RESTRUCTURING, GOODWILL IMPAIRMENT AND ASSET RELATED CHARGES - NET (2020 Restructuring Program)(Details) - USD ($) $ in Millions	3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net	$ (11)	$ 617	$ 6	$ 96	$ 2,851	$ 147	$ 65	$ 156		$ 708	$ 3,219	$ 221
The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net										708	3,219	221
Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net										30	439	46
Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net										22	1,175	11
Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net										192	1,076	21
Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net										464	$ 529	$ 143
2020 Restructuring Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net		575							$ 573
Charges against the reserve	(201)								(201)
Cash payments	(8)								(8)
Restructuring Reserve	364								364	364
2020 Restructuring Program [Member] | Accrued and Other Current Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	227								227	227
2020 Restructuring Program [Member] | Other Noncurrent Obligations
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 137								$ 137	$ 137
2020 Restructuring Program [Member] | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
restructuring and related cost, percentage	6.00%								6.00%	6.00%
Restructuring, goodwill impairment and asset related charges - net	$ 573
2020 Restructuring Program [Member] | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									$ 11
2020 Restructuring Program [Member] | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									22
2020 Restructuring Program [Member] | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									177
2020 Restructuring Program [Member] | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									363
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net		197							196
Charges against the reserve									(196)
Cash payments									0
Restructuring Reserve	0								0	$ 0
Restructuring Reserve, Accrual Adjustment	1
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									196
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									11
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Packaging & Specialty Plastics [Member] | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									11
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									22
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Industrial Intermediates & Infrastructure [Member] | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									22
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									116
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Performance Materials & Coatings [Member] | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									116
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									47
2020 Restructuring Program [Member] | Asset Write-downs and Write-offs | Corporate Segment [Member] | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									47
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net		81							80
Charges against the reserve	(5)								(5)
Cash payments	0								0
Restructuring Reserve	75								75	75
Restructuring Reserve, Accrual Adjustment	1
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									19
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									56
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net	80								80
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									0
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									0
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									61
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Performance Materials & Coatings [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									9
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Performance Materials & Coatings [Member] | Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									52
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									19
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Corporate Segment [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									10
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Corporate Segment [Member] | Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									4
2020 Restructuring Program [Member] | Costs Associated with Exit and Disposal Activities | Corporate Segment [Member] | Pension Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									5
2020 Restructuring Program [Member] | Severance and Related Benefit Costs
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net		$ 297
Charges against the reserve									0
Cash payments									(8)
Restructuring Reserve	$ 289								289	$ 289
2020 Restructuring Program [Member] | Severance and Related Benefit Costs | The Dow Chemical Company
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									297
Cash payments									(8)
2020 Restructuring Program [Member] | Severance and Related Benefit Costs | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									0
2020 Restructuring Program [Member] | Severance and Related Benefit Costs | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									0
2020 Restructuring Program [Member] | Severance and Related Benefit Costs | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									0
2020 Restructuring Program [Member] | Severance and Related Benefit Costs | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring, goodwill impairment and asset related charges - net									$ 297