Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 Locations	Sep. 30, 2011	Sep. 30, 2012 Locations	Sep. 30, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of geographic regions entity operates in (in locations)	12		12
Equipment rentals	$ 1,051	$ 604	$ 2,419	$ 1,562
Sales of rental equipment	101	42	258	115
Sales of new equipment	24	24	64	60
Contractor supplies sales	23	23	64	66
Service and other revenues	20	20	63	62
Total revenues	1,219	713	2,868	1,865
Depreciation and amortization expense	275	123	625	351
Equipment rentals gross profit	452	233	937	510
Capital expenditures			1,185	655
Assets	10,992		10,992		4,143
General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals	971	540	2,227	1,419
Sales of rental equipment	98	40	250	110
Sales of new equipment	22	22	59	54
Contractor supplies sales	21	21	58	61
Service and other revenues	19	20	60	60
Total revenues	1,131	643	2,654	1,704
Depreciation and amortization expense	264	116	592	330
Equipment rentals gross profit	410	198	847	442
Capital expenditures			1,112	595
Assets	10,502		10,502		3,776
Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals	80	64	192	143
Sales of rental equipment	3	2	8	5
Sales of new equipment	2	2	5	6
Contractor supplies sales	2	2	6	5
Service and other revenues	1	0	3	2
Total revenues	88	70	214	161
Depreciation and amortization expense	11	7	33	21
Equipment rentals gross profit	42	35	90	68
Capital expenditures			73	60
Assets	$ 490		$ 490		$ 367