Acquisitions and Dispositions (Allocation Of Acquisition Costs) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Cash	$ 576	$ 5,859
Estimated fair value of deferred/contingent consideration	161	66
Total consideration	737	5,925
Allocation of purchase price:
Goodwill	14,797	$ 14,479	$ 14,671	$ 9,599
Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Cash	576
Estimated fair value of deferred/contingent consideration	161
Total consideration	737
Allocation of purchase price:
Cash and cash equivalents	14
Accounts receivable, net	28
Fixed assets, net	16
Other intangible assets	277
Goodwill	466
Deferred tax assets	(43)
Other assets	8
Total assets acquired	766
Current liabilities	19
Other liabilities	10
Total liabilities assumed	29
Net assets acquired	$ 737