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Investments - Net appreciation (decline) recognized in net income (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Realized capital gains and losses by asset type |  |
Net appreciation (decline) recognized in net income | $ (615) | $ 463
Equity securities |  |
Realized capital gains and losses by asset type |  |
Net appreciation (decline) recognized in net income | (560) | 496
Limited partnership interests |  |
Realized capital gains and losses by asset type |  |
Net appreciation (decline) recognized in net income | $ (55) | $ (33)

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