Derivatives (Effect of derivatives on consolidated statements of income) (Details) gal in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015 USD ($) gal	Jun. 30, 2014 USD ($) gal	Jun. 30, 2015 USD ($) gal	Jun. 30, 2014 USD ($) gal
Derivative Instruments, Gain (Loss) [Line Items]
Purchases of diesel covered by the fixed price swaps (in gallons) | gal		2.8	3.0	5.4	5.6
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]	$ (1)		$ (3)
Amount of income (expense) recognized on hedged item	[1],[2]	$ (9)	$ (12)	$ (16)	$ (22)

[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 2.8 million and 3.0 million gallons of diesel covered by the fixed price swaps during the three months ended June 30, 2015 and 2014, respectively, and the use of 5.4 million and 5.6 million gallons of diesel covered by the fixed price swaps during the six months ended June 30, 2015 and 2014, respectively. These amounts are reflected, net of cash received from, or paid to, the counterparties to the fixed price swaps, in operating cash flows in our condensed consolidated statement of cash flows.