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Fair Value Measurements - Proceeds from the Sale of Investments (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Proceeds from the sale of investments in available-for-sale securities, realized gains and losses on those sales, and interest and dividend income |  |  |  |
Sale proceeds | $ 6 | $ 204 | $ 45 | $ 506
Realized gains | 0 | 8 | 4 | 20
Realized Losses | 0 | (7) | (7) | (18)
Interest and dividend income | $ 4 | $ 10 | $ 18 | $ 30

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