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Loss And Loss Adjustment Expense Reserves (Loss And LAE Activity) (Narrative) (Detail) (USD $) | 12 Months Ended |  |  | 12 Months Ended |  |  |  |  | 12 Months Ended | 60 Months Ended |
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Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2012 Variable Interest Entity [Member] | Dec. 31, 2011 Variable Interest Entity [Member] | Dec. 31, 2012 RMBS And HELOC And CES [Member] | Dec. 31, 2012 Financial Guarantees [Member] | Dec. 31, 2012 Financial Guarantees [Member] Variable Interest Entity [Member] | Dec. 31, 2012 Loss And LAE Reserves [Member] | Dec. 31, 2011 Loss And LAE Reserves [Member] | Dec. 31, 2012 Second-Lien RMBS Reserves [Member] | Dec. 31, 2011 Second-Lien RMBS Reserves [Member] | Dec. 31, 2012 ABS CDO Portfolio [Member] | Dec. 31, 2012 ABS CDO Portfolio [Member] | Dec. 31, 2012 Classified [Member] RMBS And HELOC And CES [Member] Reviewed [Member] | Dec. 31, 2012 Classified [Member] Recoveries On Unpaid Losses [Member] RMBS And HELOC And CES [Member] Reviewed [Member] | Dec. 31, 2012 Insured Issues Designated As "Classified List" [Member] RMBS And HELOC And CES [Member]
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ABS CDO exposure decrease since December 31,2007 |  |  |  |  |  |  |  |  |  |  |  |  | 88.00% |  |  |
Aggregate ABS CDO Loss And LAE Reserves |  |  |  |  |  | $ 143,000,000 | $ 236,000,000 |  |  |  |  |  |  |  |  |
Policy holder (Benefits) and Claims Incurred | 50,000,000 |  |  |  |  |  |  |  |  |  |  | (21,000,000) |  |  |  |
Elimination of loss and LAE expense as result of consolidating VIE |  |  |  |  |  |  |  |  |  |  |  | 24,000,000 |  |  |  |
Reduction of excess interest cash flows |  |  |  |  | 83,000,000 |  |  |  |  |  |  |  |  |  |  |
Reserves for expected future claim payments |  |  |  |  |  |  |  | 1,200,000,000 | 1,400,000,000 |  |  |  |  |  |  |
Expected recoveries of future payments |  |  |  |  |  |  |  | 332,000,000 | 562,000,000 |  |  |  |  |  |  |
Paid losses and LAE, net of reinsurance and collections | 631,000,000 |  |  |  | 421,000,000 |  |  |  |  |  |  |  |  |  |  |
Increase in insurance loss recoverable related to paid losses | 602,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of insured issues reviewed |  |  |  |  |  |  |  |  |  |  |  |  |  | 29 |  | 34
Number of insured issues reviewed with recorded recoveries |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 26 |
Number of transactions received consideration and excluded from loan files reviewed with potential recoveries | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average risk-free rate used to discount claim liability | 1.38% | 1.53% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total estimated recoveries from ineligible loans |  |  |  |  |  |  |  |  |  | 3,600,000,000 | 3,100,000,000 |  |  |  |  |
Insurance Loss Recoverable from ineligible loans |  |  |  |  |  |  |  |  |  | 2,500,000,000 | 2,000,000,000 |  |  |  |  |
Loan repurchase commitments |  |  | $ 1,086,000,000 | $ 1,077,000,000 |  |  |  |  |  | $ 1,100,000,000 | $ 1,100,000,000 |  |  |  |  |

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- Definition Aggregate Asset Backed Securities Collateralized Debt Obligations Loss And Loss Adjustment Expense Reserves + References No definition available. + Details
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- Definition Asset Backed Securities Collateralized Debt Obligations Exposure Decrease + References No definition available. + Details
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- Definition Elimination Of Loss And LAE Expense As Result Of Consolidating VIEs + References No definition available. + Details
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- Definition Excess Interest Cash Flows From Securitizations + References No definition available. + Details
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- Definition Gross reserve, recoveries on unpaid losses + References No definition available. + Details
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- Definition Increase decrease in carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts related to recoveries related to commitments to recoveries on paid claims. + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of paid insurance policy claims and LAE expense expected to be recovered. + References No definition available. + Details
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- Definition The fair value of financial instruments that represent the right of the Trust against the seller/servicer for loans that were not compliant with the representations and warranties of the loan underwriting. The Trust has the right to demand that the transferor replace ineligible loans with a compliant loan or repurchase the non-compliant loan. + References No definition available. + Details
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- Details
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- Definition Losses And Loss Adjustment Expenses Net Of Reinsurance + References No definition available. + Details
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- Definition Number Of Insured Issues Reviewed With Recorded Recoveries + References No definition available. + Details
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- Definition Number Of Transactions Received Consideration And Excluded From Loan Files Reviewed With Potential Recoveries + References No definition available. + Details
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- Definition Reserves For Expected Future Claim Payments + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 17 -Article 5 + Details
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- Definition This element represents the weighted average risk free rate used to discount the claim liability related to financial guarantee insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 163 -Paragraph 30 -Subparagraph f(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Provision for benefits, claims and claims settlement expenses incurred during the period net of the effects of contracts assumed and ceded. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 5 -Article 7 + Details
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