Components of Accumulated Other Comprehensive Loss, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (1,706)
Other comprehensive (loss) income, unrecognized amounts on retirement benefits	(65)	$ (59)	$ 25
Other comprehensive (loss) income, foreign currency translation adjustment	233	327	(494)
Other comprehensive (loss) income, unrealized gains on cash flow hedges	(15)	(29)	7
Other comprehensive income (loss)	153	239	(462)
Ending balance	(1,552)	(1,706)
Total shareholders' equity	43,010	32,449
Accumulated Other Comprehensive Loss, Net [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, unrecognized amounts on retirement benefits	(417)	(358)	(383)
Balance, foreign currency translation adjustment	(1,296)	(1,623)	(1,129)
Beginning balance	0	0	1,085
Beginning balance	7	36	29
Beginning balance	(1,706)	(1,945)	(398)
Other comprehensive (loss) income, unrecognized amounts on retirement benefits	(65)	(59)	25
Other comprehensive (loss) income, foreign currency translation adjustment	233	327	(494)
Other comprehensive (loss) income, unrealized gains on available-for-sale securities	0	0	0
Other comprehensive (loss) income, unrealized gains on cash flow hedges	(15)	(29)	7
Other comprehensive income (loss)	153	239	(462)
Balance, unrecognized amounts on retirement benefits	(482)	(417)	(358)
Balance, foreign currency translation adjustment	(1,063)	(1,296)	(1,623)
Ending balance	0	0	0
Ending balance	(8)	7	36
Ending balance	$ (1,553)	$ (1,706)	$ (1,945)
Accumulated Other Comprehensive Loss, Net [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total shareholders' equity				$ (1,085)