CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED) - 3 months ended Mar. 31, 2017 - 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, 2016			84	[1]			28
Balance at Dec. 31, 2016		$ 1,648	$ 1		$ 2,288	$ 1,654	$ (2,077)	$ (218)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		109				109
Foreign currency translation adjustments		9						9
Fixed price diesel swaps		(1)						(1)
Stock compensation expense, net (in shares)	[1]		1
Stock compensation expense, net					16
Exercise of common stock options					1
Shares repurchased and retired					(23)
Other					(6)
Balance (in shares) at Mar. 31, 2017			85	[1]			28
Balance at Mar. 31, 2017		$ 1,753	$ 1		$ 2,276	$ 1,763	$ (2,077)	$ (210)

[1] Common stock outstanding decreased by approximately 8 million net shares during the year ended December 31, 2016.

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