SUPPLEMENTARY INFORMATION Sundry - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary Information [Line Items]
Net loss on sales of property	$ 0	$ (1)	$ 0
Gain (Loss) on Extinguishment of Debt	(19)	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(20)	(17)	(1)
Other - net	(11)	(12)	(9)
Total sundry income (expense) - net	168	(82)	(62)
Administrative and overhead fees [Member] | The Dow Chemical Company [Member]
Supplementary Information [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	(31)	(24)	(30)
Net Commission Expense [Member] | The Dow Chemical Company [Member]
Supplementary Information [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	(22)	(23)	(22)
Acetone Derivatives [Member]
Supplementary Information [Line Items]
Net loss on sales of property	0	(5)	0
Marine and Terminal Operations and Assets [Member]
Supplementary Information [Line Items]
Net loss on sales of property	185	0	0
Rail Infrastructure Operations and Assets [Member]
Supplementary Information [Line Items]
Net loss on sales of property	$ 86	$ 0	$ 0