XML 49 R56.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified | Mar. 31, 2012 | Dec. 31, 2011
--- | --- | ---
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | $ 15,343 |  | $ 15,573
Fair value financial liabilities measured on recurring basis | 10,590 |  | 10,946
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 | 2,755 |  | 2,452
Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 8,270 |  | 8,576
Fair value financial liabilities measured on recurring basis | 2,587 |  | 2,651
Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4,394 |  | 4,638
Fair value financial liabilities measured on recurring basis | 8,079 |  | 8,388
Counterparty And Cash Collateral Netting [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (76) |  | (93)
Fair value financial liabilities measured on recurring basis | (76) |  | (93)
Perpetual Preferred Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 49 |  | 107
Perpetual Preferred Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 49 |  | 106
Perpetual Preferred Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 1
Money Market Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 953 |  | 912
Money Market Securities [Member] | 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 | 953 |  | 912
Medium-Term Notes [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 174 |  | 165
Medium-Term Notes [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 174 | [1] | 165
Total Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 8,046 |  | 8,682
Total Investments [Member] | 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 | 2,133 |  | 2,253
Total Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 5,481 |  | 5,746
Total Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 432 |  | 683
Fixed-Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 7,005 |  | 7,628
Fixed-Maturity Investments [Member] | 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 | 1,151 |  | 1,316
Fixed-Maturity Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 5,432 |  | 5,640
Fixed-Maturity Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 422 |  | 672
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 5,912 |  | 6,448
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | 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 | 1,151 |  | 1,316
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4,366 |  | 4,488
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 395 |  | 644
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | U.S. Treasury And Government Agency [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,085 |  | 1,141
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | U.S. Treasury And Government Agency [Member] | 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 | 888 |  | 1,038
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | U.S. Treasury And Government Agency [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 197 |  | 103
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Foreign Governments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 369 |  | 350
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Foreign Governments [Member] | 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 | 263 |  | 277
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Foreign Governments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 94 |  | 62
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Foreign Governments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 12 | [1] | 11
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Corporate Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,672 |  | 1,738
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Corporate Obligations [Member] | 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 |  |  | 1
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Corporate Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,487 |  | 1,531
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Corporate Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 185 | [1] | 206
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,210 |  | 1,284
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,201 |  | 1,276
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 9 |  | 8
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Non-Agency [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 233 |  | 367
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Non-Agency [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 219 |  | 350
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Non-Agency [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 14 | [1] | 17
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Commercial Mortgage-Backed [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 52 |  | 58
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Commercial Mortgage-Backed [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 27 |  | 34
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Mortgage-Backed Securities [Member] | Commercial Mortgage-Backed [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 25 | [1] | 24
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | Collateralized Debt Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 106 |  | 138
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | Collateralized Debt Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 71 |  | 78
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | Collateralized Debt Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 35 | [1] | 60
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | Other Asset-Backed [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 233 |  | 448
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | Other Asset-Backed [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 118 |  | 130
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | Other Asset-Backed [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 115 | [1] | 318
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | State And Municipal Bonds [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 952 |  | 924
Fixed-Maturity Investments [Member] | Taxable Bonds [Member] | Asset-Backed Securities [Member] | State And Municipal Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 952 |  | 924
Fixed-Maturity Investments [Member] | Tax-Exempt Bonds [Member] | State And Municipal Bonds [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,080 |  | 1,165
Fixed-Maturity Investments [Member] | Tax-Exempt Bonds [Member] | State And Municipal Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,053 |  | 1,137
Fixed-Maturity Investments [Member] | Tax-Exempt Bonds [Member] | State And Municipal Bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 27 | [1] | 28
Fixed-Maturity Investments [Member] | Tax-Exempt Bonds [Member] | Other-Fixed Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 13 |  | 15
Fixed-Maturity Investments [Member] | Tax-Exempt Bonds [Member] | Other-Fixed Maturity Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 13 |  | 15
Total Other Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 39 |  | 35
Total Other Investments [Member] | 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 | 29 |  | 25
Total Other Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 10 | [1] | 10
Derivative Assets [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 12 |  | 2
Derivative Assets [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 74 |  | 92
Derivative Assets [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 14 |  | 3
Derivative Assets [Member] | Counterparty And Cash Collateral Netting [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (76) |  | (93)
Derivative Assets [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 10 |  |
Derivative Assets [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 10 |  |
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] | Credit Derivatives [Member] | Non-Insured Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 1
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 | 78 |  | 94
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 74 |  | 91
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 4 | [1] | 3
Derivative Assets [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (76) |  | (93)
Derivative Assets [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] | Counterparty And Cash Collateral Netting [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | (76) |  | (93)
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 | 4,513 |  | 4,808
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 16 |  | 18
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 4,497 |  | 4,790
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 | 390 |  | 445
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 390 |  | 445
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 | 3 |  | 4
Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 3 |  | 4
Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | (76) |  | (93)
Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] | Counterparty And Cash Collateral Netting [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | (76) |  | (93)
Other Liabilities [Member] | Warrants [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 22 |  | 38
Other Liabilities [Member] | Warrants [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 22 |  | 38
Variable Interest Entity [Member] | Money Market Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 622 |  | 199
Variable Interest Entity [Member] | Money Market Securities [Member] | 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 | 622 |  | 199
Variable Interest Entity [Member] | Variable Interest Entity Notes [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 4,761 |  | 4,754
Variable Interest Entity [Member] | Variable Interest Entity Notes [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 1,897 |  | 1,865
Variable Interest Entity [Member] | Variable Interest Entity Notes [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 2,864 |  | 2,889
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 3,117 |  | 3,117
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 2,713 |  | 2,735
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 404 |  | 382
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 240 |  | 239
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 165 |  | 170
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 75 | [1] | 69
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 3 |  | 3
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 3 |  | 3
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Non-Agency [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,469 |  | 1,458
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Non-Agency [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,444 |  | 1,437
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Residential Mortgage-Backed Non-Agency [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 25 | [1] | 21
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Commercial Mortgage-Backed [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 574 |  | 581
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Commercial Mortgage-Backed [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 559 |  | 559
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Mortgage-Backed Securities [Member] | Commercial Mortgage-Backed [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 15 | [1] | 22
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Collateralized Debt Obligations [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 549 |  | 533
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Collateralized Debt Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 331 |  | 330
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Collateralized Debt Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 218 | [1] | 203
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Other Asset-Backed [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 282 |  | 303
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Other Asset-Backed [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 211 |  | 236
Variable Interest Entity [Member] | Fixed-Maturity Investments [Member] | Asset-Backed Securities [Member] | Other Asset-Backed [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 71 | [1] | 67
Variable Interest Entity [Member] | Derivative Assets [Member] | Credit Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 443 |  | 447
Variable Interest Entity [Member] | Derivative Assets [Member] | Credit Derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 443 | [1] | 447
Variable Interest Entity [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 2 |  | 3
Variable Interest Entity [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 2 |  | 3
Variable Interest Entity [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 525 |  | 527
Variable Interest Entity [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 525 | [1] | 527
Variable Interest Entity [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 259 |  | 281
Variable Interest Entity [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 259 |  | 281
Variable Interest Entity [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 19 |  | 17
Variable Interest Entity [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis | 19 | [1] | 17
Loans Receivable [Member] | Variable Interest Entity [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 2,025 |  | 2,046
Loans Receivable [Member] | Variable Interest Entity [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 2,025 |  | 2,046
Loan Repurchase Commitments [Member] | Assets Of Consolidated VIEs [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | 1,076 |  | 1,077
Loan Repurchase Commitments [Member] | Assets Of Consolidated VIEs [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | $ 1,076 |  | $ 1,077
[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.

X
- Definition Fair Value Liabilities Measured On Recurring Basis + References No definition available. + Details
Name: | mbi_FairValueLiabilitiesMeasuredOnRecurringBasis
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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 Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 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=6379932&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 FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 5: 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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 7 -Section 03 -Paragraph 1 -Subparagraph a, f, g 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=6956420&loc=d3e24584-111560 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant