Company Restructuring - Changes in the restructuring liability (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Restructuring Reserve
Restructuring liability as of December 31, 2018	$ 44
Expense incurred	16
Adjustments to liability	2
Payments	(15)
Restructuring liability as of March 31, 2019	47
Employee costs
Restructuring Reserve
Restructuring liability as of December 31, 2018	29
Expense incurred	16
Adjustments to liability	2
Payments	(11)
Restructuring liability as of March 31, 2019	36
Exit costs
Restructuring Reserve
Restructuring liability as of December 31, 2018	15
Expense incurred	0
Adjustments to liability	0
Payments	(4)
Restructuring liability as of March 31, 2019	$ 11