Segment Information (Geographic area information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Equipment rentals																	$ 4,819		$ 4,196		$ 3,455
Sales of rental equipment																	544		490		399
Sales of new equipment																	149		104		93
Contractor supplies sales																	85		87		87
Service and other revenues																	88		78		83
Total revenues	1,564	[1]	1,544	[1]	1,399	[1]	1,178	[1]	1,338	[2]	1,311	[2]	1,206	[2]	1,100	[2]	5,685	[1]	4,955	[2]	4,117
Goodwill, net	4,378								3,971								4,378		3,971
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Equipment rentals																	4,217		3,612		2,948
Sales of rental equipment																	478		438		350
Sales of new equipment																	124		82		67
Contractor supplies sales																	70		70		67
Service and other revenues																	73		62		66
Total revenues																	4,962		4,264		3,498
Goodwill, net	4,014								3,639								4,014		3,639
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Equipment rentals																	602		584		507
Sales of rental equipment																	66		52		49
Sales of new equipment																	25		22		26
Contractor supplies sales																	15		17		20
Service and other revenues																	15		16		17
Total revenues																	723		691		619
Goodwill, net	364								332								364		332
Rental equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	6,008								5,374								6,008		5,374
Rental equipment, net | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	5,399								4,768								5,399		4,768
Rental equipment, net | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	609								606								609		606
Property and equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	438								421								438		421
Property and equipment, net | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	395								381								395		381
Property and equipment, net | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 43								$ 40								$ 43		$ 40

[1] The fourth quarter of 2014 includes an increase in bad debt expense of $8 as compared to the fourth quarter of 2013 primarily due to improved receivable aging which reduced the expense in the fourth quarter of 2013. Additionally, the fourth quarter of 2014 includes an increase in stock compensation, net of $14 as compared to the fourth quarter of 2013 primarily due to improved profitability which resulted in increased performance based stock compensation.

[2] The fourth quarter of 2013 includes a reduction in bad debt expense of $17 as compared to the fourth quarter of 2012 primarily due to improved receivable aging. In the fourth quarter of 2013, we recognized a benefit of $3 in cost of equipment rentals, excluding depreciation related to our provision for self-insurance reserves.