v3.26.1
Fair Value Measurements (Summary Of Quantitative Information About Level 3 Fair Value Measurements) (Details)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2026
USD ($)
Dec. 31, 2025
USD ($)
Level 3 [Member] | Residential Mortgage    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Assets, Fair Value Disclosure $ 954 $ 970
Level 3 [Member] | Commercial Real Estate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Assets, Fair Value Disclosure   $ 93
Recurring Fair Value Measurements | Minimum [Member] | Discounted Cash Flow [Member] | Residential Mortgage    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Weighted Average CPR 0.043 0.042
Option-Adjusted Spread 4.70% 4.70%
Recurring Fair Value Measurements | Minimum [Member] | Discounted Cash Flow [Member] | Commercial Real Estate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Weighted Average CPR 0.069 0.065
Measurement Input, Discount Rate 8.00% 8.00%
Recurring Fair Value Measurements | Maximum [Member] | Discounted Cash Flow [Member] | Residential Mortgage    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Weighted Average CPR 0.153 0.169
Option-Adjusted Spread 8.00% 8.00%
Recurring Fair Value Measurements | Maximum [Member] | Discounted Cash Flow [Member] | Commercial Real Estate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Weighted Average CPR 0.076 0.076
Measurement Input, Discount Rate 10.00% 10.00%
Recurring Fair Value Measurements | Weighted Average [Member] | Discounted Cash Flow [Member] | Residential Mortgage    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Weighted Average CPR 0.075 0.075
Option-Adjusted Spread 5.00% 5.00%
Recurring Fair Value Measurements | Weighted Average [Member] | Discounted Cash Flow [Member] | Commercial Real Estate    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Weighted Average CPR 0.076 0.075
Measurement Input, Discount Rate 8.20% 8.20%