Restructuring and Related Implementation Charges - Summary of Restructuring Charges, Cumulative to Date (Details) - Global Growth and Efficiency Program $ in Millions	Dec. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Pretax charges related to the Restructuring Program to date	$ 1,722
Employee-Related Costs
Restructuring Cost and Reserve [Line Items]
Pretax charges related to the Restructuring Program to date	681
Incremental Depreciation
Restructuring Cost and Reserve [Line Items]
Pretax charges related to the Restructuring Program to date	92
Asset Impairments
Restructuring Cost and Reserve [Line Items]
Pretax charges related to the Restructuring Program to date	52
Other
Restructuring Cost and Reserve [Line Items]
Pretax charges related to the Restructuring Program to date	$ 897