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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, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
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 | $ 16 | $ 6 | $ 29 | $ 45
Realized gains | 0 | 0 | 0 | 4
Realized Losses | (1) | 0 | (2) | (7)
Interest and dividend income | $ 3 | $ 4 | $ 8 | $ 18

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