Segment Reporting Significant Items (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2019		Jun. 30, 2018
Segment Reporting Information [Line Items]
Significant Items		$ (455)		$ (203)		$ (640)		$ (507)
Restructuring and Asset Related Charges - Net		60		101		121		231
Integration and Separation Costs		330		249		542		444
Loss on early extinguishment of debt		13		0		13		0
Exchange losses - net		(32)		(1)		(59)		(116)	[1]
Seed [Member]
Segment Reporting Information [Line Items]
Significant Items	[3]	(101)	[2]	(37)		(152)	[2],[4]	(83)
Restructuring and Asset Related Charges - Net		(49)		(37)		(76)		(83)
Gain (Loss) on Disposition of Assets						(24)
Crop Protection [Member]
Segment Reporting Information [Line Items]
Significant Items		(2)	[5]	24	[6]	(25)	[5]	12	[5],[6]
Restructuring and Asset Related Charges - Net		(2)				(25)		(12)
Gain (Loss) on Disposition of Assets				24				24
Corporate
Segment Reporting Information [Line Items]
Significant Items	[8],[9]	(352)	[7]	(190)		(463)	[7]	(436)	[10]
Restructuring and Asset Related Charges - Net		(9)		(64)		(20)		(136)
Integration and Separation Costs		(330)
Integration costs				(126)		(430)		(250)
Loss on early extinguishment of debt		(13)				(13)
Merger with Dow [Member]
Segment Reporting Information [Line Items]
Business Combination, Fair Value Step-Up Of Acquired Inventory, Amount recognized in Cost of Goods sold		52		676		257		1,315
Merger with Dow [Member] | Seed [Member]
Segment Reporting Information [Line Items]
Business Combination, Fair Value Step-Up Of Acquired Inventory, Amount recognized in Cost of Goods sold		(52)				(52)
Hedging Program [Member]
Segment Reporting Information [Line Items]
Exchange losses - net		$ (49)		$ 177		$ (66)		(4)	[11]
Tax Reform Foreign Currency Exchange Impact [Member] | Hedging Program [Member] | Corporate
Segment Reporting Information [Line Items]
Exchange losses - net								$ (50)

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

[2] Includes a charge of $(52) million included in cost of goods sold for the three and six months ended June 30, 2019 related to the amortization on the inventory that was stepped up to fair value in connection with the Merger.

[3] Includes restructuring and asset related charges of $(49) million and $(76) million for the three and six months ended June 30, 2019, respectively, and $(37) million and $(83) million for the three and six months ended June 30, 2018, respectively. The charges for 2019 relate to the Synergy Program and the DowDuPont Agriculture Division Restructuring Program. The charges for 2018 related to the Synergy Program.

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

[5] Includes restructuring and asset related charges of $(2) million and $(25) million for the three and six months ended June 30, 2019, respectively, and $(12) million for the six months ended June 30, 2018. The charges for 2019 relate to the Synergy Program and the DowDuPont Agriculture Division Restructuring Program. The charges for 2018 related to the Synergy Program.

[6] Includes a $24 million gain recorded in other income - net for the three and six months ended June 30, 2018, related to an asset sale.

[7] Includes a $(13) million loss included in loss on early extinguishment of debt for the three and six months ended June 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.

[8] Includes integration and separation costs of $(330) million and $(430) million for the three and six months ended June 30, 2019. Includes integration costs of $(126) million and $(250) million for the three and six months ended June 30, 2018, respectively.

[9] Includes restructuring and asset related charges of $(9) million and $(20) million for the three and six months ended June 30, 2019, respectively, and $(64) million and $(136) million for the three and six months ended June 30, 2018, respectively. The charges for 2019 and 2018 related to the Synergy Program

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

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