v3.24.2.u1
Fair Value of Financial Instruments (Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) - USD ($)
$ in Millions
Jun. 30, 2024
Dec. 31, 2023
Discounted Cash Flow Type Certificate [Member] | Equity Investments [Member] | Discount Rate EBITDA Multiple Initial Inventory Purchase Excess Factor EBITDA Royalty Share [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets [1] $ 45  
Discounted Cash Flow Sum of the Parts [Member] | Equity Investments [Member] | EBITDA MultiplesDiscount Rate Hard Asset Values Type Certificate Values Weightings [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets [2]   $ 108
Loans Receivable and Other Instruments at Fair Value [Member] | Discounted Cash Flow [Member] | Discount Rate [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets [1] 9  
Variable Interest Entity Primary Beneficiary [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Of VIE Assets Adjusted For Financial Guarantees Provided Or Market Prices Of Similar Liabilities [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair value, liabilities   78
Variable Interest Entity Primary Beneficiary [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets $ 31  
Variable Interest Entity Primary Beneficiary [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities or Internal Cash Flow Models Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets   $ 35
Variable Interest Entity Primary Beneficiary [Member] | Minimum [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Of VIE Assets Adjusted For Financial Guarantees Provided Or Market Prices Of Similar Liabilities [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [3]   74.00%
Variable Interest Entity Primary Beneficiary [Member] | Minimum [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [4] 27.00%  
Variable Interest Entity Primary Beneficiary [Member] | Minimum [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities or Internal Cash Flow Models Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [3]   27.00%
Variable Interest Entity Primary Beneficiary [Member] | Maximum [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Of VIE Assets Adjusted For Financial Guarantees Provided Or Market Prices Of Similar Liabilities [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [3]   74.00%
Variable Interest Entity Primary Beneficiary [Member] | Maximum [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [4] 27.00%  
Variable Interest Entity Primary Beneficiary [Member] | Maximum [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities or Internal Cash Flow Models Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [3]   27.00%
Variable Interest Entity Primary Beneficiary [Member] | Weighted Average [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Of VIE Assets Adjusted For Financial Guarantees Provided Or Market Prices Of Similar Liabilities [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [3]   74.00%
Variable Interest Entity Primary Beneficiary [Member] | Weighted Average [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [4] 27.00%  
Variable Interest Entity Primary Beneficiary [Member] | Weighted Average [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices of Similar Liabilities or Internal Cash Flow Models Adjusted for Financial Guarantees Provided to VIE Obligations [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Range percentage [3]   27.00%
[1] Ranges for discount rate, EBITDA multiple, initial inventory purchase excess factor and EBITDA royalty share are not meaningful.
[2] Ranges for EBITDA multiples, discount rate, weightings, hard asset values and type certificate values are not meaningful.
[3] Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value.
[4] Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value.