Segment Information (Schedule of Revenues By Geographic Area Based On The Location of Customers) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 39,350	$ 36,193	$ 30,973
North America
Segment Reporting Information [Line Items]
Revenue	32,834	29,333	24,434
North America | United States
Segment Reporting Information [Line Items]
Revenue	31,982	28,578	23,519
North America | Other North America
Segment Reporting Information [Line Items]
Revenue	852	755	915
Europe
Segment Reporting Information [Line Items]
Revenue	2,808	2,772	2,558
Asia Pacific
Segment Reporting Information [Line Items]
Revenue	1,670	2,252	2,011
Africa Middle East
Segment Reporting Information [Line Items]
Revenue	1,739	1,565	1,655
South America
Segment Reporting Information [Line Items]
Revenue	299	271	315
International Operations
Segment Reporting Information [Line Items]
Revenue	$ 4,400	$ 4,200	$ 3,700