Restructuring and other cost savings initiatives (Details Textual) $ in Millions	Dec. 31, 2017 USD ($)
Separation and other headcount-related costs [Member]
Restructuring Cost and Reserve [Line Items]
Total costs incurred to date	$ 558
Asset-related charges [Member]
Restructuring Cost and Reserve [Line Items]
Total costs incurred to date	239
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expected cost	825
Restructuring expected separation and other headcount-related cost	560
Restructuring expected asset impairments, accelerated depreciation and other related costs	265
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expected cost	900
Restructuring expected separation and other headcount-related cost	600
Restructuring expected asset impairments, accelerated depreciation and other related costs	$ 300