Dow Inc. Consolidated Statements of Comprehensive Income Statement - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (2,310)	$ 347	$ 90	$ 601	$ 923	$ 1,049	$ 1,364	$ 1,439	$ (1,272)	$ 4,775	$ 595
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on investments									115	(67)	(46)
Cumulative translation adjustments									(32)	(225)	900
Pension and other postretirement benefit plans									(899)	(40)	391
Derivative instruments									(338)	75	(14)
Total other comprehensive income (loss)									(1,154)	(257)	1,231
Comprehensive income (loss)									(2,426)	4,518	1,826
Comprehensive income attributable to noncontrolling interests, net of tax									99	97	172
Comprehensive income (loss) attributable to Dow Inc.									$ (2,525)	$ 4,421	$ 1,654