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Acquisitions and Sale of Businesses - Narrative on sale of businesses (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Dec. 31, 2020 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Jun. 30, 2020
Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Proceeds from sale of businesses |  |  | $ 3,581 | $ 3 | $ 0 |
Realized gains on subsidiaries |  |  | 4 | 23 | 0 |
Income tax expense (benefit) |  |  | $ 254 | 25 | $ 143 |
Neon Capital Limited |  |  |  |  |  |
Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Proceeds from sale of businesses | $ 10 |  |  | $ 6 |  |
Carrying value of assets and liabilities disposed, percentage of total assets and liabilities |  | 1.00% |  | 1.00% |  |
Realized gains on subsidiaries | $ 4 | $ 23 |  | $ 23 |  |
Income tax expense (benefit) |  |  |  | $ (72) |  |
Neon Capital Limited Executives | Neon Capital Limited |  |  |  |  |  |
Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Percent of noncontrolling interest acquired from former and current Neon executives |  |  |  |  |  | 100.00%

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