Company Restructuring - Changes in the restructuring liability (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Restructuring Reserve
Restructuring liability as of December 31, 2020	$ 72
Expense incurred	55
Adjustments to liability	(4)
Payments and non-cash charges	(82)
Restructuring liability as of March 31, 2021	41
Employee costs
Restructuring Reserve
Restructuring liability as of December 31, 2020	72
Expense incurred	2
Adjustments to liability	(4)
Payments and non-cash charges	(29)
Restructuring liability as of March 31, 2021	41
Exit costs
Restructuring Reserve
Restructuring liability as of December 31, 2020	0
Expense incurred	53
Adjustments to liability	0
Payments and non-cash charges	(53)
Restructuring liability as of March 31, 2021	$ 0