Summary of Sundry Income (Expense) - Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Sundry income (expense) - net	$ 128	$ (81)
Gain (Loss) on Extinguishment of Debt		86
Nonoperating Income (Expense)
Sundry income (expense) - net	128	(81)
Gain (Loss) on Extinguishment of Debt	0	(86)
Other Nonoperating Income (Expense)	13	(15)
Gain (Loss) on Disposition of Other Assets	48	9
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	75	27
Foreign Currency Transaction Gain (Loss), before Tax	(8)	(16)
The Dow Chemical Company [Domain]
Sundry income (expense) - net	119	(82)
Gain (Loss) on Extinguishment of Debt	0	(86)
Other Nonoperating Income (Expense)	8	(15)
Gain (Loss) on Disposition of Other Assets	48	9
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	75	27
Foreign Currency Transaction Gain (Loss), before Tax	$ (12)	$ (17)