Company Restructuring - Changes in the restructuring liability (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Restructuring Reserve
Restructuring liability as of December 31, 2020	$ 72
Expense incurred	170
Adjustments to liability	(25)
Payments and non-cash charges	(163)
Restructuring liability as of September 30, 2021	54
Employee costs
Restructuring Reserve
Restructuring liability as of December 31, 2020	72
Expense incurred	50
Adjustments to liability	(25)
Payments and non-cash charges	(51)
Restructuring liability as of September 30, 2021	46
Exit costs
Restructuring Reserve
Restructuring liability as of December 31, 2020	0
Expense incurred	120
Adjustments to liability	0
Payments and non-cash charges	(112)
Restructuring liability as of September 30, 2021	$ 8