Ventures and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 439	$ 576	$ 638	$ 967
Trade receivables - third party and affiliates		1,017	986
Property, plant and equipment (net of accumulated depreciation - 2018: $130; 2017: $90)		3,719	3,762
Accumulated depreciation		2,803	2,584
Intangible assets, net		310	301
Accumulated amortization		595	591	$ (524)
Other assets		290	338
Total assets		9,313	9,538
Trade payables		819	807
Current liabilities		1,779	1,559
Deferred income taxes		255	211
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		24	19
Trade receivables - third party and affiliates		6	5
Property, plant and equipment (net of accumulated depreciation - 2018: $130; 2017: $90)		659	697
Intangible assets, net		23	25
Other assets		5	6
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Property, plant and equipment (net of accumulated depreciation - 2018: $130; 2017: $90)		42	53
Trade payables		27	25
Current installments of long-term debt		14	18
Long-term debt		57	76
Total liabilities		98	119
Maximum exposure to loss		133	164
Fairway Methanol LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		24	19
Trade receivables - third party and affiliates		11	9
Property, plant and equipment (net of accumulated depreciation - 2018: $130; 2017: $90)		659	697
Accumulated depreciation		130	90
Intangible assets, net		23	25
Accumulated amortization		3	2
Other assets		5	6
Total assets	[1]	722	756
Trade payables		16	16
Current liabilities	[2]	4	4
Long-term debt		5	5
Deferred income taxes		3	3
Total liabilities		$ 28	$ 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.