Restructuring and Related Activities (DowDupont Cost Synergy Program) (Details) - USD ($) $ in Millions	3 Months Ended					31 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	$ 96				$ 156
The Dow Chemical Company [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	96				156
DowDuPont Cost Synergy Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	118	$ 71	$ 127	$ 159	202	$ 118	$ 217
Restructuring and asset related charges - net	90	33	56	59	144	965
Restructuring Reserve, Settled without Cash		33	5	29	76
Payments for Restructuring	43	56	83	73	83
DowDuPont Cost Synergy Program [Member] | Accrued and Other Current Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	104	52				104
DowDuPont Cost Synergy Program [Member] | Other Noncurrent Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	14	19				14
DowDuPont Cost Synergy Program [Member] | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net					1
DowDuPont Cost Synergy Program [Member] | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	90	26	50	37	143
DowDuPont Cost Synergy Program [Member] | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		5	1	22
DowDuPont Cost Synergy Program [Member] | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		2	5
Employee Severance [Member] | DowDuPont Cost Synergy Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	102	54	106	137	183	102	210
Restructuring and asset related charges - net	90	0	46	25	52	657
Restructuring Reserve, Settled without Cash		0	0	0	0
Payments for Restructuring	42	52	77	71	79
Employee Severance [Member] | DowDuPont Cost Synergy Program [Member] | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net					0
Employee Severance [Member] | DowDuPont Cost Synergy Program [Member] | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	90	0	46	25	52
Employee Severance [Member] | DowDuPont Cost Synergy Program [Member] | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		0	0	0
Employee Severance [Member] | DowDuPont Cost Synergy Program [Member] | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		0	0
Asset write-downs and write-offs [Member] | DowDuPont Cost Synergy Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0	0	0	0	0	0
Restructuring and asset related charges - net	0	33	5	29	76	263
Restructuring Reserve, Settled without Cash		33	5	29	76
Payments for Restructuring	0	0	0	0	0
Asset write-downs and write-offs [Member] | DowDuPont Cost Synergy Program [Member] | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net					0
Asset write-downs and write-offs [Member] | DowDuPont Cost Synergy Program [Member] | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	0	26	4	7	76
Asset write-downs and write-offs [Member] | DowDuPont Cost Synergy Program [Member] | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		5	1	22
Asset write-downs and write-offs [Member] | DowDuPont Cost Synergy Program [Member] | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		2	0
Costs Associated with Exit and Disposal Activities [Member] | DowDuPont Cost Synergy Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	16	17	21	22	19	16	$ 7
Restructuring and asset related charges - net	0	0	5	5	16	$ 45
Restructuring Reserve, Settled without Cash		0	0	0	0
Payments for Restructuring	1	4	6	2	4
Costs Associated with Exit and Disposal Activities [Member] | DowDuPont Cost Synergy Program [Member] | Packaging & Specialty Plastics [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net					1
Costs Associated with Exit and Disposal Activities [Member] | DowDuPont Cost Synergy Program [Member] | Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net	$ 0	0	0	5	$ 15
Costs Associated with Exit and Disposal Activities [Member] | DowDuPont Cost Synergy Program [Member] | Performance Materials & Coatings [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		0	0	$ 0
Costs Associated with Exit and Disposal Activities [Member] | DowDuPont Cost Synergy Program [Member] | Industrial Intermediates & Infrastructure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and asset related charges - net		$ 0	$ 5