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Loss And Loss Adjustment Expense Reserves (RMBS Reserves) (Narrative) (Detail) (USD $) | 1 Months Ended |  | 12 Months Ended |
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Nov. 30, 2012 | Dec. 31, 2012 | Dec. 31, 2012 December 2012 to May 2013 [Member] Scenario, Forecast [Member] | Dec. 31, 2012 December 2012 to May 2013 [Member] Linear reduction in original value [Member] Scenario, Forecast [Member] | Dec. 31, 2012 March 31, 2013 to June 30, 2014 [Member] | Dec. 31, 2012 RMBS And HELOC And CES [Member] | Dec. 31, 2012 RMBS And HELOC And CES [Member] December 2012 to May 2013 [Member] M | Dec. 31, 2012 RMBS And HELOC And CES [Member] December 2012 to May 2013 [Member] Scenario, Forecast [Member] M | Dec. 31, 2012 First-Lien RMBS Reserves [Member] D | Dec. 31, 2012 First-Lien RMBS Reserves [Member] Alt-A [Member] | Dec. 31, 2012 First-Lien RMBS Reserves [Member] Foreclosure [Member] | Dec. 31, 2012 First-Lien RMBS Reserves [Member] Real Estate Owned [Member] | Dec. 31, 2012 First-Lien RMBS Reserves [Member] Bankruptcy [Member]
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Charged-off loans recovery values |  | $ 0 |  |  |  |  |  |  |  |  |  |  |
Assumed roll rate for ninety plus day delinquent loans excluding foreclosures and Real Estate Owned |  |  |  |  |  | 95.00% |  |  |  |  |  |  |
Period of elevated delinquency and loss, beginning, months |  |  |  |  |  |  | 6 |  |  |  |  |  |
Percentage of loans in 30-59 days delinquent bucket | 10.00% |  |  |  |  |  |  |  |  |  |  |  |
Percentage of loans charged-off | 30.00% |  |  |  |  |  |  |  |  |  |  |  |
Percentage of Current Roll to Loss for the transaction | 3.00% |  |  |  |  |  |  |  |  |  |  |  |
Decrease in percentage of Current Roll to Loss for transaction |  |  | 25.00% | 0.75% |  |  |  |  |  |  |  |  |
Current Roll to Loss |  |  |  |  | 0.00% |  |  |  |  |  |  |  |
Period of elevated delinquency and loss for stress case, additional months |  |  |  |  |  |  |  | 6 |  |  |  |  |
Addition to case basis reserves before considering potential recoveries for elevated delinquency and loss for stress case |  |  |  |  |  | 110,000,000 |  |  |  |  |  |  |
Delinquency period charged off on transaction specific basis, days |  |  |  |  |  |  |  |  | 90 |  |  |  |
Assumed roll rate for loans |  |  |  |  |  |  |  |  |  |  | 90.00% | 90.00% | 75.00%
90+ day roll rate to loss set |  |  |  |  |  |  |  |  | 90.00% |  |  |  |
Percentage of loss after declining over a 24-month period |  |  |  |  |  |  |  |  |  | 25.00% |  |  |
Change in recoveries of actual and expected payments related to ineligible mortgages |  |  |  |  |  | $ 454,000,000 |  |  |  |  |  |  |

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- Definition Assumed roll rate for ninety plus day delinquent loans. + References No definition available. + Details
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- Details
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