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Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2012 | Dec. 31, 2011
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Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | $ 12,174 |  | $ 16,206
Fair value financial liabilities measured on recurring basis | 6,926 |  | 10,946
Variable Interest Entity [Member] | Loans Receivable [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,881 |  | 2,046
Variable Interest Entity [Member] | Loan Repurchase Commitments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,086 |  | 1,077
Cash And Cash Equivalents [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 814 |  | 473
Cash [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 176 |  | 160
State And Municipal Bonds [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 41 |  |
Corporate Obligations [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 293 |  | 239
Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 3
Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 875 |  | 1,458
Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 417 |  | 581
Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 340 |  | 533
Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 184 |  | 303
Money Market Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 593 |  | 912
Money Market Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 210 |  | 199
Equity Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 57 |  | 157
Medium-Term Notes [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 165 |  | 165
Fixed-Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 5,203 |  | 7,613
Fixed-Maturity Investments [Member] | U.S. Treasury And Government Agency [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 884 |  | 1,141
Fixed-Maturity Investments [Member] | State And Municipal Bonds [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,532 |  | 2,089
Fixed-Maturity Investments [Member] | Foreign Governments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 196 |  | 350
Fixed-Maturity Investments [Member] | Corporate Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,216 |  | 1,739
Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 988 |  | 1,276
Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 98 |  | 367
Fixed-Maturity Investments [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 48 |  | 66
Fixed-Maturity Investments [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 96 |  | 138
Fixed-Maturity Investments [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 145 |  | 447
Derivative Assets [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4 |  | 2
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 3
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4 |  | 94
Derivative Assets [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 447
Derivative Assets [Member] | Credit Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 1
Derivative Assets [Member] | Other [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | (93)
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 141 |  | 281
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | (2) |  | 445
Derivative Liabilities [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | 527
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 2,934 |  | 4,808
Derivative Liabilities [Member] | Currency Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 21 |  | 17
Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 2 |  | 4
Derivative Liabilities [Member] | Other [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | (93)
Other Liabilities [Member] | Warrants [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 6 |  | 38
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 3,659 |  | 4,754
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 2,678 |  | 3,085
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Cash And Cash Equivalents [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 814 |  | 473
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Cash [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 176 |  | 160
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Money Market Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 585 |  | 912
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Money Market Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 210 |  | 199
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Equity Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 23 |  | 25
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 870 |  | 1,316
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] | U.S. Treasury And Government Agency [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 784 |  | 1,038
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] | Foreign Governments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 86 |  | 277
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 1
Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 6,049 |  | 8,576
Fair value financial liabilities measured on recurring basis | 2,175 |  | 2,651
Significant Other Observable Inputs (Level 2) [Member] | State And Municipal Bonds [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 41 |  |
Significant Other Observable Inputs (Level 2) [Member] | Corporate Obligations [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 215 |  | 170
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 3
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 869 |  | 1,437
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 410 |  | 559
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 215 |  | 330
Significant Other Observable Inputs (Level 2) [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 120 |  | 236
Significant Other Observable Inputs (Level 2) [Member] | Money Market Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 8 |  |
Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 20 |  | 121
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4,062 |  | 5,625
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | U.S. Treasury And Government Agency [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 100 |  | 103
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | State And Municipal Bonds [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,429 |  | 2,061
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Foreign Governments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 107 |  | 62
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,140 |  | 1,531
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 988 |  | 1,276
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 94 |  | 350
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 20 |  | 34
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 65 |  | 78
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 119 |  | 130
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 89 |  | 92
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 3
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 89 |  | 91
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] | Credit Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 1
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 141 |  | 281
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 287 |  | 445
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 13 |  | 18
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 1 |  | 4
Significant Other Observable Inputs (Level 2) [Member] | Other Liabilities [Member] | Warrants [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 6 |  | 38
Significant Other Observable Inputs (Level 2) [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 1,727 |  | 1,865
Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 3,537 |  | 4,638
Fair value financial liabilities measured on recurring basis | 5,044 |  | 8,388
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member] | Loans Receivable [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,881 |  | 2,046
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member] | Loan Repurchase Commitments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,086 |  | 1,077
Significant Unobservable Inputs (Level 3) [Member] | Corporate Obligations [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 78 | [1] | 69
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 6 | [1] | 21
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 7 | [1] | 22
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 125 | [1] | 203
Significant Unobservable Inputs (Level 3) [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 64 | [1] | 67
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 14 | [1] | 11
Significant Unobservable Inputs (Level 3) [Member] | Medium-Term Notes [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 165 | [1] | 165
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 271 |  | 672
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | State And Municipal Bonds [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 103 | [1] | 28
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Foreign Governments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 3 | [1] | 11
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 76 | [1] | 207
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4 | [1] | 17
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 28 | [1] | 32
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 31 | [1] | 60
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 26 | [1] | 317
Significant Unobservable Inputs (Level 3) [Member] | Derivative Assets [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 5 |  | 3
Significant Unobservable Inputs (Level 3) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 5 | [1] | 3
Significant Unobservable Inputs (Level 3) [Member] | Derivative Assets [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 447
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 4 | [1] |
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | 527
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 2,921 |  | 4,790
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 21 | [1] | 17
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 1 | [1] |
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 1,932 |  | 2,889
Counterparty and Cash Collateral Netting [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (90) |  | (93)
Fair value financial liabilities measured on recurring basis | (293) |  | (93)
Counterparty and Cash Collateral Netting [Member] | Derivative Assets [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (90) |  | (93)
Counterparty and Cash Collateral Netting [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (90) |  |
Counterparty and Cash Collateral Netting [Member] | Derivative Assets [Member] | Other [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | (93)
Counterparty and Cash Collateral Netting [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | (293) |  |
Counterparty and Cash Collateral Netting [Member] | Derivative Liabilities [Member] | Other [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | $ (93)
[1] | Unobservable inputs are either not developed by the Company or do not significantly impact the overall fair values of the aggregate financial assets and liabilities.

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- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph a, f, g -Article 7 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph a -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 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e24584-111560 + Details
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