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 at Dec. 31, 2012			$ 1	$ 1,997	$ (424)	$ (115)	$ 84
Balance (in shares) at Dec. 31, 2012			93,000			3,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		$ 387			387
Foreign currency translation adjustments		(65)					(65)
Fixed price diesel swaps		$ 0
Stock compensation expense, net				46
Exercise of common stock options (in shares)		484	1,000
Exercise of common stock options				6
Conversion of subordinated convertible securities (in shares)			1,000
Conversion of subordinated convertible debentures				40
4 percent Convertible Senior Notes	[1]			(14)
Shares repurchased and retired				(21)
Repurchase of common stock (in shares)			(2,000)			2,000
Repurchase of common stock						$ (94)
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
Conversion of subordinated convertible securities (in shares)	[2]		10,000
4 percent Convertible Senior Notes	[2]			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		$ 1,796	$ 1	2,168	503	$ (802)	(74)	[3]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		585			585
Foreign currency translation adjustments		(174)					(174)	[3]
Fixed price diesel swaps		$ (2)					(2)	[3]
Stock compensation expense, net				49
Exercise of common stock options (in shares)		87	0
Exercise of common stock options				1
Conversion of subordinated convertible securities (in shares)	[4]		4,000
4 percent Convertible Senior Notes	[4]			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]

[1] 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 a reduction reflecting the excess of the cash transferred upon conversion of a portion of the 4 percent Convertible Senior Notes during the year ended December 31, 2013 over the principal amount of the converted notes, net of cash received from the option counterparties to our convertible note hedges upon the conversion.

[2] Primarily 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 cash received from the option counterparties to our convertible note hedges associated with conversions of a portion of our 4 percent Convertible Senior Notes.

[3] As of December 31, 2015, 2014 and 2013, the Accumulated Other Comprehensive Income (Loss) balance primarily reflects foreign currency translation adjustments.

[4] 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 all outstanding 4 percent Convertible Senior Notes. See note 12 to our consolidated financial statements for additional detail.