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RESTRUCTURING AND ASSET RELATED CHARGES - NET (DowDuPont Agriculture Division Restructuring Program) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring, Settlement and Impairment Provisions	$ 232	$ 165
DowDuPont Agriculture Division Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Settlement and Impairment Provisions	(4)		$ 21	$ 25
Restructuring Reserve, Settled without Cash				(1)
Payments for Restructuring	(8)			(1)
Restructuring Reserve	11		11	23
Employee Severance [Member] \| DowDuPont Agriculture Division Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Settlement and Impairment Provisions	(4)		20	24
Restructuring Reserve, Settled without Cash				0
Payments for Restructuring	(8)			(1)
Restructuring Reserve	11		11	23
Asset write-downs and write-offs [Member] \| DowDuPont Agriculture Division Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, Settlement and Impairment Provisions	0		1	1
Restructuring Reserve, Settled without Cash				(1)
Payments for Restructuring	0			0
Restructuring Reserve	0		0	0
Accrued and Other Current Liabilities [Member] \| DowDuPont Agriculture Division Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 11		$ 11	$ 23