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Acquisitions Acquisitions (narrative) (Details) - USD ($) $ in Millions |  | 6 Months Ended
--- | --- | ---
Jul. 13, 2020 | Jun. 30, 2020 | Jun. 30, 2019
Business Acquisition [Line Items] |  |  |
Payments for Other Deposits |  | $ 1,550 | $ 0
CHINA | Huatai Group [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Payments for Other Deposits |  | $ 1,550 |
CHINA | Huatai Group [Member] | Subsequent Event [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Equity method investment, additional 15.3 ownership percentage obtained | 15.30% |  |

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