Restructuring Actions and Exit Activities - Roll Forward (Details) - Employee-Related - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
2018 Restructuring Actions
Restructuring Reserve Roll Forward
Expenses incurred	$ 105
Cash payments	(6)
Restructuring actions balances, Ending Balance	99		$ 99
2017 Restructuring Actions
Restructuring Reserve Roll Forward
Restructuring actions balances, Beginning Balance			88
Expenses incurred		$ 99
Cash payments			(13)	$ (8)
Adjustments			(27)	(3)
Restructuring actions balances, Ending Balance	$ 48		$ 48	$ 88