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, 2015			92			(20)
Balance at Dec. 31, 2015			$ 1	$ 2,197	$ 1,088	$ (1,560)	$ (250)
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 (in shares) at Dec. 31, 2016			84			(28)
Balance at Dec. 31, 2016			$ 1	2,288	1,654	$ (2,077)	(218)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of a change in accounting for share-based payments					5
Net income		1,346			1,346
Foreign currency translation adjustments		67					67
Fixed price diesel swaps		0
Neff acquisition				7
Stock compensation expense, net	[1]			91
Exercise of common stock options				3
Shares repurchased and retired				(28)
Repurchase of common stock (in shares)						0
Repurchase of common stock						$ (28)
Other				(5)
Balance (in shares) at Dec. 31, 2017			84			(28)
Balance at Dec. 31, 2017		3,106	$ 1	2,356	3,005	$ (2,105)	(151)	[2]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		1,096			1,096
Foreign currency translation adjustments		(84)					(84)	[2]
Fixed price diesel swaps		(2)					(2)	[2]
Stock compensation expense, net (in shares)			1
Stock compensation expense, net				102
Exercise of common stock options				2
Shares repurchased and retired				(52)
Repurchase of common stock (in shares)			5			5
Repurchase of common stock						$ (765)
Balance (in shares) at Dec. 31, 2018			80			(33)
Balance at Dec. 31, 2018		$ 3,403	$ 1	$ 2,408	$ 4,101	$ (2,870)	$ (237)	[2]

[1] 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.

[2] As of December 31, 2018, 2017 and 2016, the Accumulated Other Comprehensive Loss balance primarily reflects foreign currency translation adjustments.