Ventures and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 497	$ 439	$ 703	$ 576
Trade receivables - third party and affiliates		947	1,017
Property, plant and equipment (net of accumulated depreciation - 2019: $161; 2018: $130)		3,585	3,719
Accumulated depreciation		2,848	2,803
Intangible assets (net of accumulated amortization - 2019: $4; 2018: $3)		314	310
Accumulated amortization		593	595
Other assets		344	290
Total assets		9,414	9,313
Trade payables		764	819
Other liabilities		1,533	1,779
Deferred income taxes		269	255
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		46	24
Trade receivables - third party and affiliates		7	6
Property, plant and equipment (net of accumulated depreciation - 2019: $161; 2018: $130)		631	659
Intangible assets (net of accumulated amortization - 2019: $4; 2018: $3)		22	23
Other assets		2	5
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Property, plant and equipment (net of accumulated depreciation - 2019: $161; 2018: $130)		32	42
Trade payables		30	27
Long-term debt		46	58
Total liabilities		91	99
Current installments of long-term debt		15	14
Maximum exposure to loss		119	134
Fairway Methanol LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		46	24
Trade receivables - third party and affiliates		13	11
Property, plant and equipment (net of accumulated depreciation - 2019: $161; 2018: $130)		631	659
Accumulated depreciation		161	130
Intangible assets (net of accumulated amortization - 2019: $4; 2018: $3)		22	23
Accumulated amortization		4	3
Other assets		2	5
Total assets	[1]	714	722
Trade payables		16	16
Other liabilities	[2]	3	4
Long-term debt		4	5
Deferred income taxes		4	3
Total liabilities		$ 27	$ 28

[1] 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.