Accumulated other comprehensive income (loss) (Details 2) - USD ($) $ 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
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other income (expense)									$ (57)		$ (67)		$ 153
Tax (provision) benefit									(1,746)		(1,698)		(3,339)
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
Interest expense excluding Financial Products									(421)		(404)		(531)
Interest expense of Financial Products									754		722		646
Reclassification before tax									7,812		7,822		4,082
Reclassifications net of tax	$ 1,098	$ 1,494	$ 1,620	$ 1,881	$ 1,048	$ 1,727	$ 1,707	$ 1,665	6,093	[1]	6,147	[1]	754	[1]
Financial Products
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Sales and revenues									3,045		2,900
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Reclassifications net of tax									81		127		(9)
Reclassification out of Accumulated Other Comprehensive Income | Foreign currency translation
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other income (expense)									0		(1)		(13)
Tax (provision) benefit									0		0		0
Reclassifications net of tax									0		(1)		(13)
Reclassification out of Accumulated Other Comprehensive Income | Pension and other postretirement benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Tax (provision) benefit									(10)		(8)		(9)
Amortization of prior service credit (cost)									40		36		25
Reclassifications net of tax									30		28		16
Reclassification out of Accumulated Other Comprehensive Income | Derivative financial instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Tax (provision) benefit									(15)		(31)		44
Reclassification before tax									66		131		(121)
Reclassifications net of tax									51		100		(77)
Reclassification out of Accumulated Other Comprehensive Income | Derivative financial instruments | Foreign exchange contracts | Machinery, Energy & Transportation
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other income (expense)									37		115		(121)
Sales and revenues									11		0		0
Cost of goods sold									(3)		0		0
Reclassification out of Accumulated Other Comprehensive Income | Derivative financial instruments | Foreign exchange contracts | Financial Products
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Interest expense of Financial Products									33		19		6
Reclassification out of Accumulated Other Comprehensive Income | Derivative financial instruments | Interest rate contracts | Machinery, Energy & Transportation
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Interest expense excluding Financial Products									(4)		(3)		(9)
Reclassification out of Accumulated Other Comprehensive Income | Derivative financial instruments | Interest rate contracts | Financial Products
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Interest expense of Financial Products									(8)		0		3
Reclassification out of Accumulated Other Comprehensive Income | Available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Other income (expense)									0		0		100
Tax (provision) benefit									0		0		(35)
Reclassifications net of tax									$ 0		$ 0		$ 65

[1] Profit attributable to common shareholders.