CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED) - 9 months ended Sep. 30, 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	413				413
Foreign currency translation adjustments	51						51
Fixed price diesel swaps	3						3
Stock compensation expense, net				33
Shares repurchased and retired				(11)
Repurchase of common stock (in shares)		(7)	[1]			7
Repurchase of common stock						$ (477)
Excess tax benefits from share-based payment arrangements, net				51
Balance (in shares) at Sep. 30, 2016		85	[1]			27
Balance at Sep. 30, 2016	$ 1,539	$ 1		$ 2,270	$ 1,501	$ (2,037)	$ (196)

[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.