Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents	$ 851	$ 780
Allowance for doubtful accounts - trade receivables	6	9
Accumulated depreciation	1,810	1,816
Property, plant and equipment	3,685	3,733
Other assets	343	377
Finite-Lived Intangible Assets, Accumulated Amortization	517	556
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	13,266,625	13,266,625
Common stock, par value	$ 0.0001
Series A common stock, $0.0001 par value, 400,000,000 shares authorized (2015: 166,517,146 issued and 153,250,521 outstanding; 2014: 166,169,335 issued and 152,902,710 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	166,517,146	166,169,335
Common stock, shares outstanding	153,250,521	156,939,828
Series B common stock, $0.0001 par value, 100,000,000 shares authorized (2015 and 2014: 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	1	1
Property, plant and equipment	620	535
Other assets	$ 29	$ 24