Acquisitions and Dispositions (Allocation Of Acquisition Costs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Cash	$ 142	$ 29
Estimated fair value of deferred/contingent consideration	35	7
Total consideration	177	36
Allocation of purchase price:
Goodwill	9,739	$ 9,194	$ 9,599	$ 9,089
Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Cash	142
Estimated fair value of deferred/contingent consideration	35
Total consideration	177
Allocation of purchase price:
Cash and cash equivalents	2
Accounts receivable, net	5
Property, plant, and equipment	1
Other intangible assets	71
Goodwill	97
Other assets	6
Total assets acquired	182
Current liabilities	5
Other liabilities	0
Total liabilities assumed	5
Net assets acquired	$ 177