Inventories Schedule of Inventory (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Sep. 01, 2017
Inventory [Line Items]
Finished Products	$ 2,295	$ 2,649	$ 2,295	$ 2,649	$ 3,022
Semi-finished Products	1,691	1,902	1,691	1,902	1,821
Inventory, Raw Materials and Supplies, Gross	417	347	417	347	467
Total	4,403	4,898	4,403	4,898	$ 5,310
Merger with Dow [Member]
Inventory [Line Items]
Business Combination, Fair Value Step Up Of Acquired Inventory						$ 2,297
Amortization of inventory step up included in COGS	$ 15	$ 109	$ 272	$ 1,424