2018 Global Restructuring Program Narrative (Details) $ in Millions	12 Months Ended		24 Months Ended	36 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) Employee
Restructuring Cost and Reserve
Restructuring liabilities recorded in accrued expenses	$ 93	$ 118	$ 93
2018 Global Restructuring Program
Restructuring Cost and Reserve
Restructuring liabilities recorded in accrued expenses	93	118	93
Restructuring liabilities recorded in other liabilities	39	92	39
2018 Global Restructuring Program | After Tax
Restructuring Cost and Reserve
Restructuring Charges	248	793	1,000
2018 Global Restructuring Program | Before Tax
Restructuring Cost and Reserve
Restructuring Charges	$ 366	$ 1,036	$ 1,400
2018 Global Restructuring Program | Minimum | Scenario, Forecast
Restructuring Cost and Reserve
Expected Number of Positions Eliminated | Employee				5,000
2018 Global Restructuring Program | Minimum | After Tax | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				$ 1,300
Restructuring and Related Cost, Expected Cost Remaining				235
2018 Global Restructuring Program | Minimum | Before Tax | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				1,700
Restructuring and Related Cost, Expected Cost Remaining				300
2018 Global Restructuring Program | Minimum | Cash charges | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				900
2018 Global Restructuring Program | Minimum | Non-cash charges | Before Tax | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				$ 800
2018 Global Restructuring Program | Maximum | Scenario, Forecast
Restructuring Cost and Reserve
Expected Number of Positions Eliminated | Employee				5,500
2018 Global Restructuring Program | Maximum | After Tax | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				$ 1,400
Restructuring and Related Cost, Expected Cost Remaining				390
2018 Global Restructuring Program | Maximum | Before Tax | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				1,900
Restructuring and Related Cost, Expected Cost Remaining				500
2018 Global Restructuring Program | Maximum | Cash charges | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				1,000
2018 Global Restructuring Program | Maximum | Non-cash charges | Before Tax | Scenario, Forecast
Restructuring Cost and Reserve
Restructuring and Related Cost, Expected Cost				$ 900