CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Millions		Total	Common Stock	Additional Paid-In Capital	(Accumulated Deficit) Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2013			93,000			5,000
Balance at Dec. 31, 2013			$ 1	$ 2,054	$ (37)	$ (209)	$ 19
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		$ 540			540
Foreign currency translation adjustments		(90)					(90)
Fixed price diesel swaps		$ (3)					(3)
Stock compensation expense, net				74
Exercise of common stock options (in shares)		213	0
Exercise of common stock options				2
4 percent Convertible Senior Notes (in shares)	[1]		10,000
4 percent Convertible Senior Notes	[1]			58
Shares repurchased and retired				(20)
Repurchase of common stock (in shares)			(5,000)			5,000
Repurchase of common stock						$ (593)
Balance (in shares) at Dec. 31, 2014			98,000			10,000
Balance at Dec. 31, 2014			$ 1	2,168	503	$ (802)	(74)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		$ 585			585
Foreign currency translation adjustments		(174)					(174)
Fixed price diesel swaps		$ (2)					(2)
Stock compensation expense, net				49
Exercise of common stock options (in shares)		87	0
Exercise of common stock options				1
4 percent Convertible Senior Notes (in shares)	[2]		4,000
4 percent Convertible Senior Notes	[2]			5
Shares repurchased and retired				(31)
Repurchase of common stock (in shares)			(10,000)			10,000
Repurchase of common stock						$ (758)
Excess tax benefits from share-based payment arrangements, net				5
Balance (in shares) at Dec. 31, 2015			92,000			20,000
Balance at Dec. 31, 2015		$ 1,476	$ 1	2,197	1,088	$ (1,560)	(250)	[3]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		566			566
Foreign currency translation adjustments		28					28	[3]
Fixed price diesel swaps		$ 4					4	[3]
Stock compensation expense, net				45
Exercise of common stock options (in shares)		54	0
Exercise of common stock options				1
Shares repurchased and retired				(11)
Repurchase of common stock (in shares)			(8,000)			8,000
Repurchase of common stock						$ (517)
Excess tax benefits from share-based payment arrangements, net				56
Balance (in shares) at Dec. 31, 2016			84,000			28,000
Balance at Dec. 31, 2016		$ 1,648	$ 1	$ 2,288	$ 1,654	$ (2,077)	$ (218)	[3]

[1] Primarily reflects amortization of the original issue discount on our 4 percent Convertible Senior Notes and cash received from the option counterparties to our convertible note hedges associated with conversions of a portion of our 4 percent Convertible Senior Notes. The 4 percent Convertible Senior Notes matured in 2015.

[2] Reflects amortization of the original issue discount on the 4 percent Convertible Senior Notes and the conversion of all outstanding 4 percent Convertible Senior Notes.

[3] As of December 31, 2016, 2015 and 2014, the Accumulated Other Comprehensive Loss balance primarily reflects foreign currency translation adjustments.