Significant Accounting Policies - Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle
Net sales	$ 8,278	$ 7,685
Operating expenses
Cost of sales	4,236	3,882
Selling, general and administrative expenses	2,573	1,614
Research, development and related expenses	486	476
Gain on sale of businesses	(24)	(29)
Total operating expenses	7,271	5,943
Operating income	1,007	1,742
Other expense (income), net	42	5
Income before income taxes	$ 965	1,737
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		7,685
Operating expenses
Cost of sales		3,869
Selling, general and administrative expenses		1,600
Research, development and related expenses		471
Gain on sale of businesses		(29)
Total operating expenses		5,911
Operating income		1,774
Other expense (income), net		37
Income before income taxes		1,737
Change | ASU 2017-07 Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost
Operating expenses
Cost of sales		13
Selling, general and administrative expenses		14
Research, development and related expenses		5
Total operating expenses		32
Operating income		(32)
Other expense (income), net		$ (32)