Derivatives (Effect of derivatives on consolidated statements of income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Threshold for inclusion (less than $1)	$ 1		$ 1		$ 1		$ 1
Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Purchases of diesel covered by the fixed price swaps (in gallons)	2,700,000		1,800,000		7,000,000		4,500,000
Swap [Member] | Designated as hedging instruments [Member] | Cost of equipment rentals excluding depreciation [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (expense) recognized on hedged item	(11)	[1],[2]	(7)	[1],[2]	(28)	[1],[2]	(18)	[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	2	[3]			(2)	[3]
Amount of income (expense) recognized on hedged item	$ (2)	[3]			$ 2	[3]

[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 2.7 million and 1.8 million gallons of diesel covered by the fixed price swaps during the three months ended September 30, 2013 and 2012, respectively, and the use of 7.0 million and 4.5 million gallons of diesel covered by the fixed price swaps during the nine months ended September 30, 2013 and 2012, respectively. These amounts are reflected, net of cash received from the counterparties to the fixed price swaps, in operating cash flows in our condensed consolidated statement of cash flows.

[3] Insignificant amounts were reflected in our condensed consolidated statement of cash flows associated with the forward contracts to purchase Canadian dollars, as the cash impact of the gains/losses recognized on the derivatives were offset by the gains/losses recognized on the hedged items.