CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED) - 3 months ended Mar. 31, 2016 - 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, 2015		92	[1]			20
Balance at Dec. 31, 2015	$ 1,476	$ 1		$ 2,197	$ 1,088	$ (1,560)	$ (250)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	92				92
Foreign currency translation adjustments	62						62
Fixed price diesel swaps	1						1
Stock compensation expense, net				9
Shares repurchased and retired				(10)
Repurchase of common stock (in shares)		(3)	[1]			3
Repurchase of common stock						$ (154)
Excess tax benefits from share-based payment arrangements, net				25
Balance (in shares) at Mar. 31, 2016		89	[1]			23
Balance at Mar. 31, 2016	$ 1,501	$ 1		$ 2,221	$ 1,180	$ (1,714)	$ (187)

[1] Common stock outstanding decreased by approximately 6 million net shares during the year ended December 31, 2015.

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