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Investments - Narrative (Details) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2020 USD ($) | Dec. 31, 2020 USD ($) security | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Schedule of Investments [Line Items] |  |  |  |
Percentage (based on unrealized loss) of available for sale fixed maturities that are in unrealized loss position and rated investment grade |  | 76.00% |  |
Percentage (based on fair value) of available for sale fixed maturities that are in unrealized loss position and rated investment grade |  | 88.00% |  |
Net investment income |  | $ 2,132 | $ 2,303 | $ 2,094
Annuity |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Net investment income |  | 1,699 | 1,792 | 1,638
Neon Capital Limited |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Net investment income |  | (5) |  |
Neon Capital Limited | Accounting Standards Update 2016-01 | Equity securities |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Net investment income | $ (7) |  |  |
Residential MBS |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Fixed maturities, Available for sale, Gross Unrealized, Losses |  | $ (5) | (5) |
Number of securities purchased with credit deterioration | security |  | 2 |  |
Aggregate par value of securities purchased with credit deterioration, at time of purchase |  | $ 8 |  |
Aggregate purchase price of securities purchased with credit deterioration, at time of purchase |  | 6 |  |
Initial discount for purchased securities with credit deterioration |  | 1 |  |
Initial allowance for purchased securities with credit deterioration |  | 1 |  |
Fixed maturities |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Fixed maturities, Available for sale, Gross Unrealized, Losses |  | $ (118) | (88) |
Number of fixed maturities in an unrealized loss position | security |  | 620 |  |
Realized before impairments |  | $ 468 | 26 | 6
Fixed maturities | Annuity |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Realized before impairments |  | 415 |  |
Equity securities |  |  |  |
Schedule of Investments [Line Items] |  |  |  |
Realized before impairments |  | $ (96) | $ 277 | $ (265)

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