Accumulated Other Comprehensive Losses (Components of Accumulated Other Comprehensive Earnings (Losses), Net of Tax) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	$ (11,063)	$ (9,599)	$ (10,185)	$ (10,739)
Currency translation adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	(7,039)	(5,537)	(5,711)
Pension and other benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	(3,755)	(3,829)	(3,556)
Derivatives accounted for as hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	20	3	30
Accumulated Other Comprehensive Losses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total accumulated other comprehensive losses	$ (10,774)	$ (9,363)	$ (9,237)	$ (10,111)