Fair Value Measurements (Summary Of Quantitative Information About Level 3 Fair Value Measurements) (Details) - Discounted Cash Flow [Member] - Residential Mortgage $ in Millions |
Sep. 30, 2024
USD ($)
|
Dec. 31, 2023
USD ($)
|
|---|---|---|
| Level 3 [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Assets, Fair Value Disclosure | $ 971 | $ 906 |
| Recurring Fair Value Measurements | Minimum [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Weighted Average CPR | 0.045 | 0.056 |
| Option-Adjusted Spread | 4.70% | 4.50% |
| Recurring Fair Value Measurements | Maximum [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Weighted Average CPR | 0.354 | 0.215 |
| Option-Adjusted Spread | 7.70% | 8.20% |
| Recurring Fair Value Measurements | Weighted Average [Member] | ||
| Fair Value Measurement Inputs and Valuation Techniques [Line Items] | ||
| Weighted Average CPR | 0.090 | 0.082 |
| Option-Adjusted Spread | 5.00% | 4.80% |