Derivatives (Effect of derivatives on consolidated statements of income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012 gal		Jun. 30, 2011 gal		Jun. 30, 2012 gal		Jun. 30, 2011 gal
Derivative Instruments, Gain (Loss) [Line Items]
Threshold for inclusion					1
Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Purchases of diesel covered by the fixed price swaps (in gallons)	1,500,000		1,700,000		2,700,000		2,600,000
Swap [Member] | Designated as hedging instruments [Member] | Cost of equipment rentals excluding depreciation (2), (3) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (expense) recognized on derivative			1	[1],[2]			1	[1],[2]
Amount of income (expese) recognized on hedged item	(6)	[1],[2]	(7)	[1],[2]	(11)	[1],[2]	(10)	[1],[2]
Foreign Exchange Forward [Member] | Not designated as hedging instruments [Member] | Other income (expense), net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (expense) recognized on derivative	(1)				(1)		4
Amount of income (expese) recognized on hedged item	1				1		(4)

[1] Amounts recognized on derivative represent the effective portion of the fixed price diesel swaps.

[2] Amounts recognized on hedged item reflect the use of 1.5 million and 1.7 million gallons of diesel covered by the fixed price swaps during the three months ended June 30, 2012 and 2011, respectively, and the use of 2.7 million and 2.6 million gallons of diesel covered by the fixed price swaps during the six months ended June 30, 2012 and 2011, respectively.