Property, plant and equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, plant and equipment
Total property, plant and equipment, at cost	$ 31,940	$ 31,977
Less: Accumulated depreciation	(16,618)	(15,887)
Property, plant and equipment - net	15,322	16,090
Commitments for the purchase or construction of capital assets	142
Assets recorded under capital leases
Gross capital leases	99	124
Less: Accumulated depreciation	(22)	(44)
Net capital leases	77	80
Minimum rental payments on assets recorded under capital leases were:
2017	7
2018	6
2019	6
2020	6
2021	20
Thereafter	30
Minimum rental payments to be received for equipment leased to others were:
2017	892
2018	600
2019	349
2020	167
2021	67
Thereafter	64
Land
Property, plant and equipment
Total property, plant and equipment, at cost	667	644
Buildings and land improvements
Property, plant and equipment
Total property, plant and equipment, at cost	7,383	7,242
Machinery, equipment and other
Property, plant and equipment
Total property, plant and equipment, at cost	15,392	15,686
Software
Property, plant and equipment
Total property, plant and equipment, at cost	1,641	1,636
Equipment leased to others
Property, plant and equipment
Total property, plant and equipment, at cost	6,086	5,728
Less: Accumulated depreciation	(1,659)	(1,571)
Property, plant and equipment - net	4,427	4,157
Construction-in-process
Property, plant and equipment
Total property, plant and equipment, at cost	$ 771	$ 1,041
Minimum | Buildings and land improvements
Property, plant and equipment
Useful Lives (Years)	20 years
Minimum | Machinery, equipment and other
Property, plant and equipment
Useful Lives (Years)	3 years
Minimum | Software
Property, plant and equipment
Useful Lives (Years)	3 years
Minimum | Equipment leased to others
Property, plant and equipment
Useful Lives (Years)	1 year
Maximum | Buildings and land improvements
Property, plant and equipment
Useful Lives (Years)	45 years
Maximum | Machinery, equipment and other
Property, plant and equipment
Useful Lives (Years)	10 years
Maximum | Software
Property, plant and equipment
Useful Lives (Years)	7 years
Maximum | Equipment leased to others
Property, plant and equipment
Useful Lives (Years)	7 years