SELECTED QUARTERLY FINANCIAL DATA Reconciliation of First Quarter 2019 (Details) - USD ($) $ in Millions	3 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, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 10,204	$ 10,764	$ 11,014	$ 10,969	$ 11,944	$ 12,634	$ 12,789	$ 12,237	$ 42,951	$ 49,604	$ 43,730
Cost of sales	8,718	9,377	9,420	9,142	10,098	10,456	10,540	9,980	36,657	41,074	36,350
Gross margin	1,486	1,387	1,594	1,827	1,846	2,178	2,249	2,257	6,294	8,530
Restructuring, goodwill impairment and asset related charges - net	2,851	147	65	156	46	48	40	87	3,219	221	2,739
Integration and separation costs 2	99	164	348	452	380	313	262	224	1,063	1,179	798
Income (loss) from continuing operations, net of tax	(2,310)	347	90	156	491	714	810	925	(1,717)	2,940	(1,287)
Income from discontinued operations, net of tax	0	0	0	445	432	335	554	514	445	1,835	1,882
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(2,310)	347	90	601	923	1,049	1,364	1,439	(1,272)	4,775	595
Net income (loss) available for The Dow Chemical Company common stockholder	(2,323)	333	75	556	$ 891	$ 1,013	$ 1,333	$ 1,404	(1,359)	4,641	465
The Dow Chemical Company
Condensed Financial Statements, Captions [Line Items]
Net sales	10,204	10,764	11,014	10,969					42,951	49,604	43,730
Cost of sales	8,719	9,377	9,419	9,142					36,657	41,074	36,350
Gross margin	1,485	1,387	1,595	1,827					6,294
Restructuring, goodwill impairment and asset related charges - net	2,851	147	65	156					3,219	221	2,739
Integration and separation costs 2	99	164	324	452					1,039	1,179	798
Income (loss) from continuing operations, net of tax	(2,292)	324	217	156					(1,595)	2,940	(1,287)
Income from discontinued operations, net of tax	0	0	0	445					445	1,835	1,882
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(2,292)	324	217	601					(1,150)	4,775	595
Net income (loss) available for The Dow Chemical Company common stockholder	$ (2,305)	$ 310	$ 202	556					$ (1,237)	$ 4,641	$ 465
ECP [Member] | The Dow Chemical Company
Condensed Financial Statements, Captions [Line Items]
Net sales				341
Cost of sales				240
Gross margin				101
Restructuring, goodwill impairment and asset related charges - net				2
Integration and separation costs 2				44
Income (loss) from continuing operations, net of tax				15
Income from discontinued operations, net of tax				0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest				15
Net income (loss) available for The Dow Chemical Company common stockholder				15
Previously Reported [Member] | The Dow Chemical Company
Condensed Financial Statements, Captions [Line Items]
Net sales				13,582
Cost of sales				10,707
Gross margin				2,875
Restructuring, goodwill impairment and asset related charges - net				232
Integration and separation costs 2				408
Income (loss) from continuing operations, net of tax				586
Income from discontinued operations, net of tax				0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest				586
Net income (loss) available for The Dow Chemical Company common stockholder				541
Discontinued Operations [Member] | The Dow Chemical Company
Condensed Financial Statements, Captions [Line Items]
Net sales				(2,954)
Cost of sales				1,805
Gross margin				(1,149)
Restructuring, goodwill impairment and asset related charges - net				78
Integration and separation costs 2				0
Income (loss) from continuing operations, net of tax				(445)
Income from discontinued operations, net of tax				445
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest				0
Net income (loss) available for The Dow Chemical Company common stockholder				$ 0