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Restructuring Actions and Exit Activities - Roll Forward (Details) - USD ($) $ in Millions	6 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2018
2018 Restructuring Actions
Restructuring Reserve Roll Forward
Expenses incurred			$ 137
Non-cash changes	$ (12)
Cash payments	(24)
Adjustments	(17)
Restructuring actions balances, Ending Balance	84		84	$ 84
Employee-Related \| 2018 Restructuring Actions
Restructuring Reserve Roll Forward
Expenses incurred			125
Cash payments	(24)
Adjustments	(17)
Restructuring actions balances, Ending Balance	84		84	84
Employee-Related \| 2017 Restructuring Actions
Restructuring Reserve Roll Forward
Restructuring actions balances, Beginning Balance		$ 99		88
Cash payments		(8)		(20)
Adjustments		(3)		(28)
Restructuring actions balances, Ending Balance	40	$ 88	40	$ 40
Asset-Related \| 2018 Restructuring Actions
Restructuring Reserve Roll Forward
Expenses incurred			$ 12
Non-cash changes	$ (12)