Inventories Narrative (Details) - Successor [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended					4 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Sep. 01, 2017
Inventory [Line Items]
Business Combination, Fair Value Step-Up Of Acquired Inventory, Amount recognized in Cost of Goods sold	$ (360)	$ (134)	$ (109)	$ (682)	$ (703)	$ (1,109)	$ (1,469)	$ (1,628)
Merger with Dow [Member]
Inventory [Line Items]
Business Combination, Fair Value Step Up Of Acquired Inventory									$ 3,840
Business Combination, Fair Value Step-Up Of Acquired Inventory, Amount recognized in Cost of Goods sold							$ (1,434)	$ (1,563)