REVERSE MORRIS TRUST TRANSACTION Reverse Morris Trust (Details) - USD ($) $ in Millions			9 Months Ended		12 Months Ended
		Oct. 05, 2015	Sep. 30, 2015	[3]	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Principal Amount of Subsidiary New Debt Instruments Exchanged		$ 1,220
Gains (Losses) on Extinguishment of Debt					$ 0	$ (8)	$ 0
Dow Shares Exchange in Share Exchange Offer		34,100,000
Number of Splitco shares exchanged		100,000,000
Conversion Factor, number of Olin Shares for each share of Splitco		0.87482759
Number of Olin shares distributed in share exchange		87,500,000
Shareholder Ownership Percentage in Olin		52.70%
Increase in Treasury Stock from Share Exchange, Noncash		$ 1,523
Costs associated with portfolio and productivity actions					33	0	0
Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent reduction in outstanding shares		3.00%
Disposal Group, Including Discontinued Operation, Pension Plan Benefit Obligation		$ 439
Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Principal Amount of Subsidiary New Debt Instruments Exchanged		1,220
Principal Amount of the Company's Debt Exchanged		1,154
Extinguishment of Debt, Amount		1,161
Proceeds from Issuance of Debt		875
Accounts and notes receivable - Trade		263
Inventories		338
Other current assets		111
Net property		1,531
Goodwill		71
Other noncurrent assets		44
Total assets divested		2,358
Long-term debt due within one year (1)	[1]	51
Other current liabilities		116
Long-Term Debt (1)	[1]	518
Deferred income tax liabilities		265
Pension and other postretirement benefits - noncurrent		439
Total liabilities divested		1,389
Components of accumulated other comprehensive loss divested		(215)
Net carrying value divested		1,184
Disposal Group, Including Discontinued Operation, Consideration		3,510
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		2,233			6	2,233	0
Disposal Group Not Discontinued Operation Gain (Loss) On Disposal After Tax		2,215
Income Before Income Taxes (2)	[2]		$ 139				281
Loss before income taxes attributable to noncontrolling interests			(11)				(5)
Income Before Income Taxes attributable to The Dow Chemical Company (2)	[2]		$ 150				286
Costs associated with portfolio and productivity actions						$ 119	$ 49
Ethylene Supply Agreement [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred Revenue		434
Deferred Revenue, Current		16
Deferred Revenue, Noncurrent		$ 418
Chlor-Alkali joint venture [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		50.00%				50.00%
Chlor-Alkali joint venture [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Extinguishment of Debt, Amount		$ 569
Loss on purchase of Redeemable Noncontrolling Interest included in disposal group		25
Chlor-Alkali joint venture [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments for Repurchase of Redeemable Noncontrolling Interest		133
Performance Materials & Chemicals [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable - Trade		269
Inventories		297
Other current assets		5
Net property		1,268
Goodwill		71
Other noncurrent assets		9
Total assets divested		1,919
Long-term debt due within one year (1)	[1]	0
Other current liabilities		99
Long-Term Debt (1)	[1]	0
Deferred income tax liabilities		0
Pension and other postretirement benefits - noncurrent		0
Total liabilities divested		99
Components of accumulated other comprehensive loss divested		0
Net carrying value divested		1,820
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		1,984
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, post closing adjustments					6
Performance Plastics [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable - Trade		0
Inventories		34
Other current assets		6
Net property		205
Goodwill		0
Other noncurrent assets		1
Total assets divested		246
Long-term debt due within one year (1)	[1]	0
Other current liabilities		17
Long-Term Debt (1)	[1]	0
Deferred income tax liabilities		0
Pension and other postretirement benefits - noncurrent		0
Total liabilities divested		17
Components of accumulated other comprehensive loss divested		0
Net carrying value divested		229
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		317
Corporate, Non-Segment [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts and notes receivable - Trade		(6)
Inventories		7
Other current assets		100
Net property		58
Goodwill		0
Other noncurrent assets		34
Total assets divested		193
Long-term debt due within one year (1)	[1]	51
Other current liabilities		0
Long-Term Debt (1)	[1]	518
Deferred income tax liabilities		265
Pension and other postretirement benefits - noncurrent		439
Total liabilities divested		1,273
Components of accumulated other comprehensive loss divested		(215)
Net carrying value divested		(865)
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		(68)
Corporate, Non-Segment [Member] | Tender Offer of Long Term Debt [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gains (Losses) on Extinguishment of Debt		$ (68)				$ (68)
Pension Plan [Member] | Performance Materials & Chemicals [Member] | Chlorine Value Chain [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, post closing adjustments					$ 5

[1] Excludes $1,161 million included as part of the debt exchange offer and $875 million from a term loan entered into under the terms of the Transaction. See Note 17 for additional information.

[2] Excludes transaction costs associated with the separation of the chlorine value chain, which are reported below.

[3] Income statement information for 2015 includes results through September 30, 2015.