MERGER WITH DUPONT (Details) $ / shares in Units, $ in Millions		9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) $ / shares shares	Aug. 31, 2017 mo $ / shares shares	Aug. 30, 2017 $ / shares	Dec. 31, 2016 $ / shares shares
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.01	$ 0.01			$ 2.50
Common Stock, Shares, Issued | shares	100	100			1,242,794,836
Planned Merger with DuPont, Maximum one-year loss of revenues to Dow for DuPont's proposed transaction with FMC	$ 350
Planned Merger with DuPont, expected number of months for completion of intended spins | mo			18
Dow [Member]
Common Stock, Par or Stated Value Per Share | $ / shares				$ 2.50
DowDuPont [Member]
Common Stock, Par or Stated Value Per Share | $ / shares			$ 0.01
Common Stock, Shares, Issued | shares			100
Treasury Stock [Member]
Stock Repurchased and Retired During Period, Value		$ 935
Common Stock [Member]
Stock Repurchased and Retired During Period, Value		(3,107)
Additional Paid-in Capital [Member]
Stock Repurchased and Retired During Period, Value		$ 2,172