Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information
Equipment rentals	$ 1,005	$ 916
Sales of rental equipment	110	123
Sales of new equipment	26	21
Contractor supplies sales	19	20
Service and other revenues	18	20
Total revenues	1,178	1,100
Depreciation and amortization expense	277	266
Equipment rentals gross profit	379	321
Assets	11,247		11,231
Operating Segments
Segment Reporting Information
Equipment rentals	1,005	916
Sales of rental equipment	110	123
Sales of new equipment	26	21
Contractor supplies sales	19	20
Service and other revenues	18	20
Total revenues	1,178	1,100
Depreciation and amortization expense	277	266
Equipment rentals gross profit	379	321
Capital expenditures	351	303
Assets	11,247		11,231
Operating Segments | General rentals
Segment Reporting Information
Number of geographic regions entity operates in (in locations)	12
Equipment rentals	924	854
Sales of rental equipment	106	119
Sales of new equipment	24	20
Contractor supplies sales	17	18
Service and other revenues	17	19
Total revenues	1,088	1,030
Depreciation and amortization expense	259	252
Equipment rentals gross profit	344	295
Capital expenditures	331	288
Assets	10,696		10,677
Operating Segments | Trench safety, power and HVAC
Segment Reporting Information
Equipment rentals	81	62
Sales of rental equipment	4	4
Sales of new equipment	2	1
Contractor supplies sales	2	2
Service and other revenues	1	1
Total revenues	90	70
Depreciation and amortization expense	18	14
Equipment rentals gross profit	35	26
Capital expenditures	20	15
Assets	$ 551		$ 554