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Restructuring Actions and Exit Activities - Roll Forward (Details) - Employee-Related - USD ($) $ in Millions	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Sep. 30, 2018
2018 Restructuring Actions
Restructuring Reserve Roll Forward
Expenses incurred		$ 105
Cash payments	$ (12)
Adjustments	(7)
Restructuring actions balances, Ending Balance	86				$ 86
2017 Restructuring Actions
Restructuring Reserve Roll Forward
Restructuring actions balances, Beginning Balance					88
Expenses incurred			$ 99
Cash payments				$ (8)	(17)
Adjustments				(3)	(27)
Restructuring actions balances, Ending Balance	$ 44			$ 88	$ 44