Business Combinations Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended					4 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Aug. 31, 2017
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Goodwill		$ 40,686				$ 45,589	$ 45,589	$ 40,686
Merger with Dow [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Cash and Equivalents									$ 4,005
Marketable Securities									2,849
Accounts and Notes Receivable									7,834
Inventories									8,805
Other current assets									420
Investment in nonconsolidated affiliates									1,596
Assets held for sale - current									3,732
Property, plant and equipment									11,684
Property, plant and equipment measurement period adjustments								(257)
Goodwill									45,497
Goodwill, Measurement Period Adjustments								392
Other intangible assets									27,071
Other intangible assets measurement period adjustments								(150)
Deferred income taxes									279
Other assets									2,066
Total assets									115,838
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Short Term Borrowings and capital lease obligations									5,319
Accounts Payable									3,298
Income Taxes Payable									261
Accrued and other current liabilities									3,517
Liabilities Held For Sale Current									125
Long-term Debt									9,878
Deferred Tax Liabilities									8,259
Pension And Other Postretirement Benefits Noncurrent									8,056
Other Noncurrent Obligations									1,967
Total Liabilities									40,680
Noncontrolling interest									239
Noncontrolling interest measurement period adjustments								61
Preferred Stock									239
Fair value of net assets									74,680
Successor [Member]
Business Acquisition [Line Items]
Business Combination, Fair Value Step-Up Of Acquired Inventory, Amount recognized in Cost of Goods sold	$ 360	134	$ 109	$ 682	$ 703	1,109	1,469	1,628
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Goodwill		$ 40,686				$ 45,589	45,589	40,686	$ 45,105
Successor [Member] | Merger with Dow [Member]
Business Acquisition [Line Items]
Business Combination, Fair Value Step-Up Of Acquired Inventory, Amount recognized in Cost of Goods sold							1,434	1,563
Business Combination, Fair Value Step-Up Of Acquired Inventory Recognized Including Discontinued Operations							$ 1,538
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Goodwill, Measurement Period Adjustments								$ 392