CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED) - 6 months ended Jun. 30, 2015 - USD ($) shares in Millions, $ in Millions		Total	Common Stock		Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive (Loss) Income	[2]
Balance (in shares) at Dec. 31, 2014			98	[1]			10
Balance at Dec. 31, 2014		$ 1,796	$ 1		$ 2,168	$ 503	$ (802)	$ (74)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		201				201
Foreign currency translation adjustments		(73)						(73)
Fixed price diesel swaps		1						1
Stock compensation expense, net					25
Exercise of common stock options					1
4 percent Convertible Senior Notes (in shares)	[1],[3]		3
4 percent Convertible Senior Notes	[3]				1
Shares repurchased and retired					(30)
Repurchase of common stock (in shares)			(6)	[1]			6
Repurchase of common stock							$ (471)
Balance (in shares) at Jun. 30, 2015			95	[1]			16
Balance at Jun. 30, 2015		$ 1,451	$ 1		$ 2,165	$ 704	$ (1,273)	$ (146)

[1] An aggregate of less than 5 million net shares were issued during the year ended December 31, 2014.

[2] The Accumulated Other Comprehensive Loss balance primarily reflects foreign currency translation adjustments.

[3] Reflects amortization of the original issue discount on the 4 percent Convertible Senior Notes (an amount equal to the unamortized portion of the original issue discount is reflected as “temporary equity” in our consolidated balance sheet) and the conversion of a portion of the 4 percent Convertible Senior Notes during the six months ended June 30, 2015. See note 7 to our condensed consolidated financial statements for additional detail.