CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions		Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2014			98			(10)
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				1
4 percent Convertible Senior Notes (in shares)	[1]		4
4 percent Convertible Senior Notes	[1]			5
Shares repurchased and retired				(31)
Repurchase of common stock (in shares)			(10)			10
Repurchase of common stock						$ (758)
Excess tax benefits from share-based payment arrangements, net				5
Balance at Dec. 31, 2015			$ 1	2,197	1,088	$ (1,560)	(250)
Balance (in shares) at Dec. 31, 2015			92			(20)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		566			566
Foreign currency translation adjustments		28					28
Fixed price diesel swaps		4					4
Stock compensation expense, net				45
Exercise of common stock options				1
Shares repurchased and retired				(11)
Repurchase of common stock (in shares)			(8)			8
Repurchase of common stock						$ (517)
Excess tax benefits from share-based payment arrangements, net				56
Balance at Dec. 31, 2016		1,648	$ 1	2,288	1,654	$ (2,077)	(218)	[2]
Balance (in shares) at Dec. 31, 2016			84			(28)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of a change in accounting for share-based payments (note 2)					5
Net income		1,346			1,346
Foreign currency translation adjustments		67					67	[2]
Fixed price diesel swaps		0
Neff acquisition (note 3)				7
Stock compensation expense, net	[3]			91
Exercise of common stock options				3
Shares repurchased and retired				(28)
Repurchase of common stock						$ (28)
Other				(5)
Balance at Dec. 31, 2017		$ 3,106	$ 1	$ 2,356	$ 3,005	$ (2,105)	$ (151)	[2]
Balance (in shares) at Dec. 31, 2017			84			(28)

[1] 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.

[2] As of December 31, 2017, 2016 and 2015, the Accumulated Other Comprehensive Loss balance primarily reflects foreign currency translation adjustments.

[3] Includes net stock compensation expense as reported as a separate component in our consolidated statements of cash flows, and net stock compensation expense included in “Restructuring charge” as reported in our consolidated statements of cash flows.