Segment Reporting Significant Items (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Segment Reporting Information [Line Items]
Significant Items		$ (246)		$ (369)		$ (886)		$ (876)
Restructuring and Asset Related (Charges) Benefits - Net		46		235		167		466
Integration and Separation Costs		152		253		694		697
Loss on early extinguishment of debt		0		0		(13)		0
Exchange (gains) losses - net	[1]	(11)		(74)		(70)		(190)	[2]
Merger with Dow [Member]
Segment Reporting Information [Line Items]
Amortization of inventory step up included in COGS		15		109		272		1,424
Hedging Program [Member]
Segment Reporting Information [Line Items]
Exchange (gains) losses - net		55		31		(11)		27	[3]
Argentine peso devaluation [Member] | Hedging Program [Member]
Segment Reporting Information [Line Items]
Exchange (gains) losses - net		(42)		(40)		(33)		(73)
Tax Reform Foreign Currency Exchange Impact [Member] | Hedging Program [Member]
Segment Reporting Information [Line Items]
Exchange (gains) losses - net								(50)
Seed [Member]
Segment Reporting Information [Line Items]
Significant Items	[5]	(62)	[4]	(190)		(214)	[4],[6]	(249)	[7]
Restructuring and Asset Related (Charges) Benefits - Net		(47)		(190)		(123)		(273)
Gain (Loss) on Disposition of Assets						(24)		24
Seed [Member] | Merger with Dow [Member]
Segment Reporting Information [Line Items]
Amortization of inventory step up included in COGS		(15)				(67)
Crop Protection [Member]
Segment Reporting Information [Line Items]
Significant Items	[8]	1		(30)		(24)		(42)
Restructuring and Asset Related (Charges) Benefits - Net		1		(30)		(24)		(42)
Corporate
Segment Reporting Information [Line Items]
Significant Items	[9]	(185)	[10]	(149)	[11]	(648)	[10],[11],[12]	(585)	[11],[13]
Restructuring and Asset Related (Charges) Benefits - Net				(15)		(20)		(151)
Integration and Separation Costs		(152)
Integration costs				$ (134)		(582)		(384)
Loss on early extinguishment of debt						(13)
Corporate | Argentine peso devaluation [Member] | Hedging Program [Member]
Segment Reporting Information [Line Items]
Exchange (gains) losses - net		$ (33)				$ (33)
Corporate | Tax Reform Foreign Currency Exchange Impact [Member] | Hedging Program [Member]
Segment Reporting Information [Line Items]
Exchange (gains) losses - net								$ (50)

[1] Includes net pre-tax exchange losses of $(33) million and $(42) million for the three and nine months ended September 30, 2019, respectively and $(40) million and $(73) million for the three and nine months ended September 30, 2018, respectively, associated with the devaluation of the Argentine peso.

[2] Includes a $(50) million foreign exchange loss for the nine months ended September 30, 2018 related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform, which is included within significant items.

[3] Includes a $(50) million foreign exchange loss for the nine months ended September 30, 2018 related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform.

[4] Includes charges of $(15) million and $(67) million included in cost of goods sold for the three and nine months ended September 30, 2019 related to the amortization on the inventory that was stepped up to fair value in connection with the Merger.

[5] Includes restructuring and asset related charges of $(47) million and $(123) million for the three and nine months ended September 30, 2019, respectively, and $(190) million and $(273) million for the three and nine months ended September 30, 2018, respectively. See Note 7 - Restructuring and Asset Related Charges - Net, for additional information.

[6] Includes a $(24) million loss recorded in other income - net for the nine months ended September 30, 2019 related to Historical Dow’s sale of a joint venture related to synergy actions.

[7] Includes a $24 million gain recorded in other income - net for the nine months ended September 30, 2018, related to an asset sale.

[8] Includes restructuring and asset related benefits (charges) of $1 million and $(24) million for the three and nine months ended September 30, 2019, respectively, and $(30) million and $(42) million for the three and nine months ended September 30, 2018, respectively. See Note 7 - Restructuring and Asset Related Charges - Net, for additional information.

[9] Includes integration and separation costs of $(152) million and $(582) million for the three and nine months ended September 30, 2019. Includes integration costs of $(134) million and $(384) million for the three and nine months ended September 30, 2018, respectively.

[10] Includes a $(33) million charge included in other income - net for the three and nine months ended September 30, 2019 associated with remeasuring the company’s Argentine Peso net monetary assets, resulting from an unexpected August primary election result in Argentina.  Throughout the three months ended September 30, 2019, the Argentine Peso dropped approximately a third of its value against the US dollar and in September of 2019, the country’s central bank announced new restrictions on foreign currency transactions.

[11] Includes restructuring and asset related charges of $(20) million for the nine months ended September 30, 2019, and $(15) million and $(151) million for the three and nine months ended September 30, 2018, respectively. See Note 7 - Restructuring and Asset Related Charges - Net, for additional information.

[12] Includes a $(13) million loss included in loss on early extinguishment of debt for the nine months ended September 30, 2019 related to the difference between the redemption price and the par value of the Make Whole Notes and Term Loan Facility, partially offset by the write-off of unamortized step-up related to the fair value step-up of EID’s debt.

[13] Includes a $(50) million foreign exchange loss for the nine months ended September 30, 2018 related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform.