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Supplemental Disclosures to the Consolidated Statements of Cash Flows (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2020 | Mar. 31, 2019
Supplemental Cash Flow Information [Abstract] |  |
Deferred and contingent consideration from prior years acquisition | $ 29 | $ 29
Deferred purchase consideration from prior years' acquisitions | 25 | 23
Contingent consideration from prior year's acquisitions | 4 | 6
Net charge for adjustments related to acquisition related accounts | 1 | 11
Payment of contingent consideration | 9 | 29
Non-cash issuance of common stock | 201 | 158
Stock-based compensation expense, equity awards | 72 | 57
Proceeds from issuance of debt | $ 0 | 6,462
Proceeds from interest earned |  | 25
Payments on acquisition related derivative contracts |  | $ 129

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