CONSOLIDATED FINANCIAL STATEMENTS Changes to Balance Sheet (Details) - USD ($) $ in Millions	Apr. 01, 2018	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	$ 1,057
Inventories		$ 9,346	$ 8,365	$ 8,376
Other current assets		898	687	627
Total current assets		28,286	27,293	27,244
Deferred income tax assets		1,672	1,757	1,722
Deferred charges and other assets		1,009	872	829
Total other assets		21,811	22,116	22,038
Total assets		80,221	80,067	79,940
Accounts payable - Other		3,939	3,072	3,062
Income taxes payable		736	692	694
Accrued and other current liabilities		3,294	4,075	4,025
Total current liabilities		16,892	14,435	14,377
Other noncurrent obligations		5,930	6,111	5,994
Total other noncurrent liabilities		18,190	18,906	18,789
Retained earnings		29,536	27,982	28,050
Accumulated other comprehensive loss		(9,387)	(8,571)	(8,591)
The Dow Chemical Company's stockholders' equity		26,865	25,775	25,823
Total equity		28,017	26,961	27,009	$ 29,589	$ 27,229
Total Liabilities and Equity		80,221	80,067	$ 79,940
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories		24	(11)
Other current assets		(36)	29
Total current assets		(12)	18
Deferred income tax assets		(27)	25
Deferred charges and other assets		(43)	43
Total other assets		(70)	68
Total assets		(82)	86
Accounts payable - Other		(10)	10
Income taxes payable		2	(2)
Accrued and other current liabilities		(19)	50
Total current liabilities		(27)	58
Other noncurrent obligations		(134)	117
Total other noncurrent liabilities		(134)	117
Retained earnings		79	(89)
Accumulated other comprehensive loss			0
The Dow Chemical Company's stockholders' equity		79	(89)
Total equity		79	(89)
Total Liabilities and Equity		$ (82)	86
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories			0
Other current assets			0
Total current assets			0
Deferred income tax assets			0
Deferred charges and other assets			0
Total other assets			0
Total assets			0
Accounts payable - Other			0
Income taxes payable			0
Accrued and other current liabilities			0
Total current liabilities			0
Other noncurrent obligations			0
Total other noncurrent liabilities			0
Retained earnings			(20)
Accumulated other comprehensive loss			20
The Dow Chemical Company's stockholders' equity			0
Total equity			0
Total Liabilities and Equity			0
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Inventories			0
Other current assets			31
Total current assets			31
Deferred income tax assets			10
Deferred charges and other assets			0
Total other assets			10
Total assets			41
Accounts payable - Other			0
Income taxes payable			0
Accrued and other current liabilities			0
Total current liabilities			0
Other noncurrent obligations			0
Total other noncurrent liabilities			0
Retained earnings			41
Accumulated other comprehensive loss			0
The Dow Chemical Company's stockholders' equity			41
Total equity			41
Total Liabilities and Equity			$ 41