Supplemental financial information - Property, plant and equipment at cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	$ 5,781	$ 5,740
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	125	126
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment at cost	$ 2,571	2,504
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	$ 3,085	$ 3,110
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