Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 Locations	Jun. 30, 2012	Jun. 30, 2013 Locations	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting, Measurement Disclosures [Abstract]
Number of geographic regions entity operates in (in locations)	12		12
Segment Reporting Information [Line Items]
Equipment rentals	$ 1,009	$ 845	$ 1,925	$ 1,368
Sales of rental equipment	131	81	254	157
Sales of new equipment	24	22	45	40
Contractor supplies sales	23	23	43	41
Service and other revenues	19	22	39	43
Total revenues	1,206	993	2,306	1,649
Depreciation and amortization expense	270	221	536	350
Equipment rentals gross profit	402	323	723	485
Capital expenditures			1,066	898
Assets	11,326		11,326		11,026
General Rentals [Member]
Segment Reporting Information [Line Items]
Equipment rentals	932	781	1,786	1,256
Sales of rental equipment	126	78	245	152
Sales of new equipment	22	20	42	37
Contractor supplies sales	21	21	39	37
Service and other revenues	17	21	36	41
Total revenues	1,118	921	2,148	1,523
Depreciation and amortization expense	258	209	510	328
Equipment rentals gross profit	366	293	661	437
Capital expenditures			1,003	853
Assets	10,811		10,811		10,545
Trench Safety, Power and HVAC [Member]
Segment Reporting Information [Line Items]
Equipment rentals	77	64	139	112
Sales of rental equipment	5	3	9	5
Sales of new equipment	2	2	3	3
Contractor supplies sales	2	2	4	4
Service and other revenues	2	1	3	2
Total revenues	88	72	158	126
Depreciation and amortization expense	12	12	26	22
Equipment rentals gross profit	36	30	62	48
Capital expenditures			63	45
Assets	$ 515		$ 515		$ 481