Ventures and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 615	$ 463	$ 497	$ 439
Trade receivables - third party and affiliates		716	850
Non-trade receivables, net (variable interest entity restricted - 2020: $7; 2019: $0)		347	331
Property, plant and equipment (net of accumulated depreciation - 2020: $201; 2019: $174)		3,851	3,713
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		3,201	2,957
Intangible assets (net of accumulated amortization - 2020: $5; 2019: $4)		317	312
Finite-Lived Intangible Assets, Accumulated Amortization		646	612
Other assets		412	338
Total assets		9,769	9,476
Trade payables		699	780
Other liabilities		2,409	1,754
Total debt		201	144
Deferred income taxes		164	257
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Trade receivables - third party and affiliates		6	6
Variable Interest Entity, Primary Beneficiary [Member] | Fairway Methanol LLC [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		29	57
Trade receivables - third party and affiliates		11	12
Non-trade receivables, net (variable interest entity restricted - 2020: $7; 2019: $0)		7	0
Property, plant and equipment (net of accumulated depreciation - 2020: $201; 2019: $174)		602	622
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		201	174
Intangible assets (net of accumulated amortization - 2020: $5; 2019: $4)		21	22
Finite-Lived Intangible Assets, Accumulated Amortization		5	4
Other assets		14	9
Total assets	[1]	684	722
Trade payables		13	24
Other liabilities	[2]	10	5
Total debt		3	4
Deferred income taxes		4	4
Total liabilities		30	37
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Property, plant and equipment (net of accumulated depreciation - 2020: $201; 2019: $174)		100	31
Trade payables		27	30
Finance Lease, Liability		104	41
Total liabilities		149	87
Current installments of long-term debt		18	16
Maximum exposure to loss		$ 262	$ 113

[1] Joint venture assets can only be used to settle the obligations of Fairway.

[2] Primarily represents amounts owed by Fairway to the Company for reimbursement of expenditures.