Business Combinations Merger with Dow Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	2 Months Ended	3 Months Ended	8 Months Ended	9 Months Ended
	Aug. 31, 2017	Sep. 30, 2017	Aug. 31, 2017	Sep. 30, 2018	Aug. 31, 2017	Sep. 30, 2018	Dec. 31, 2017	Aug. 30, 2017
Business Acquisition [Line Items]
Common Stock, Par Value				$ 0.30		$ 0.30	$ 0.30
Merger with Dow [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 74,680
Goodwill, measurement period adjustments						$ 392
Property, plant and equipment, measurement period adjustments						(257)
Other intangible assets, measurement period adjustment						$ (150)
DuPont [Member]
Business Acquisition [Line Items]
Common Stock, Par Value								$ 0.30
DuPont [Member] | $4.50 Series Preferred Stock [Member]
Business Acquisition [Line Items]
Preferred Stock, Par or Stated Value Per Share				4.50		$ 4.50
DuPont [Member] | $3.50 Series Preferred Stock [Member]
Business Acquisition [Line Items]
Preferred Stock, Par or Stated Value Per Share				$ 3.50		$ 3.50
DowDuPont [Member]
Business Acquisition [Line Items]
Common Stock, Par Value	$ 0.01		$ 0.01		$ 0.01
Common Stock [Member] | Merger with Dow [Member]
Business Acquisition [Line Items]
Share exchange ratio, DuPont to DowDuPont	1.2820
Successor [Member]
Business Acquisition [Line Items]
Integration and Separation Costs		$ 71		$ 344		$ 926
Predecessor [Member]
Business Acquisition [Line Items]
Integration and Separation Costs			$ 210		$ 581