v3.26.1
Fair Value of Financial Instruments (Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets Measured At Fair Value On A Recurring Basis) (Detail) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Discounted Cash Flow [Member] | Loans Carried at Fair Value [Member] | Discount Rate [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets $ 18 [1] $ 17 [2]
Discounted Cash Flow Type Certificate [Member] | Equity Investments [Member] | Discount Rate EBITDA Multiple EBITDA Royalty Share [Member]    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, assets 34 [1] 33 [2]
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 $ 34 $ 34
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 3.00% [3] 3.00% [4]
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 3.00% [3] 3.00% [4]
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 3.00% [3] 3.00% [4]
[1] Ranges for discount rate, EBITDA multiple and EBITDA royalty share are not meaningful.
[2] Ranges for discount rate, EBITDA multiples, EBITDA royalty share are not meaningful.
[3] Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value. The percentage is negative when the guarantees are in a net receivable position and positive when they are in a net payable position.
[4] Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value. The percentage is negative when the guarantees are in a net receivable position and positive when they are in a net payable position.