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Supplemental Disclosures to the Consolidated Statements of Cash Flows (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2019 | Mar. 31, 2018
Supplemental Cash Flow Information [Abstract] |  |
Deferred and contingent consideration from prior years acquisition | $ 29 | $ 70
Deferred purchase consideration from prior years' acquisitions | 23 | 40
Contingent consideration from prior year's acquisitions | 6 | 30
Net charge for adjustments related to acquisition related accounts | 11 | 5
Payment of contingent consideration | 29 | 10
Non-cash issuance of common stock | 158 | 125
Stock-based compensation expense, equity awards | 57 | 50
Proceeds from issuance of debt | 6,462 | $ 592
Interest income | 25 |
Acquisition-related hedging payments | 129 |
Right-of-use asset, noncash | 1,700 |
Right-to-use liability, noncash | $ 1,900 |

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