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Supplemental Disclosures (Schedule of Supplemental Cash Flow Disclosures) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Supplemental Cash Flow Information [Abstract] |  |  |
Assets acquired, excluding cash | $ 929 | $ 8,655 | $ 1,100
Liabilities assumed | (78) | (2,804) | (83)
Non-controlling interests assumed | 0 | (280) | 0
Contingent and deferred purchase consideration | (183) | (66) | (133)
Net cash outflow for acquisitions | 668 | 5,505 | 884
Interest paid | 481 | 427 | 264
Income taxes paid, net of refunds | $ 673 | $ 661 | $ 632

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