Derivatives (Effect of derivatives on consolidated statements of income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 gal		Dec. 31, 2011 gal		Dec. 31, 2010 gal
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instrument threshold	1
Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative purchases of underlying commodity (in gallons)	6,300,000		5,900,000		3,600,000
Swap [Member] | Designated as Hedging Instrument [Member] | Cost of equipment rentals, excluding depreciation [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income recognized on derivative			2	[1],[2]
Amount of expense recognized on hedged item	(25)	[1],[2]	(23)	[1],[2]	(11)	[1],[2]
Foreign Exchange Forward [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income recognized on derivative			4		13
Amount of expense recognized 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
Amount of expense recognized 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 6.3 million, 5.9 million and 3.6 million gallons of diesel covered by the fixed price swaps during the years ended December 31, 2012, 2011 and 2010, respectively.