Fair Value Measurements And Disclosure (Gain and Losses on Equity Securities) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2024 |
Sep. 30, 2023 |
Sep. 30, 2024 |
Sep. 30, 2023 |
|
| Fair Value Disclosures [Abstract] | ||||
| Total gains (losses) recognized on equity securities | $ 80 | $ (58) | $ 206 | $ 107 |
| Gains (losses) recognized on equity securities sold | 0 | (2) | (8) | (1) |
| Unrealized gains (losses) recognized on equity securities held at end of period | $ 80 | $ (56) | $ 214 | $ 108 |