Components of Accumulated Other Comprehensive Loss, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Loss, Net [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 1,085
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(398)
Other comprehensive (loss) income, unrecognized amounts on retirement benefits	25	$ 64	$ (9)
Other comprehensive (loss) income, foreign currency translation adjustment	(494)	546	(583)
Other comprehensive (loss) income, unrealized gains on available-for-sale securities	0	500	(30)
Other comprehensive (loss) income, unrealized gains on cash flow hedges	7	3	19
Other comprehensive income (loss)	(462)	1,113	(603)
Ending balance	(1,945)	(398)
Accumulated Other Comprehensive Loss, Net [Member]
Accumulated Other Comprehensive Loss, Net [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(1,085)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance, unrecognized amounts on retirement benefits	(383)	(447)	(438)
Balance, foreign currency translation adjustment	(1,129)	(1,675)	(1,092)
Beginning balance	1,085	585	615
Beginning balance	29	26	7
Beginning balance	(398)	(1,511)	(908)
Other comprehensive (loss) income, unrecognized amounts on retirement benefits	25	64	(9)
Other comprehensive (loss) income, foreign currency translation adjustment	(494)	546	(583)
Other comprehensive (loss) income, unrealized gains on available-for-sale securities	0	500	(30)
Other comprehensive (loss) income, unrealized gains on cash flow hedges	7	3	19
Other comprehensive income (loss)	(462)	1,113	(603)
Balance, unrecognized amounts on retirement benefits	(358)	(383)	(447)
Balance, foreign currency translation adjustment	(1,623)	(1,129)	(1,675)
Ending balance	0	1,085	585
Ending balance	36	29	26
Ending balance	$ (1,945)	$ (398)	$ (1,511)