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Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) - Fair Value Measurements Recurring [Member] - USD ($) $ in Millions | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | $ 4,128 | $ 4,277
Fair value financial liabilities measured on recurring basis |  | 671 | 690
Counterparty and cash collateral netting |  | (3) |
Money Market Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 74 | 154
Medium-term Notes [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 96 | 108
Perpetual Debt And Equity Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 52 | 55
Cash and Cash Equivalents [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 446 | 75
Fixed Income Funds [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis | [1] | 47 | 51
Fixed Maturities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 2,756 | 3,202
Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 876 | 888
Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 192 | 200
Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 15 | 10
Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1,071 | 1,266
Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 266 | 330
Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 22 | 19
Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 25 | 22
Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 125 | 140
Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 164 | 327
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1 | 1
Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 524 | 486
Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 6 | 8
Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 40 | 45
Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 15 | 16
Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 8 | 6
Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 7 | 8
Assets Of Consolidated V I Es [Member] | Loans Receivable and other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 116 | 136
Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 14 | 8
Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 8 | 8
Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 14 | 18
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 10 | 9
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 186 | 132
Counterparty and cash collateral netting |  | (3) |
Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 37 | 34
Other Liabilities [Member] | Other Payable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | 4
Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 342 | 403
Fair Value Inputs Level 1 [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1,330 | 1,058
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Money Market Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 74 | 154
Fair Value Inputs Level 1 [Member] | Medium-term Notes [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Perpetual Debt And Equity Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 31 | 30
Fair Value Inputs Level 1 [Member] | Cash and Cash Equivalents [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 446 | 75
Fair Value Inputs Level 1 [Member] | Fixed Income Funds [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 771 | 791
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 771 | 791
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 |
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Loans Receivable and other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 8 | 8
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 1 [Member] | Other Liabilities [Member] | Other Payable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | 0
Fair Value Inputs Level 1 [Member] | Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 2,082 | 2,519
Fair value financial liabilities measured on recurring basis |  | 242 | 190
Fair Value Inputs Level 2 [Member] | Money Market Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Medium-term Notes [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Perpetual Debt And Equity Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 21 | 25
Fair Value Inputs Level 2 [Member] | Cash and Cash Equivalents [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Fixed Income Funds [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1,984 | 2,410
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 105 | 97
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 192 | 200
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 15 | 10
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1,071 | 1,266
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 266 | 330
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 22 | 19
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 25 | 22
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 125 | 140
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 163 | 326
Fair Value Inputs Level 2 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1 | 1
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 |
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 6 | 8
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 40 | 45
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 15 | 16
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 8 | 6
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 7 | 8
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Loans Receivable and other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  |  | 0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 2 | 2
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 189 | 132
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 2 [Member] | Other Liabilities [Member] | Other Payable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | 0
Fair Value Inputs Level 2 [Member] | Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 51 | 56
Fair Value Inputs Level 3 [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 669 | 649
Fair value financial liabilities measured on recurring basis |  | 432 | 500
Fair Value Inputs Level 3 [Member] | Money Market Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Medium-term Notes [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 96 | 108
Fair Value Inputs Level 3 [Member] | Perpetual Debt And Equity Securities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Cash and Cash Equivalents [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Income Funds [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1 | 1
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
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Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 1 | 1
Fair Value Inputs Level 3 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 524 | 486
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
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Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
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Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
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Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Loans Receivable and other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 116 | 136
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 14 | 8
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial assets measured on recurring basis |  | 14 | 18
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 8 | 7
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 0 | 0
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | 37 | 34
Fair Value Inputs Level 3 [Member] | Other Liabilities [Member] | Other Payable [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  |  | 4
Fair Value Inputs Level 3 [Member] | Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |
Fair value financial liabilities measured on recurring basis |  | $ 291 | $ 347
[1] | Investment that was measured at fair value by applying the net asset value per share practical expedient, and was required not to be classified in the fair value hierarchy.

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