MERGER WITH DUPONT (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2019	Apr. 01, 2019	Dec. 31, 2018	Sep. 01, 2017	Aug. 31, 2017
Common stock, par value (in dollars per share)		$ 0.01		$ 0.01
Common stock issued (in shares)		751,228,644		100
Treasury Stock [Member]
Stock Repurchased and Retired During Period, Value	$ 935
Common Stock
Stock Repurchased and Retired During Period, Value	3,107
Add'l Paid-in Capital
Stock Repurchased and Retired During Period, Value	$ 2,172
The Dow Chemical Company
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 2.50
Dow to DowDuPont Share Exchange Ratio for Common Shares						1
Common stock issued (in shares)		100		100	100
DowDuPont
Common stock, par value (in dollars per share)			$ 0.01			$ 0.01