Restructuring and other impairment charges - expected costs to be incurred (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
2016 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	$ 34
2016 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	44
2014 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	46	$ 43
2014 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	51	$ 48
Termination benefits | 2016 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	14
Termination benefits | 2016 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	15
Termination benefits | 2014 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	11
Termination benefits | 2014 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	12
Facility closure and other exit costs | 2016 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2
Facility closure and other exit costs | 2016 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	3
Facility closure and other exit costs | 2014 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	1
Facility closure and other exit costs | 2014 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	2
Special Termination Benefits And Facility Closing | 2016 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	16
Special Termination Benefits And Facility Closing | 2016 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	18
Special Termination Benefits And Facility Closing | 2014 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	12
Special Termination Benefits And Facility Closing | 2014 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	14
Accelerated Depreciation Charges | 2016 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	16
Accelerated Depreciation Charges | 2016 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	18
Accelerated Depreciation Charges | 2014 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	34
Accelerated Depreciation Charges | 2014 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	37
Other | 2016 Manufacturing footprint realignment plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	18
Other | 2016 Manufacturing footprint realignment plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	$ 26