Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss	Unearned ESOP Shares [Member]	Noncontrolling Interests	The Dow Chemical Company [Domain]	The Dow Chemical Company [Domain] Common Stock [Member]	The Dow Chemical Company [Domain] Additional Paid-in Capital [Member]	The Dow Chemical Company [Domain] Retained Earnings [Member]	The Dow Chemical Company [Domain] Accumulated Other Comprehensive Loss	The Dow Chemical Company [Domain] Unearned ESOP Shares [Member]	The Dow Chemical Company [Domain] Noncontrolling Interests
ESOP shares acquired						$ 0							$ 0
Total Equity, Beginning at Dec. 31, 2017		$ 0	$ 6,553	$ 33,742	$ (8,591)	(189)			$ 0	$ 6,553	$ 33,742	$ (8,591)	(189)
Stock Issued										0
Stock-based compensation and allocation of ESOP shares			294			50				294			50
Adjustments to Additional Paid in Capital, Other										0
Stock Issued During Period, Value, Parent Company Stock - DWDP			106							106
Net income available for The Dow Chemical Company common stockholder				3,750							3,750
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees				(3,158)							3,158
Transfer of Business Under Common Control	$ (276)			204	0		$ 0	$ 276			204	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				989	(1,037)						989	(1,037)
Other			0	13							(13)
Other comprehensive income	482				482			482				482
Total Equity, Ending at Sep. 30, 2018	33,955	0	6,953	35,106	(9,146)	(139)		33,955		6,953	35,106	(9,146)	(139)	$ 1,181
ESOP shares acquired						0							0
Total Equity, Beginning at Jun. 30, 2018		0	6,861	35,192	(9,387)	(145)			0	6,861	35,192	(9,387)	(145)
Stock Issued										0
Stock-based compensation and allocation of ESOP shares			71			6				71			6
Adjustments to Additional Paid in Capital, Other										0
Stock Issued During Period, Value, Parent Company Stock - DWDP			21							21
Net income available for The Dow Chemical Company common stockholder				1,013							1,013
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees				(1,048)							1,048
Transfer of Business Under Common Control				52	0		0				52	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				0	0						0	0
Other			0	(1)							1
Other comprehensive income	241				241			241				241
Total Equity, Ending at Sep. 30, 2018	33,955	0	6,953	35,106	(9,146)	(139)		33,955		6,953	35,106	(9,146)	(139)	1,181
The Dow Chemical Company’s stockholders’ equity	32,774							32,774
The Dow Chemical Company’s stockholders’ equity	32,483							32,483
ESOP shares acquired						(2)							(2)
Total Equity, Beginning at Dec. 31, 2018	33,621	0	7,042	35,460	(9,885)	(134)		33,621	0	7,042	35,460	(9,885)	(134)
Stock Issued										11
Stock-based compensation and allocation of ESOP shares			202			41				202			41
Adjustments to Additional Paid in Capital, Other										(38)
Stock Issued During Period, Value, Parent Company Stock - DWDP			28							28
Net income available for The Dow Chemical Company common stockholder				964							1,068
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees				(535)							535
Transfer of Business Under Common Control	1,935			14,861	793		353	61			16,022	793
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				(111)	0						(111)	0
Other			37	11							(11)
Other comprehensive income	(127)				(127)			(127)				(127)
Total Equity, Ending at Sep. 30, 2019	17,986	7	7,239	19,873	(9,219)	(95)		18,367		7,245	19,849	(9,219)	(95)	587
ESOP shares acquired						(2)							(2)
Total Equity, Beginning at Jun. 30, 2019		7	7,186	20,110	(8,988)	(99)			$ 0	7,192	19,575	(8,988)	(99)
Stock Issued										5
Stock-based compensation and allocation of ESOP shares			55			6				55			6
Adjustments to Additional Paid in Capital, Other										(7)
Stock Issued During Period, Value, Parent Company Stock - DWDP			0							0
Net income available for The Dow Chemical Company common stockholder				333							310
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees				0							0
Transfer of Business Under Common Control				50	0		$ 0				32	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				0	0						0	0
Other			7	4							(4)
Other comprehensive income	(231)				(231)			(231)				(231)
Total Equity, Ending at Sep. 30, 2019	17,986	$ 7	$ 7,239	$ 19,873	$ (9,219)	$ (95)		18,367		$ 7,245	$ 19,849	$ (9,219)	$ (95)	$ 587
The Dow Chemical Company’s stockholders’ equity	$ 17,399							$ 17,780