Supplemental financial information - Property, plant and equipment at cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	$ 5,425	$ 4,789
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	128	127
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	$ 2,497	2,467
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost, depreciable lives	5 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost, depreciable lives	40 years
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	$ 2,800	$ 2,195
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost, depreciable lives	2 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost, depreciable lives	10 years