Operations and summary of significant accounting policies (Details 3 - Revenue recognition) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016		Jan. 01, 2018
Revenue recognition new guidance impact-Statement of financial position
Receivables - trade and other	$ 8,802				$ 7,436				$ 8,802		$ 7,436				$ 7,370
Prepaid expenses and other current assets	1,765				1,772				1,765		1,772				2,099
Inventories	11,529				10,018				11,529		10,018				10,022
Property, plant and equipment - net	13,574				14,155				13,574		14,155				13,965
Noncurrent deferred and refundable income taxes	1,439				1,693				1,439		1,693				1,695
Accrued expenses	3,573				3,220				3,573		3,220				3,446
Customer advances	1,243				1,426				1,243		1,426				1,472
Other current liabilities	1,919				1,742				1,919		1,742				1,725
Other liabilities	3,756				4,053				3,756		4,053				3,887
Profit employed in the business	30,427				26,301				30,427		26,301				26,289
Revenue recognition new guidance impact - Results of operations
Sales of machinery, energy & transportation	14,342	$ 13,510	$ 14,011	$ 12,859	12,896	$ 11,413	$ 11,331	$ 9,822	54,722		45,462		$ 38,537
Cost of goods sold	9,987	9,022	9,422	8,566	8,965	7,678	7,816	6,801	36,997		31,260		28,044
Other operating (income) expenses									1,382		2,255		1,904
Operating profit									8,293		4,460		1,162
Consolidated profit before taxes									7,822		4,082		139
Provision (benefit) for income taxes									1,698		3,339		192
Profit (loss) of consolidated companies									6,124		743		(53)
Profit (loss) of consolidated and affiliated companies									6,148		759		(59)
Profit (loss)	1,048	1,727	1,707	1,665	(1,299)	1,059	802	192	6,147	[1]	754	[1]	(67)	[1]
Accounting Standards Update 2014-09
Revenue recognition new guidance impact-Statement of financial position
Receivables - trade and other	(63)								(63)						(66)
Prepaid expenses and other current assets	360								360						327
Inventories	6								6						4
Property, plant and equipment - net															(190)
Noncurrent deferred and refundable income taxes	(3)								(3)						2
Accrued expenses	232								232						226
Customer advances	61								61						46
Other current liabilities															(17)
Other liabilities															(166)
Profit employed in the business	7								7						$ (12)
Revenue recognition new guidance impact - Results of operations
Cost of goods sold									(10)
Other operating (income) expenses									(6)
Operating profit									24
Consolidated profit before taxes									24
Provision (benefit) for income taxes									5
Profit (loss) of consolidated companies									19
Profit (loss) of consolidated and affiliated companies									19
Profit (loss)									19
Machinery, Energy & Transportation
Revenue recognition new guidance impact - Results of operations
Sales of machinery, energy & transportation	13,630	$ 12,763	$ 13,279	$ 12,150	$ 12,194	$ 10,713	$ 10,639	$ 9,130	51,822		$ 42,676		$ 35,773
Machinery, Energy & Transportation | Accounting Standards Update 2014-09
Revenue recognition new guidance impact - Results of operations
Sales of machinery, energy & transportation									8
Previous Accounting Method
Revenue recognition new guidance impact-Statement of financial position
Receivables - trade and other	8,865								8,865
Prepaid expenses and other current assets	1,405								1,405
Inventories	11,523								11,523
Noncurrent deferred and refundable income taxes	1,442								1,442
Accrued expenses	3,341								3,341
Customer advances	1,182								1,182
Profit employed in the business	$ 30,420								30,420
Revenue recognition new guidance impact - Results of operations
Cost of goods sold									37,007
Other operating (income) expenses									1,388
Operating profit									8,269
Consolidated profit before taxes									7,798
Provision (benefit) for income taxes									1,693
Profit (loss) of consolidated companies									6,105
Profit (loss) of consolidated and affiliated companies									6,129
Profit (loss)									6,128
Previous Accounting Method | Machinery, Energy & Transportation
Revenue recognition new guidance impact - Results of operations
Sales of machinery, energy & transportation									$ 51,814

[1] 1 Profit (loss) attributable to common shareholders.