Nature of Operations, Basis of Presentation and Change in Accounting Principle (Details 2) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2016
Statement of Results of Operations
Cost of goods sold		$ 8,566	$ 6,801
Selling, general and administrative expenses		1,276	1,061
Research and development expenses		443	425
Other operating (income) expenses		300	996
Total operating costs		10,751	9,442
Operating profit		2,108	380
Other income (expense)		127	32
Consolidated profit before taxes		2,134	289
Provision (benefit) for income taxes		472	90
Profit (loss) of consolidated companies		1,662	199
Profit of consolidated and affiliated companies		1,667	194
Profit	[1]	$ 1,665	$ 192
Profit per common share (in dollars per share)		$ 2.78	$ 0.33
Profit per common share - diluted (in dollars per share)	[2]	$ 2.74	$ 0.32
Statement of Comprehensive Income
Profit of consolidated and affiliated companies		$ 1,667	$ 194
Foreign currency translation, net of tax		184	147
Total other comprehensive income (loss), net of tax		187	212
Comprehensive income		1,854	406
Comprehensive income attributable to stockholders		1,852	404
Statement of Financial Position
Noncurrent deferred and refundable income taxes		1,687		$ 1,695	$ 1,693
Liability for postemployment benefits		8,233			8,365
Profit employed in the business		27,929		26,289	26,301
Accumulated other comprehensive income (loss)		(1,016)	(1,827)	(1,203)	(1,192)		$ (2,039)
Statement of Shareholders' Equity
Profit of consolidated and affiliated companies		1,667	194
Foreign currency translation, net of tax		184	147
Pension and other postretirement benefits, net of tax		(9)	4
Total stockholders' equity		15,272	13,660	$ 13,719	$ 13,766	$ 13,228	$ 13,213
Statement of Cash Flow
Profit of consolidated and affiliated companies		1,667	194
Adjustments for non-cash items: Other		148	302
Other assets - net		165	(261)
Other liabilities - net		7	(64)
Previous Accounting Guidance
Statement of Results of Operations
Cost of goods sold		8,560
Other operating (income) expenses		306
Operating profit		2,103
Consolidated profit before taxes		2,129
Provision (benefit) for income taxes		471
Profit (loss) of consolidated companies		1,658
Profit of consolidated and affiliated companies		1,663
Profit		1,661
Statement of Comprehensive Income
Profit of consolidated and affiliated companies		1,663
Statement of Financial Position
Noncurrent deferred and refundable income taxes		1,686
Profit employed in the business		27,937
Statement of Shareholders' Equity
Profit of consolidated and affiliated companies		1,663
Statement of Cash Flow
Profit of consolidated and affiliated companies		$ 1,663
Previously Reported
Statement of Results of Operations
Cost of goods sold			6,758
Selling, general and administrative expenses			1,045
Research and development expenses			418
Other operating (income) expenses			1,025
Total operating costs			9,405
Operating profit			417
Other income (expense)			$ (5)

[1] 1 Profit attributable to common shareholders.

[2] 2 Diluted by assumed exercise of stock-based compensation awards using the treasury stock method.