Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Income Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of AOCI	$ 11,222	$ 9,260	$ 7,943
Deferred tax asset on foreign currency translation adjustments	13	11
Deferred tax asset on net charges related to pension/post-retirement plans	1,501	1,805
Total
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of AOCI	(4,575)	(5,110)	(5,055)	$ (4,647)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of AOCI	(1,373)	(984)	(1,543)
Pension and Post-Retirement Plans Losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Components of AOCI	$ (3,202)	$ (4,126)	$ (3,512)