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