Accumulated Other Comprehensive Losses (Components of Accumulated Other Comprehensive Earnings (Losses), Net of Tax) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	$ (10,245)	$ (10,120)	$ (9,599)	$ (9,155)	$ (9,409)	$ (10,739)
Currency translation adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	(6,910)		(5,537)	(5,649)
Pension and other benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	(3,606)		(3,829)	(3,306)
Derivatives accounted for as hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	(51)		3	(11)
Accumulated Other Comprehensive Losses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	$ (10,567)	$ (10,009)	$ (9,363)	$ (8,966)	$ (9,051)	$ (10,111)