SEGMENTS AND GEOGRAPHIC REGIONS Significant Items - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gain (Loss) Related to Litigation Settlement		$ 544	$ 205
Charges related to separation, distribution and tax matters agreements		(21)	(144)
Gain (loss) on divestiture		717	(49)
Integration and separation costs		(239)	(1,013)	$ (1,074)
Restructuring, goodwill impairment and asset related charges - net		(708)	(3,219)	(198)
Loss on early extinguishment of debt		(149)	(102)	(54)
Accrual for Environmental Loss Contingencies, Revision in Estimates	$ 399		(399)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties		11	39
Other Nonrecurring (Income) Expense		145	(4,682)	(1,326)
Restructuring Implementation Costs		(10)
Packaging & Specialty Plastics [Member]
Gain (Loss) Related to Litigation Settlement		544	170
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net				0
Charges related to separation, distribution and tax matters agreements		0	0
Gain (loss) on divestiture		52	0	0
Integration and separation costs		0	0	0
Restructuring, goodwill impairment and asset related charges - net		(30)	(439)	(46)
Loss on early extinguishment of debt		0	0	0
Accrual for Environmental Loss Contingencies, Revision in Estimates	5		(5)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties		0	0
Other Nonrecurring (Income) Expense		566	(274)	(46)
Restructuring Implementation Costs		0
Industrial Intermediates & Infrastructure [Member]
Gain (Loss) Related to Litigation Settlement		0	0
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net				0
Charges related to separation, distribution and tax matters agreements		0	0
Gain (loss) on divestiture		61	(5)	20
Integration and separation costs		0	0	0
Restructuring, goodwill impairment and asset related charges - net		(22)	(1,175)	(11)
Loss on early extinguishment of debt		0	0	0
Accrual for Environmental Loss Contingencies, Revision in Estimates	8		(8)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties		0	0
Other Nonrecurring (Income) Expense		39	(1,188)	9
Restructuring Implementation Costs		0
Performance Materials & Coatings [Member]
Gain (Loss) Related to Litigation Settlement		0	0
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net				(20)
Charges related to separation, distribution and tax matters agreements		0	0
Gain (loss) on divestiture		0	0	0
Integration and separation costs		0	0	0
Restructuring, goodwill impairment and asset related charges - net		(192)	(1,076)	(21)
Loss on early extinguishment of debt		0	0	0
Accrual for Environmental Loss Contingencies, Revision in Estimates	50		(50)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties		0	0
Other Nonrecurring (Income) Expense		(192)	(1,126)	(41)
Restructuring Implementation Costs		0
Corporate Segment [Member]
Gain (Loss) Related to Litigation Settlement		0	35
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net				0
Charges related to separation, distribution and tax matters agreements		(21)	(144)
Gain (loss) on divestiture		604	(44)	0
Integration and separation costs		(239)	(1,013)	(1,074)
Restructuring, goodwill impairment and asset related charges - net		(464)	(529)	(120)
Loss on early extinguishment of debt		(149)	(102)	(54)
Accrual for Environmental Loss Contingencies, Revision in Estimates	$ 336		(336)
Standard and Extended Product Warranty Accrual, Increase (Decrease) for Preexisting Warranties		11	39
Other Nonrecurring (Income) Expense		(268)	(2,094)	(1,248)
Restructuring Implementation Costs		(10)
Dow Silicones Corporation
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net		$ 0	$ 0	(20)
MEGlobal
Gain (loss) on divestiture				$ 20