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Equity (Aggregate Share Repurchases) (Details) - USD ($) shares in Millions, $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items] |  |  |
Cash consideration | $ 504 | $ 5,320 | $ 5,435
New Authorization [Member] |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |
Cash consideration | $ 0 | $ 5,000 | $ 5,000
Shares repurchased (in shares) | 0 | 140 | 131

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