Ventures and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 539	$ 463	$ 491	$ 439
Trade receivables - third party and affiliates		729	850
Non-trade receivables, net		312	331
Property, plant and equipment (net of accumulated depreciation - 2020: $191; 2019: $174)		3,725	3,713
Accumulated depreciation		3,087	2,957
Intangible assets (net of accumulated amortization - 2020: $4; 2019: $4)		317	312
Accumulated amortization		621	612
Other assets		399	338
Total assets		9,506	9,476
Trade payables		599	780
Other liabilities		2,262	1,754
Total debt		128	144
Deferred income taxes		256	257
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		33	57
Trade receivables - third party and affiliates		5	6
Property, plant and equipment (net of accumulated depreciation - 2020: $191; 2019: $174)		612	622
Intangible assets (net of accumulated amortization - 2020: $4; 2019: $4)		22	22
Other assets		15	9
Variable Interest Entity, Primary Beneficiary [Member] | Fairway Methanol LLC [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		33	57
Trade receivables - third party and affiliates		10	12
Non-trade receivables, net		2	0
Property, plant and equipment (net of accumulated depreciation - 2020: $191; 2019: $174)		612	622
Accumulated depreciation		191	174
Intangible assets (net of accumulated amortization - 2020: $4; 2019: $4)		22	22
Accumulated amortization		4	4
Other assets		15	9
Total assets	[1]	694	722
Trade payables		11	24
Other liabilities	[2]	10	5
Total debt		3	4
Deferred income taxes		4	4
Total liabilities		28	37
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Property, plant and equipment (net of accumulated depreciation - 2020: $191; 2019: $174)		25	31
Trade payables		22	30
Finance Lease, Liability		33	41
Total liabilities		72	87
Current installments of long-term debt		17	16
Maximum exposure to loss		$ 93	$ 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.