Supplemental Disclosures to the Consolidated Statements of Cash Flows (Additional Information Concerning Acquisitions, Interest And Income Taxes Paid) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Supplemental Cash Flow Information [Abstract]
Assets acquired, excluding cash	$ 180	$ 35
Liabilities assumed	(5)	(4)
Contingent/deferred purchase consideration	(35)	(7)
Net cash outflow for current year acquisitions	140	24
Interest paid	98	80
Income taxes paid, net of refunds	$ 131	$ 128