NONCONSOLIDATED AFFILIATES (Impact of Sales to Nonconsolidated Affiliates) (Details) - Equity Method Investee - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
MEGlobal | Customer Concentration Risk
Schedule of Equity Method Investments [Line Items]
Concentration Risk, Percentage	1.00%	1.00%	1.00%
MEGlobal | Customer Concentration Risk | Packaging & Specialty Plastics [Member]
Schedule of Equity Method Investments [Line Items]
Concentration Risk, Percentage	1.00%	1.00%	1.00%
MEGlobal | Customer Concentration Risk | Industrial Intermediates & Infrastructure [Member]
Schedule of Equity Method Investments [Line Items]
Concentration Risk, Percentage	1.00%	2.00%	2.00%
Sadara Chemical Company
Schedule of Equity Method Investments [Line Items]
Concentration Risk, Percentage	8.00%	9.00%	4.00%
Noncurrent receivables, Balance Due From Nonconsolidated Affiliates	$ 0	$ 0
SCG-Dow Group
Schedule of Equity Method Investments [Line Items]
Concentration Risk, Percentage	2.00%	2.00%	3.00%