FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS (Summary of Nonrecurring Measured Fair Values) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	$ 617	$ 147	$ 719	$ 368
Asset Impairment Charges	46		58
The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	617	147	719	368
Manufacturing Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	7	16	19	$ 34
Non-manufacturing Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	24
Leased, Non-manufacturing Facilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges			39
Performance Materials & Coatings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges			15
Corporate Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges			24
2020 Restructuring Program [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	575
2020 Restructuring Program [Member] | The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	575
2020 Restructuring Program [Member] | Packaging & Specialty Plastics [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	11
2020 Restructuring Program [Member] | Industrial Intermediates & Infrastructure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	22
2020 Restructuring Program [Member] | Performance Materials & Coatings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	174
2020 Restructuring Program [Member] | Corporate Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	368
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	197
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	197
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Packaging & Specialty Plastics [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	11
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Packaging & Specialty Plastics [Member] | The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	11
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Industrial Intermediates & Infrastructure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	22
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Industrial Intermediates & Infrastructure [Member] | The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	22
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Performance Materials & Coatings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	117
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Performance Materials & Coatings [Member] | The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	117
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Corporate Segment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	47
Asset write-downs and write-offs [Member] | 2020 Restructuring Program [Member] | Corporate Segment [Member] | The Dow Chemical Company [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring and asset related charges - net	47
Fair Value, Nonrecurring [Member] | Manufacturing Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges		75
Fair Value, Nonrecurring [Member] | Non-manufacturing Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	15
Fair Value, Nonrecurring [Member] | Packaging & Specialty Plastics [Member] | Manufacturing Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges		24	19
Fair Value, Nonrecurring [Member] | Corporate Segment [Member] | Manufacturing Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges		$ 51
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Non-manufacturing Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	11		11
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Leased, Non-manufacturing Facilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 110		$ 110