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Acquisitions Investments (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2021 | Dec. 31, 2019 | Oct. 07, 2021
Cigna's Life Insurance Business in Asia-Pacific Markets [Member] | Subsequent Event [Member] |  |  |  |
Investment Holdings [Line Items] |  |  |  |
BusinessAcquisitionCostOfAcquiredEntityExpectedCashConsideration [Member] |  |  |  | $ 5,750
Huatai Group [Member] | CHINA |  |  |  |
Investment Holdings [Line Items] |  |  |  |
Equity Method Investment, Ownership Percentage | 47.10% | 47.10% |  |
Equity method investment, additional 7.1 percentage agreed on |  |  | 7.10% |
Equity method investment, additional 6.4 percentage agreed on [Table] | 6.40% |  |  |
Equity method investment, incremental 0.9 percent obtained |  | 0.90% |  |
Purchase of incremental ownership interest |  | $ 65 |  |
Deposits Assets | $ 143 | $ 143 |  |

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