Expected Losses to be Paid (Details 7) (USD $)	6 Months Ended				3 Months Ended				6 Months Ended						3 Months Ended				6 Months Ended						3 Months Ended				6 Months Ended						3 Months Ended				6 Months Ended						3 Months Ended				6 Months Ended						3 Months Ended				6 Months Ended								3 Months Ended				6 Months Ended				3 Months Ended				6 Months Ended																3 Months Ended			6 Months Ended
	Jun. 30, 2013 risk		Dec. 31, 2012 risk		Jun. 30, 2013 Prime first lien risk		Jun. 30, 2012 Prime first lien		Jun. 30, 2013 Prime first lien risk		Jun. 30, 2012 Prime first lien		Dec. 31, 2012 Prime first lien risk		Jun. 30, 2013 Alt-A first lien risk		Jun. 30, 2012 Alt-A first lien		Jun. 30, 2013 Alt-A first lien risk		Jun. 30, 2012 Alt-A first lien		Dec. 31, 2012 Alt-A first lien risk		Jun. 30, 2013 First mortgage, option adjustable rate mortgage risk		Jun. 30, 2012 First mortgage, option adjustable rate mortgage		Jun. 30, 2013 First mortgage, option adjustable rate mortgage risk		Jun. 30, 2012 First mortgage, option adjustable rate mortgage		Dec. 31, 2012 First mortgage, option adjustable rate mortgage risk		Jun. 30, 2013 First mortgage, subprime risk		Jun. 30, 2012 First mortgage, subprime		Jun. 30, 2013 First mortgage, subprime risk		Jun. 30, 2012 First mortgage, subprime		Dec. 31, 2012 First mortgage, subprime risk		Jun. 30, 2013 Closed end second lien and HELOCs risk		Jun. 30, 2012 Closed end second lien and HELOCs		Jun. 30, 2013 Closed end second lien and HELOCs risk		Jun. 30, 2012 Closed end second lien and HELOCs		Dec. 31, 2012 Closed end second lien and HELOCs risk		Jun. 30, 2013 HELOCs risk		Jun. 30, 2012 HELOCs		Jun. 30, 2013 HELOCs risk		Jun. 30, 2012 HELOCs		Dec. 31, 2012 HELOCs risk		Jun. 30, 2013 RMBS loan_file		Jun. 30, 2013 Second lien		Jun. 30, 2012 Second lien		Jun. 30, 2013 Second lien		Jun. 30, 2012 Second lien		Jun. 30, 2013 Total first lien		Jun. 30, 2012 Total first lien		Jun. 30, 2013 Total first lien		Jun. 30, 2012 Total first lien		Jun. 30, 2013 Bank of America Agreement	Apr. 14, 2011 Bank of America Agreement	Jun. 30, 2013 Bank of America Agreement Second lien	Jun. 30, 2013 Bank of America Agreement Total first lien	Jun. 30, 2013 Deutsche Bank Agreement	May 08, 2012 Deutsche Bank Agreement Transaction	May 08, 2012 Deutsche Bank Agreement Covered Transactions	May 08, 2012 Deutsche Bank Agreement Uninsured tranches of covered transactions	Jun. 30, 2013 UBS		May 06, 2013 UBS	Jun. 30, 2013 Other	Jun. 30, 2013 Minimum	Jun. 30, 2013 Maximum	Jun. 30, 2013 Maximum Deutsche Bank Agreement Uninsured tranches of covered transactions	Jun. 30, 2013 Flagstar
Guarantor Obligations [Line Items]
Amount of Liabilities Agreed Paid by Entities Providing R and Ws for Transactions Company Provided a Financial Guaranty	$ 3,500,000,000
Cash Amount Already Received for Liabilities Agreed Paid by Entities Providing R and Ws for Transactions Company Provided a Financial Guaranty	2,300,000,000
Estimated Benefit From Loan Repurchases Related to Breaches of R and W Included in Net Expected Loss Estimates Under Agreements	600,000,000
Amount of Liabilities Agreed Paid by Entities Providing R and Ws for Transactions Company Provided a Financial Guaranty, Repurchase Amounts Prior to Settlement																																																																	600,000,000	[1]
Financial Guaranty Insurance Contracts Principal Amount	6,593,000,000																																																																																				1,621,000,000	1,246,000,000	2,162,000,000				979,000,000	[2]		585,000,000
Cash Amount Already Received for Liabilities Agreed Paid by Entities Providing R and Ws for Transactions Company Provided a Financial Guaranty	2,066,000,000																																																																																				968,000,000	406,000,000	173,000,000				347,000,000	[2]		172,000,000
Estimated Benefit From Loan Repurchases Related to Breaches of R and W Included in Net Expected Loss Estimates Under Agreements, Net of Reinsurance	614,000,000																																																																																					263,000,000	139,000,000				93,000,000	[2]		119,000,000
Assets held under trust for reimbursement payment	1,163,000,000																																																																																					665,000,000	271,000,000				227,000,000	[2],[3]
Estimated Benefit From Loan Repurchases Related to Breaches of R and W Included in Net Expected Loss Estimates in Pursuit	350,000,000
Estimated Period of Recoveries on Transactions Backed by Heloc and Closed End Second Lien Loans Not Subject to settlement Agreements																																																																																															2 years	4 years
R&W recovered during period	614,000,000				0	[4]	0	[4]	0	[5]	0	[5]			9,000,000	[4]	63,000,000	[4]	17,000,000	[5]	64,000,000	[5]			410,000,000	[4]	58,000,000	[4]	464,000,000	[5]	76,000,000	[5]			0	[4]	0	[4]	0	[5]	0	[5]			3,000,000	[4]	85,000,000	[4]	24,000,000	[5]	85,000,000	[5]			103,000,000	[4]	17,000,000	[4]	109,000,000	[5]	68,000,000	[5]					106,000,000	[4]	102,000,000	[4]	133,000,000	[5]	153,000,000	[5]	419,000,000	[4]	121,000,000	[4]	481,000,000	[5]	140,000,000	[5]
Estimated Benefit From Loan Repurchases Related to Breaches of R and W Included in Net Expected Loss Estimates	964,000,000
Loss Sharing Percentage																																																																																				80.00%									85.00%
Financial Guaranty Insurance Contracts Principal Amount Already Covered Under Agreements But Company Projects Receivinb Additional Amounts	1,607,000,000
Financial Guaranty Insurance Contracts Principal Amount Not Covered Under Agreements	2,108,000,000
Proceeds from legal settlements																																																																																																		105,000,000
Maximum Loss Up To Which Loss Sharing Percentage Applicable																																																																																				6,600,000,000
Collateral Losses																																																																																			3,500,000,000
Estimated Cumulative Collateral Losses																																																																																			5,100,000,000
Loss sharing percentage, first layer																																																																																									80.00%
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicatble																																																																																									319,000,000	141,000,000
Number of Transactions Settled Through Litigation																																																																																								3
Loss sharing percentage, second layer																																																																																										60.00%
Minimum losses at which second later of loss sharing percentage becomes applicable																																																																																										161,000,000
Minimum losses at which third layer of loss sharing percentage becomes applicable																																																																																										185,000,000
Loss sharing percentage, third layer																																																																																										100.00%
Maximum aggregate collateral losses up to which third layer of loss sharing will be applicable																																																																																										248,000,000
Losses Incurred by the Company																																																																																																	146,000,000
Number of Defaulted Loan Files Reviewed with Breached Representations and Warranties																																																																	23,500
Aggregate Loan Amount of Defaulted Loan Files Reviewed with Breached Representations and Warranties																																																																	6,500,000,000
Number of Risks as of the end of the period with R&W Benefit Recorded (in policies)	56	[6]	53	[6]	1	[6]			1	[6]			1	[6]	28	[6]			28	[6]			26	[6]	10	[6]			10	[6]			10	[6]	5	[6]			5	[6]			5	[6]	4	[6]			4	[6]			4	[6]	8	[6]			8	[6]			7	[6]
Outstanding Principal and Interest on Representations and Warranties Policies	$ 6,610,000,000		$ 7,198,000,000		$ 40,000,000				$ 40,000,000				$ 44,000,000		$ 3,904,000,000				$ 3,904,000,000				$ 4,173,000,000		$ 915,000,000				$ 915,000,000				$ 1,183,000,000		$ 965,000,000				$ 965,000,000				$ 989,000,000		$ 175,000,000				$ 175,000,000				$ 260,000,000		$ 611,000,000				$ 611,000,000				$ 549,000,000

[1] These amounts were paid into the relevant RMBS transactions prior to settlement and distributed in accordance with the priority of payments set out in the relevant transaction documents. Because the Company may insure only a portion of the capital structure of a transaction, such payments will not necessarily directly benefit the Company dollar-for-dollar, especially in first lien transactions.

[2] This table relates only to past and projected future recoveries under R&W and related agreements. Excluded is the $350 million of future net recoveries the Company projects receiving from R&W counterparties in transactions with $2,108 million of net par outstanding as of June 30, 2013 not covered by current agreements and $1,607 million of net par already covered by agreements but for which the Company projects receiving additional amounts.

[3] Eligible assets were first placed in trust in July 2013 so that amount is shown here.

[4] Gross amounts recovered were $543 million and $234 million for Second Quarter 2013 and 2012, respectively.

[5] Gross amounts recovered were $635 million and $311 million for Six Months 2013 and 2012, respectively.

[6] A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments. This table shows the full future Debt Service (not just the amount of Debt Service expected to be reimbursed) for risks with projected future R&W benefit, whether pursuant to an agreement or not.