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Investments - Net appreciation (decline) recognized in net income (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Realized capital gains and losses by asset type |  |  |  |
Net appreciation (decline) recognized in net income | $ 312 | $ 156 | $ 136 | $ 845
Equity securities |  |  |  |
Realized capital gains and losses by asset type |  |  |  |
Net appreciation (decline) recognized in net income | 184 | 107 | 116 | 736
Limited partnership interests |  |  |  |
Realized capital gains and losses by asset type |  |  |  |
Net appreciation (decline) recognized in net income | $ 128 | $ 49 | $ 20 | $ 109

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