SELECTED QUARTERLY FINANCIAL DATA (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 15, 2016
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 14,610	$ 14,976	$ 15,793	$ 14,899	$ 14,811	$ 13,633	$ 13,834	$ 13,230	$ 60,278	$ 55,508	$ 48,158
Cost of sales	11,820	11,933	12,400	11,552	11,994	10,663	10,761	10,194	47,705	43,612	37,668
Gross margin	2,790	3,043	3,393	3,347	2,817	2,970	3,073	3,036	12,573	11,896
Restructuring, goodwill impairment and asset related charges - net	249	108	98	165	2,974	139	(12)	(1)	620	3,100	595
Integration and separation costs	333	278	231	202	258	283	136	109	1,044	786	349
Net income (loss)	910	1,036	1,310	1,377	(2,484)	805	1,359	915	4,633	595	4,404
Net income (loss) attributable to The Dow Chemical Company	$ 878	$ 1,000	$ 1,279	$ 1,342	$ (2,526)	$ 783	$ 1,321	$ 888	$ 4,499	$ 466	$ 3,978
Earnings per common share - basic (in dollars per share)							$ 1.08	$ 0.74
Earnings per common share - diluted (in dollars per share)							1.07	0.72
Dividends declared per share of common stock (in dollars per share)						$ 0.46	0.46	0.46		$ 1.38	$ 1.84
Share Price (in dollars per share)												$ 58.35
Maximum
Condensed Financial Statements, Captions [Line Items]
Share Price (in dollars per share)							65.26	65.00
Minimum
Condensed Financial Statements, Captions [Line Items]
Share Price (in dollars per share)							$ 60.20	$ 57.09