NONCONSOLIDATED AFFILIATES (Schedule of the Company's Direct or Indirect Ownership Interest in Principal Nonconsolidated Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Investment in nonconsolidated affiliates	$ 1,404	$ 3,320	$ 3,107
Other noncurrent obligations	(80)	0
Net investment in principal nonconsolidated affiliates	1,324	3,320
Equity in earnings (losses) of nonconsolidated affiliates	$ (94)	$ 555	$ 394
EQUATE Petrochemical Company K.S.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	42.50%	42.50%	42.50%
Investment in nonconsolidated affiliates		$ 131
Other noncurrent obligations	$ (80)
The Kuwait Olefins Company K.S.C.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	42.50%	42.50%	42.50%
The Kuwait Styrene Company KSC
Schedule of Equity Method Investments [Line Items]
Ownership percentage	42.50%	42.50%	42.50%
Map Ta Phut Olefins Company
Schedule of Equity Method Investments [Line Items]
Ownership percentage	32.77%	32.77%	32.77%
Equity Method Investment, Ownership Percentage, Direct	20.27%
Equity Method Investment, Ownership Percentage, Indirect	12.50%
Sadara Chemical Company
Schedule of Equity Method Investments [Line Items]
Ownership percentage	35.00%	35.00%	35.00%
Siam Polyethylene Company Limited
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%	50.00%
Siam Polystyrene Company Limited
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%	50.00%
Siam Styrene Monomer Company Limited
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%	50.00%
Siam Synthetic Latex Company Limited
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%	50.00%
Principal Nonconsolidated Affiliates
Schedule of Equity Method Investments [Line Items]
Investment in nonconsolidated affiliates	$ 963	$ 2,876
Other noncurrent obligations	80	0
Net investment in principal nonconsolidated affiliates	883	2,876
Equity in earnings (losses) of nonconsolidated affiliates	$ 21	$ 561	$ 347

Equity Method Investment, Liability, Noncurrent

No definition available.

Name:	dow_EquityMethodInvestmentLiabilityNoncurrent
Namespace Prefix:	dow_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Equity Method Investment, Net of Investment Liabilities

+ References

No definition available.

+ Details

Name:	dow_EquityMethodInvestmentNetofInvestmentLiabilities
Namespace Prefix:	dow_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Equity Method Investment, Ownership Percentage, Direct

+ References

No definition available.

+ Details

Name:	dow_EquityMethodInvestmentOwnershipPercentageDirect
Namespace Prefix:	dow_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Equity Method Investment, Ownership Percentage, Indirect

+ References

No definition available.

+ Details

Name:	dow_EquityMethodInvestmentOwnershipPercentageIndirect
Namespace Prefix:	dow_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of income (loss) for proportionate share of equity method investee's income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(12))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(10))
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(f))
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570

+ Details

Name:	us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_EquatePetrochemicalCompanyKscMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_KuwaitOlefinsCompanyKscMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_TheKuwaitStyreneCompanyKSCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_MapTaPhutOlefinsCompanyDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_SadaraChemicalCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_SiamPolyethyleneCompanyLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_SiamPolystyreneCompanyLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_SiamStyreneMonomerCoLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_SiamSyntheticLatexCompanyLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=dow_PrincipalNonconsolidatedAffiliatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: