
Financial Guarantee Accounted for as Credit Derivatives [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	[10]		11,000,000			11,000,000			11,000,000
Economic loss development after recoveries for R&W	[11]		(1,000,000)		1,000,000	0		2,000,000
Financial Guarantee Accounted for as Credit Derivatives [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	[10]		0			0			0
Economic loss development after recoveries for R&W	[11]		0		0	0		0
Financial Guarantee Accounted for as Credit Derivatives [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	[10]		0			0			0
Economic loss development after recoveries for R&W	[11]		0		(6,000,000)	0		(6,000,000)
Financial Guarantee Accounted for as Credit Derivatives [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	[10]		0			0			0
Economic loss development after recoveries for R&W	[11]		0		(6,000,000)	0		(6,000,000)
Financial Guarantee Accounted for as Credit Derivatives [Member] | First Lien [Member] | RMBS [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	[10]		26,000,000			26,000,000			34,000,000
Economic loss development after recoveries for R&W	[11]		(9,000,000)		(7,000,000)	(13,000,000)		(13,000,000)
Financial Guarantee Accounted for as Credit Derivatives [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	[10]		32,000,000			32,000,000			39,000,000
Economic loss development after recoveries for R&W	[11]		(7,000,000)		(5,000,000)	(9,000,000)		(6,000,000)
Financial Guarantee Accounted for as Credit Derivatives [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	[10]		0			0			(4,000,000)
Economic loss development after recoveries for R&W	[11]		0		0	0		(1,000,000)
Financial Guarantee Accounted for as Credit Derivatives [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	[10]		(5,000,000)			(5,000,000)			(1,000,000)
Economic loss development after recoveries for R&W	[11]		(1,000,000)		1,000,000	(3,000,000)		4,000,000
Financial Guarantee Accounted for as Credit Derivatives [Member] | First Lien [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	[10]		(1,000,000)			(1,000,000)			0
Economic loss development after recoveries for R&W	[11]		(1,000,000)		(3,000,000)	(1,000,000)		(10,000,000)
Financial Guarantee Accounted for as Credit Derivatives [Member] | Second Lien [Member] | RMBS [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	[10]		3,000,000			3,000,000			$ 4,000,000
Economic loss development after recoveries for R&W	[11]		$ 0		$ 1,000,000	$ 0		$ 0
ACA 2005-2 Collateralized Debt Obligations [Member] | CIFG Holding Inc. [Member] | Credit Default Swap [Member] | Financial Guarantee Accounted for as Credit Derivatives [Member] | CIFG Holdings Inc. vs JP Morgan Securities LLC [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss															$ 400,000,000
Libertas II Collateralized Debt Obligations [Member] | CIFG Holding Inc. [Member] | Credit Default Swap [Member] | Financial Guarantee Accounted for as Credit Derivatives [Member] | CIFG Holdings Inc. vs JP Morgan Securities LLC [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss															$ 325,000,000
Class A-1 Note [Member] | Domestic Corporate Debt Securities [Member] | CIFG Holding Inc. [Member] | CIFG Holding Inc. vs Goldman, Sachs & Co [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss														$ 325,000,000
Class A-2 Note [Member] | Domestic Corporate Debt Securities [Member] | CIFG Holding Inc. [Member] | CIFG Holding Inc. vs Goldman, Sachs & Co [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Purchased debt securities														$ 10,000,000
Positive Outcome of Litigation [Member] | CIFG Holding Inc. [Member] | CIFG Holding Inc. vs Goldman, Sachs & Co [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Awarded damages		$ 2,500,000

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

[2] Excludes $1.4 billion of loss mitigation securities insured and held by the Company as of June 30, 2016, which are primarily BIG.

[3] Excludes $1.5 billion of loss mitigation securities insured and held by the Company as of December 31, 2015, which are primarily BIG.

[4] The Company’s agreements with R&W providers generally provide that, as the Company makes claim payments, the R&W providers reimburse it for those claims; if the Company later receives reimbursement through the transaction (for example, from excess spread), the Company repays the R&W providers. See the section “Breaches of Representations and Warranties” for information about the R&W agreements and eligible assets held in trust with respect to such agreements. When the Company projects receiving more reimbursements in the future than it projects paying in claims on transactions covered by R&W settlement agreements, the Company will have a net R&W payable.

[5] 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.

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

[7] 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.

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

[9] Subsequent to June 30, 2016, and as a result of its July 1, 2016 Puerto Rico claim payments, the Company downgraded from BIG 1 to BIG 3 $1,803 million net par outstanding of financial guaranty insurance across two risks..

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

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