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Loss And Loss Adjustment Expense Reserves (RMBS Recoveries) (Narrative) (Details) (USD $) | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2012 | Dec. 31, 2011 | Apr. 30, 2011 | Dec. 31, 2010
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Federal statutory rate | 35.00% | 35.00% |  |
Estimated insurance recoveries, after income taxes | $ 2,100,000,000 | $ 2,000,000,000 |  |
Percentage of recognized estimated recoveries in relationship to consolidated total shareholder's equity | 111.00% | 119.00% |  |
Percentage of ineligible mortgage loan recoveries of statutory capital | 112.00% | 89.00% |  |
Contract claims on ineligible mortgages | 4,800,000,000 |  |  |
Aggregate of estimated potential recoveries | 3,200,000,000 |  |  |
Settlement received for assured guaranty put-back claims |  |  | 1,100,000,000 |
Bank of America repurchase requests resolved |  |  |  | 8,000,000,000
Second-Lien RMBS Reserves [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Total estimated recoveries from ineligible loans | 3,200,000,000 |  |  |
Insurance loss recoverable | 2,100,000,000 |  |  |
Loan repurchase commitments | $ 1,100,000,000 |  |  |
First And Second Lien RMBS [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Percentage of ineligible mortgage loans | 80.00% |  |  |
RMBS And HELOC And CES [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Sum of probabilities assigned to all scenarios | 100.00% |  |  |
Current risk-free rate associated with underlying transaction, range, minimum | 1.00% |  |  |
Current risk-free rate associated with underlying transaction, range, maximum | 2.20% |  |  |

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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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- Definition The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I) -URI http://asc.fasb.org/extlink&oid=6889476&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 47 -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319 + Details
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