Significant Accounting Policies - Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle
Net sales	$ 8,152	$ 8,172	$ 24,820	$ 23,667
Operating expenses
Cost of sales	4,159	4,059	12,622	11,961
Selling, general and administrative expenses	1,547	1,637	5,920	4,871
Research, development and related expenses	430	468	1,384	1,422
Gain on sale of businesses			(530)	(490)
Total operating expenses	6,136	6,164	19,396	17,764
Operating income	2,016	2,008	5,424	5,903
Other expense (income), net	51	11	144	27
Income before income taxes	$ 1,965	1,997	$ 5,280	5,876
Previously Reported | ASU 2017-07 Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost
New Accounting Pronouncements or Change in Accounting Principle
Net sales		8,172		23,667
Operating expenses
Cost of sales		4,045		11,921
Selling, general and administrative expenses		1,623		4,830
Research, development and related expenses		463		1,407
Gain on sale of businesses				(490)
Total operating expenses		6,131		17,668
Operating income		2,041		5,999
Other expense (income), net		44		123
Income before income taxes		1,997		5,876
Change | ASU 2017-07 Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost
Operating expenses
Cost of sales		14		40
Selling, general and administrative expenses		14		41
Research, development and related expenses		5		15
Total operating expenses		33		96
Operating income		(33)		(96)
Other expense (income), net		$ (33)		$ (96)