Property, plant and equipment - Schedule of property, plant and equipment (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Land	$ 396	$ 394
Buildings and Improvements, Gross	2,176	1,713
Machinery and Equipment, Gross	533	469
Office And Computer Equipment Gross	494	466
Construction in Progress, Gross	690	641
Property, Plant and Equipment, Gross	4,289	3,683
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(994)	(818)
Property, Plant and Equipment, Net	$ 3,295	$ 2,865