Acquisitions (Allocation Of Acquisition Costs) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Cash	$ 160	$ 420
Estimated fair value of deferred/contingent consideration	32	90
Total Consideration	192	510
Allocation of purchase price:
Goodwill	9,177	$ 8,821	$ 9,089	$ 8,369
Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Cash	160
Estimated fair value of deferred/contingent consideration	32
Total Consideration	192
Allocation of purchase price:
Cash and cash equivalents	16
Accounts receivable, net	12
Property, plant, and equipment	3
Other intangible assets	73
Goodwill	116
Total assets acquired	220
Current liabilities	10
Other liabilities	18
Total liabilities assumed	28
Net assets acquired	$ 192