Components of Accumulated Other Comprehensive Loss, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	$ 43,010
Other comprehensive income (loss)	112	$ (547)
Balance	43,089
Accumulated Other Comprehensive (Loss) Income, Net [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(1,552)	(1,706)
Other comprehensive income (loss)	112	(547)
Balance	(1,440)	(2,253)
Unrecognized Amounts On Retirement Benefits [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	482	417
Other comprehensive income (loss)	(7)	(34)
Balance	475	383
Foreign Currency Translation Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(1,062)	(1,296)
Other comprehensive income (loss)	91	(548)
Balance	(971)	(1,844)
Unrealized Gains (Losses) On Cash Flow Hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(8)	7
Other comprehensive income (loss)	14	(33)
Balance	$ 6	$ (26)