Unaudited Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 570	$ 463
Current Assets
Allowance for doubtful accounts - trade receivables	10	9
Trade receivables - third party and affiliates	853	850
Nontrade Receivables, Current	307	331
Accumulated depreciation	3,001	2,957
Property, plant and equipment (net of accumulated depreciation - 2020: $3,001; 2019: $2,957; variable interest entity restricted - 2020: $619; 2019: $622)	3,678	3,713
Other assets	381	338
Intangible assets (variable interest entity restricted - 2020: $22; 2019: $22)	$ 302	$ 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	51,127,396	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	169,356,294	168,973,172
Common stock, shares outstanding	118,228,898	119,555,207
Variable Interest Entity, Primary Beneficiary [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 37	$ 57
Current Assets
Trade receivables - third party and affiliates	4	6
Property, plant and equipment (net of accumulated depreciation - 2020: $3,001; 2019: $2,957; variable interest entity restricted - 2020: $619; 2019: $622)	619	622
Other assets	17	9
Intangible assets (variable interest entity restricted - 2020: $22; 2019: $22)	$ 22	$ 22