Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Locations	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting, Measurement Disclosures [Abstract]
Number of geographic regions entity operates in (in locations)	12
Segment Reporting Information [Line Items]
Equipment rentals	$ 916	$ 523
Sales of rental equipment	123	76
Sales of new equipment	21	18
Contractor supplies sales	20	18
Service and other revenues	20	21
Total revenues	1,100	656
Depreciation and amortization expense	266	129
Equipment rentals gross profit	321	162
Capital expenditures	303	426
Assets	10,921		11,026
General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals	854	475
Sales of rental equipment	119	74
Sales of new equipment	20	17
Contractor supplies sales	18	16
Service and other revenues	19	20
Total revenues	1,030	602
Depreciation and amortization expense	252	119
Equipment rentals gross profit	295	144
Capital expenditures	288	413
Assets	10,448		10,545
Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals	62	48
Sales of rental equipment	4	2
Sales of new equipment	1	1
Contractor supplies sales	2	2
Service and other revenues	1	1
Total revenues	70	54
Depreciation and amortization expense	14	10
Equipment rentals gross profit	26	18
Capital expenditures	15	13
Assets	$ 473		$ 481