Preparation Of Interim Financial Statements (Consolidated Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Other cost of services	$ 8,651	$ 9,694	$ 24,215	$ 28,551
Selling, general and administrative	9,598	8,650	26,179	25,981
Operating Income (Loss)	7,269	5,807	19,936	18,689
Other income (expense) - net	1,053	842	5,108	2,255
Net income	4,816	3,123	14,823	10,711
Historical Accounting Method [Member] | Adjustments for New Accounting Pronouncement [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Other cost of services	8,527	9,431	23,166	27,714
Selling, general and administrative	9,207	8,317	22,859	24,917
Operating Income (Loss)	7,784	6,403	24,305	20,590
Other income (expense) - net	538	246	739	354
Net income	4,816	3,123	14,823	10,711
Effect of Adoption | ASU 2017-07
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Other cost of services	124	263	1,049	837
Selling, general and administrative	391	333	3,320	1,064
Operating Income (Loss)	(515)	(596)	(4,369)	(1,901)
Other income (expense) - net	515	596	4,369	1,901
Net income	$ 0	$ 0	$ 0	$ 0