Debt Securities (Schedule Of Gross Gains And Gross Losses On Available For Sale Securities) (Details) - USD ($) $ in Millions |
12 Months Ended | ||||
|---|---|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
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| Investments, Debt and Equity Securities [Abstract] | |||||
| Gross realized gains | $ 16 | $ 4 | $ 22 | ||
| Gross realized losses | (43) | (1) | (5) | ||
| Other than Temporary Impairment | (1) | (2) | (1) | ||
| Available-for-sale Securities, Gross Realized Gain (Loss) | [1] | $ (28) | $ 1 | $ 16 | |
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