Quaterly Financial Data Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Net Sales	$ 2,983		$ 1,911		$ 5,556		$ 3,396		$ 2,815		$ 1,947		$ 5,731		$ 3,794		$ 3,790	$ 6,894	$ 13,846	$ 14,287
Cost of Goods Sold	1,968		1,349	[1]	3,047	[1]	2,211	[1]	2,024	[1]	1,485	[1]	3,687	[1]	2,752	[1]	2,915	3,409	8,575	9,948
Restructuring and Asset Related Charges - Net	55	[2]	46	[2]	60	[2]	61	[2]	228	[2]	235	[2]	101	[2]	130	[2]	270	12	222	694
Integration and Separation Costs	50	[2]	152	[2]	330	[2]	212	[2]	295	[2]	253	[2]	249	[2]	195	[2]	255		744	992
Goodwill Impairment Charge									0		4,503	[2]	0		0		0	0	0	4,503
(Loss) income from continuing operations after income taxes	(42)	[3]	(527)	[4],[5]	483	[6]	(184)	[7]	(1,070)	[6],[7],[8]	(5,642)	[8],[9]	375	[8],[10]	(438)	[8],[11]	1,760	358	(270)	(6,775)
Net (loss) income attributable to Company	$ (21)	[2]	$ (494)	[2]	$ (608)	[2]	$ 164	[2]	$ (531)	[2]	$ (5,121)	[2]	$ 694	[2]	$ (107)	[2]	$ 1,182	$ 1,734	$ (959)	$ (5,065)
(Loss) earnings per common share, continuing operations - basic	$ (0.06)	[12]	$ (0.69)	[12]	$ 0.63	[12]	$ (0.26)	[12]	$ (1.43)	[12]	$ (7.54)	[12]	$ 0.49	[12]	$ (0.60)	[12]	$ 2.34	$ 0.40	$ (0.38)	$ (9.08)
(Loss) earnings per common share, continuing operations - diluted	$ (0.06)	[12]	$ (0.69)	[12]	$ 0.63	[12]	$ (0.26)	[12]	$ (1.43)	[12]	$ (7.54)	[12]	$ 0.49	[12]	$ (0.60)	[12]	$ 2.34	$ 0.40	$ (0.38)	$ (9.08)

[1] Includes charges of $(639) million, $(676) million, $(109) million, and $(130) million for the first quarter 2018, second quarter 2018, third quarter 2018, and fourth quarter 2018, respectively, and $(205) million, $(52) million, and $(15) million for the first quarter 2019, second quarter 2019, and third quarter 2019, respectively, related to the amortization of inventory step-up as a result of the Merger.

[2] Note 7 - Restructuring and Asset Related Charges - Net, Note 5 - Divestitures and Other Transactions, and Note 15 - Goodwill and Other Intangible Assets, for additional information related to integration and separation costs, restructuring and asset related charges - net, discontinued operations, and goodwill impairment charge, respectively.

[3] Fourth quarter 2019 includes a tax benefit of $34 million related to the impact of the release of a tax valuation allowance recorded against the net deferred tax asset position of a Switzerland legal entity. See Note 10 - Income Taxes, for additional information.

[4] Third quarter 2019 includes a $(33) million charge included in other income (expense) - net associated with remeasuring the company’s Argentine Peso net monetary assets, resulting from an unexpected August primary election result in Argentina. 

[5] Third quarter 2019 includes a tax benefit of $38 million related to Swiss Tax Reform. See Note 10 - Income Taxes, for additional information.

[6] Includes a loss on early extinguishment of debt of $(13) million in the second quarter of 2019 and $(81) million in the fourth quarter 2018 related to the retirement of some of the company's debt. See Note 17 - Short-Term Borrowings, Long-Term Debt and Available Credit Facilities, for additional information.

[7] First quarter 2019 includes a $(24) million loss recorded in other income (expense) - net related to Historical Dow’s sale of a joint venture related to synergy actions. Fourth quarter 2018 includes a $(53) million loss recorded in other income (expense) - net related to the deconsolidation of a subsidiary.

[8] Includes tax (charges) benefits of $(64) million, $(7) million, $16 million, and $(274) million in the first quarter 2018, second quarter 2018, third quarter 2018, and fourth quarter 2018, respectively, related to The Act. See Note 10 - Income Taxes, for additional information.

[9] Includes a tax charge of $(75) million in the third quarter 2018 related to the establishment of a full valuation allowance against the net deferred tax asset position of a legal entity in Brazil, a tax charge of $(25) million related to an internal legal entity restructuring associated with the Business Separations, and a tax benefit of $114 million related to the company's discretionary pension contribution in 2018 which was deducted on a 2017 tax return. See Note 10 - Income Taxes, for additional information.

[10] Second quarter 2018 includes a $24 million gain recorded in other income (expense) - net related to an asset sale.

[11] First quarter 2018 includes a $(50) million foreign exchange loss related to adjustments to foreign currency exchange contracts as a result of U.S. tax reform.

[12] Earnings per share for the year may not equal the sum of quarterly earnings per share due to rounding and the changes in average share calculations.