Derivatives (Effect of derivatives on consolidated statements of income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010
Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income recognized on derivative	$ 4		$ 13
Gain (Loss) on Hedged Item	(23)		(11)
Swap [Member] | Designated as Hedging Instrument [Member] | Cost Of Equipment Rentals Excluding Depreciation [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	2	[1],[2]
Gain (Loss) on Hedged Item	(23)	[1],[2]	(11)	[1],[2]
Foreign Exchange Forward [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Hedged Item	(4)		(13)
Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member] | Other Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income recognized on derivative	4		13
Gain (Loss) on Hedged Item	$ (4)		$ (13)

[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 5.9 million and 3.6 million gallons of diesel covered by the fixed price swaps during the years ended December 31, 2011 and 2010, respectively.