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Fair Value Measurement (Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified | Jun. 30, 2012 | Mar. 31, 2012 | Dec. 31, 2011 | Jun. 30, 2011 | Mar. 31, 2011 | Dec. 31, 2010
--- | --- | --- | --- | --- | --- | ---
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, liabilities | $ 5,320 | $ 7,622 | $ 7,938 | $ 11,308 | $ 11,822 | $ 9,916
Fair Value | 3,544 | 3,937 | 4,188 | 4,528 | 4,439 | 4,467
Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value | 27 | 25 | 24 | 50 | 51 | 41
Recovery Rates [Member] | Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 23.00% |  |  |  |  |
Range, maximum | 90.00% |  |  |  |  |
Weighted Average | 51.00% |  |  |  |  |
Recovery Rates [Member] | Other Assets [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 42.00% |  |  |  |  |
Range, maximum | 75.00% |  |  |  |  |
Weighted Average | 47.00% |  |  |  |  |
Nonperformance Risk [Member] | Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 11.00% |  |  |  |  |
Range, maximum | 61.00% |  |  |  |  |
Weighted Average | 55.00% |  |  |  |  |
Nonperformance Risk [Member] | Multi-Sector CDO [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 61.00% |  |  |  |  |
Range, maximum | 61.00% |  |  |  |  |
Weighted Average | 61.00% |  |  |  |  |
Nonperformance Risk [Member] | Other Assets [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 11.00% |  |  |  |  |
Range, maximum | 61.00% |  |  |  |  |
Weighted Average | 42.00% |  |  |  |  |
Weighted Average Life [Member] | Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum(in years) | 0.5 |  |  |  |  |
Range, maximum(in years) | 6.1 |  |  |  |  |
Weighted Average(in years) | 4.9 |  |  |  |  |
Weighted Average Life [Member] | Other Assets [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum(in years) | 0.3 |  |  |  |  |
Range, maximum(in years) | 14.7 |  |  |  |  |
Weighted Average(in years) | 3.2 |  |  |  |  |
CMBS Spreads [Member] | Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum(in percentage) | 2.00% |  |  |  |  |
Range, maximum(in percentage) | 20.00% |  |  |  |  |
Weighted Average(in percentage) | 12.00% |  |  |  |  |
Variable Interest Entity [Member] | Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value | 12 | 15 | 22 | 27 | 29 | 23
Credit Derivatives [Member] | Commercial Mortgage-Backed [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Valuation Technique | BET Model |  |  |  |  |
Fair Value | 1,488 |  |  |  |  |
Credit Derivatives [Member] | Multi-Sector CDO [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Valuation Technique | Direct Price Model |  |  |  |  |
Fair Value | 691 |  |  |  |  |
Credit Derivatives [Member] | Other Assets [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Valuation Technique | BET Model |  |  |  |  |
Fair Value | 1,106 |  |  |  |  |
Loans Receivable [Member] | Variable Interest Entity [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Valuation Technique | Quoted market prices adjusted for financial guarantees provided to VIE obligations |  |  |  |  |
Fair Value | 1,903 | 2,025 | 2,046 | 2,320 | 2,327 | 2,183
Loans Receivable [Member] | Variable Interest Entity [Member] | Impact Of Financial Guarantee [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 0.00% |  |  |  |  |
Range, maximum | 111.00% |  |  |  |  |
Weighted Average | 6.00% |  |  |  |  |
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Valuation Technique | Discounted cash flow |  |  |  |  |
Fair Value | 1,032 | 1,076 | 1,077 | 905 | 867 | 835
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member] | Recovery Rates [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 9.00% |  |  |  |  |
Range, maximum | 96.00% |  |  |  |  |
Weighted Average | 42.00% |  |  |  |  |
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member] | Breach Rates [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 65.00% |  |  |  |  |
Range, maximum | 94.00% |  |  |  |  |
Weighted Average | 77.00% |  |  |  |  |
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Valuation Technique | Quoted market prices of VIE assets adjusted for financial guarantees provided |  |  |  |  |
Fair value, liabilities | $ 1,867 |  |  |  |  |
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] | Impact Of Financial Guarantee [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Range, minimum | 0.00% |  |  |  |  |
Range, maximum | 24.00% |  |  |  |  |
Weighted Average | 6.00% |  |  |  |  |

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- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -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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