Selected quarterly financial results (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Sales and revenues	$ 13,144	$ 12,758	$ 14,432	$ 13,466	$ 14,342	$ 13,510	$ 14,011	$ 12,859	$ 53,800		$ 54,722		$ 45,462
Cost of goods sold	9,117	8,569	9,941	9,003	9,987	9,022	9,422	8,566	36,630		36,997		31,260
Gross margin	3,269	3,405	3,730	3,721	3,643	3,741	3,857	3,584
Profit (loss)	$ 1,098	$ 1,494	$ 1,620	$ 1,881	$ 1,048	$ 1,727	$ 1,707	$ 1,665	$ 6,093	[1]	$ 6,147	[1]	$ 754	[1]
Profit (loss) per common share	$ 2.00	$ 2.69	$ 2.85	$ 3.29	$ 1.80	$ 2.92	$ 2.86	$ 2.78	$ 10.85		$ 10.39		$ 1.27
Profit (loss) per common share - diluted	$ 1.97	$ 2.66	$ 2.83	$ 3.25	$ 1.78	$ 2.88	$ 2.82	$ 2.74	$ 10.74	[2]	$ 10.26	[2]	$ 1.26	[2]
Pre-tax pension and other postretirement benefit plan actuarial losses	$ (468)				$ (495)				$ (468)		$ (495)		$ (301)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount											(25)
Charge/ (benefit) to U.S. deferred tax rate change 2017 U.S. tax reform						$ 154					$ 154
Taxes at U. S. statutory rate (as a percent)									21.00%		21.00%		35.00%
Correction of Prior Year Valuation Allowance						59					$ 59		$ (17)
Valuation allowances									$ 0		(29)		(111)
Adjustment to estimated tax for mandatory deemed repatriation of non-U.S. earnings				$ 178	50				178		50
U.S. 2017 tax reform estimated impact													2,371
U.S. state taxing jurisdictions
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount					(63)						(63)
Valuation allowances													(111)
Financial Products
Sales and revenues	758	$ 784	$ 761	742	712	747	$ 732	$ 709	3,045		2,900		2,786
Machinery, Energy & Transportation
Sales and revenues	$ 12,386	$ 11,974	$ 13,671	$ 12,724	$ 13,630	$ 12,763	$ 13,279	$ 12,150	$ 50,755		$ 51,822		$ 42,676

[1] Profit attributable to common shareholders.

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