Unaudited Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 539	$ 463
Current Assets
Allowance for doubtful accounts - trade receivables	10	9
Trade receivables - third party and affiliates	729	850
Nontrade Receivables, Current	312	331
Accumulated depreciation	3,087	2,957
Property, plant and equipment (net of accumulated depreciation - 2020: $3,087; 2019: $2,957; variable interest entity restricted - 2020: $612; 2019: $622)	3,725	3,713
Other assets	399	338
Intangible assets (variable interest entity restricted - 2020: $22; 2019: $22)	$ 317	$ 312
Stockholders' Equity
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares	51,083,026	49,417,965
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	169,371,322	168,973,172
Common stock, shares outstanding	118,288,296	119,555,207
Variable Interest Entity, Primary Beneficiary [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 33	$ 57
Current Assets
Trade receivables - third party and affiliates	5	6
Property, plant and equipment (net of accumulated depreciation - 2020: $3,087; 2019: $2,957; variable interest entity restricted - 2020: $612; 2019: $622)	612	622
Other assets	15	9
Intangible assets (variable interest entity restricted - 2020: $22; 2019: $22)	$ 22	$ 22