Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Current Assets
Allowance for doubtful accounts - trade receivables	$ 6	$ 6
Accumulated depreciation	2,239	2,039
Cash and cash equivalents (variable interest entity restricted - 2016: $18; 2015: $7)	638	967
Trade receivables - third party and affiliates	801	706
Property, plant and equipment (net of accumulated depreciation - 2016: $2,239; 2015: $2,039; variable interest entity restricted - 2016: $734; 2015: $772)	3,577	3,609
Other assets (variable interest entity restricted - 2016: $9; 2015: $13)	307	300
Intangible assets, net (variable interest entity restricted - 2016: $26; 2015: $27)	$ 194	$ 125
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	26,950,910	19,916,490
Common stock, par value	$ 0.0001
Series A common stock, $0.0001 par value, 400,000,000 shares authorized (2016: 167,611,357 issued and 140,660,447 outstanding; 2015: 166,698,787 issued and 146,782,297 outstanding)
Stockholders' Equity
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	167,611,357	166,698,787
Common stock, shares outstanding	140,660,447	146,782,297
Series B common stock, $0.0001 par value, 100,000,000 shares authorized (2016 and 2015: 0 issued and outstanding)
Stockholders' Equity
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents (variable interest entity restricted - 2016: $18; 2015: $7)	$ 18	$ 7
Trade receivables - third party and affiliates	4	6
Property, plant and equipment (net of accumulated depreciation - 2016: $2,239; 2015: $2,039; variable interest entity restricted - 2016: $734; 2015: $772)	734	772
Other assets (variable interest entity restricted - 2016: $9; 2015: $13)	9	13
Intangible assets, net (variable interest entity restricted - 2016: $26; 2015: $27)	$ 26	$ 27