Derivatives (Effect of derivatives on consolidated statements of income) (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014 gal		Jun. 30, 2013 gal		Jun. 30, 2014 gal		Jun. 30, 2013 gal
Derivative Instruments, Gain (Loss) [Line Items]
Threshold for inclusion (less than $1 million)	$ 1,000,000		$ 1,000,000		$ 1,000,000		$ 1,000,000
Purchases of diesel covered by the fixed price swaps (in gallons)	3,000,000		2,100,000		5,600,000		4,300,000
Fixed price swap contracts | Designated as hedging instruments | Cost of equipment rentals, excluding depreciation
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (expense) recognized on derivative		[1],[2],[3]		[1],[2],[3]		[1],[2],[3]		[1],[2],[3]
Amount of income (expense) recognized on hedged item	(12,000,000)	[1],[3]	(8,000,000)	[1],[3]	(22,000,000)	[1],[3]	(17,000,000)	[1],[3]
Fixed price swap contracts | Designated as hedging instruments | Other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (expense) recognized on derivative		[2],[4]		[2],[4]		[2],[4]		[2],[4]
Foreign currency forward contracts | Not designated as hedging instruments | Other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of income (expense) recognized on derivative	0	[5]	(2,000,000)	[5]	0	[5]	(4,000,000)	[5]
Amount of income (expense) recognized on hedged item	$ 0	[5]	$ 2,000,000	[5]	$ 0	[5]	$ 4,000,000	[5]

[1] Amounts recognized on hedged item reflect the use of 3.0 million and 2.1 million gallons of diesel covered by the fixed price swaps during the three months ended June 30, 2014 and 2013, respectively, and the use of 5.6 million and 4.3 million gallons of diesel covered by the fixed price swaps during the six months ended June 30, 2014 and 2013, 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.

[2] Amounts are insignificant (less than $1).

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

[4] Represents the ineffective portion of the fixed price diesel swaps.

[5] 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.