Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Locations	Mar. 31, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of Geographic Regions Entity Operates In (in locations)	7
Equipment rentals	$ 523	$ 434
Sales of rental equipment	76	32
Sales of new equipment	18	15
Contractor supplies sales	18	21
Service and other revenues	21	21
Total revenues	656	523
Depreciation and amortization expense	129	111
Segment operating income	87	30
Capital expenditures	426	120
Assets	7,297		4,143
General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals	475	400
Sales of rental equipment	74	30
Sales of new equipment	17	14
Contractor supplies sales	16	20
Service and other revenues	20	20
Total revenues	602	484
Depreciation and amortization expense	119	105
Segment operating income	89	26
Capital expenditures	413	109
Assets	6,871		3,776
Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals	48	34
Sales of rental equipment	2	2
Sales of new equipment	1	1
Contractor supplies sales	2	1
Service and other revenues	1	1
Total revenues	54	39
Depreciation and amortization expense	10	6
Segment operating income	8	5
Capital expenditures	13	11
Assets	426		367
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment operating income	$ 97	$ 31