Segment Information (Schedule Of Revenue from External Customers Attributed to Foreign Countries by Geographic Area) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 25,368	$ 24,309	$ 22,739	$ 20,976	$ 23,286	$ 23,898	$ 24,755	$ 22,632	$ 93,392	$ 94,571	$ 96,114
Non-U.S. [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									51,061	55,806	56,827
Asia, Other Than China [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									8,899	10,553	13,433
Europe [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									11,457	13,790	12,248
China [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									11,911	10,312	12,556
Middle East [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									12,287	13,297	10,846
Oceania [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									2,061	1,843	2,601
Canada [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									2,197	2,076	1,870
Africa [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									755	1,999	1,398
Latin America, Caribbean And Other [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									1,494	1,936	1,875
United States [member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 42,331	$ 38,765	$ 39,287