Components of Accumulated Other Comprehensive Loss, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - Accumulated other comprehensive loss, net	$ (1,945)
Other comprehensive income (loss), unrecognized amounts on retirement benefits	(32)	$ (3)
Other comprehensive income (loss), foreign currency translation adjustment	155	73
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges	(8)	(2)
Other comprehensive income (loss)	115	68
Ending balance - Accumulated other comprehensive loss, net	(1,830)
Accumulated Other Comprehensive (Loss) Income, Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(1,085)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - unrecognized amounts on retirement benefits	(358)	(383)
Beginning balance - foreign currency translation adjustment	(1,623)	(1,129)
Beginning balance - unrealized gains (losses) on available-for-sale securities	0	1,085
Beginning balance - unrealized gains (losses) on cash flow hedges	36	29
Beginning balance - Accumulated other comprehensive loss, net	(1,945)	(398)
Other comprehensive income (loss), unrecognized amounts on retirement benefits	(32)	(3)
Other comprehensive income (loss), foreign currency translation adjustment	155	73
Unrealized gains on marketable securities, net of tax	0	0
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges	(8)	(2)
Other comprehensive income (loss)	115	68
Ending balance - unrecognized amounts on retirement benefits	(390)	(386)
Ending balance - foreign currency translation adjustment	(1,468)	(1,056)
Ending balance - unrealized gains (losses) on available-for-sale securities	0	0
Ending balance - unrealized gains (losses) on cash flow hedges	28	27
Ending balance - Accumulated other comprehensive loss, net	$ (1,830)	$ (1,415)