Derivatives (Effect of derivatives on consolidated statements of income) (Details) gal in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) gal	Jun. 30, 2015 USD ($) gal	Jun. 30, 2016 USD ($) gal	Jun. 30, 2015 USD ($) gal
Fixed price swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Purchases of diesel covered by the fixed price swaps (in gallons) | gal	2.4	2.8	5.0	5.4
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	$ (2)	$ (1)	$ (4)	$ (3)
Amount of income (expense) recognized on hedged item	(6)	(9)	(11)	(16)
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	3	0	3	0
Amount of income (expense) recognized on hedged item	$ (3)	$ 0	$ (3)	$ 0