Restructuring (Details) $ in Millions	Sep. 30, 2018 USD ($)
Separation and Other Headcount-related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Total costs incurred to date	$ 547
Asset-related Charges [Member]
Restructuring Cost and Reserve [Line Items]
Total costs incurred to date	251
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Expected pre-tax accounting charges	800
Separation and other headcount-related costs	540
Accelerated depreciation and asset impairment and other related charges	260
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Expected pre-tax accounting charges	850
Separation and other headcount-related costs	560
Accelerated depreciation and asset impairment and other related charges	$ 290