Earnings Per Share of Common Stock Net Income for EPS Calc Basic and Diluted (Details) - USD ($) $ in Millions	3 Months Ended																4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2019	[1]	Sep. 30, 2019	[2],[3]	Jun. 30, 2019	[4]	Mar. 31, 2019	[5]	Dec. 31, 2018	[4],[5],[6]	Sep. 30, 2018	[6],[7]	Jun. 30, 2018	[6],[8]	Mar. 31, 2018	[6],[9]	Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
(Loss) income from continuing operations after income taxes	$ (42)		$ (527)		$ 483		$ (184)		$ (1,070)		$ (5,642)		$ 375		$ (438)		$ 1,760	$ 358	$ (270)	$ (6,775)
Net Income attributable to continuing operations - Noncontrolling Interest																	10	8	13	29
Net (Loss) Income from Continuing Operations Available to Common Shareholders																	1,750	350	(283)	(6,804)
(Loss) income from discontinued operations after income taxes																	(568)	1,403	(671)	1,748
Loss from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest																	0	19	5	9
Net (Loss) Income from Discontinued Operations Available to Common Shareholders																	(568)	1,384	(676)	1,739
Net (Loss) Income Available to Common Stockholders																	$ 1,182	$ 1,734	$ (959)	$ (5,065)

[1] 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.

[2] 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. 

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

[4] 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.

[5] 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.

[6] 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.

[7] 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.

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

[9] 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.