Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information
Equipment rentals	$ 1,179		$ 1,009	$ 2,184		$ 1,925
Sales of rental equipment	138		131	248		254
Sales of new equipment	37		24	63		45
Contractor supplies sales	22		23	41		43
Service and other revenues	23		19	41		39
Total revenues	1,399		1,206	2,577		2,306
Depreciation and amortization expense				576		536
Equipment rentals gross profit	503		402	882		723
Assets	12,467			12,467			11,231
Operating Segments
Segment Reporting Information
Equipment rentals	1,179		1,009	2,184		1,925
Sales of rental equipment	138		131	248		254
Sales of new equipment	37		24	63		45
Contractor supplies sales	22		23	41		43
Service and other revenues	23		19	41		39
Total revenues	1,399		1,206	2,577		2,306
Depreciation and amortization expense	299		270	576		536
Equipment rentals gross profit	503		402	882		723
Capital expenditures				1,080		1,066
Assets	12,467			12,467			11,231
Operating Segments | General rentals
Segment Reporting Information
Number of geographic regions entity operates in (in locations)	12			12
Equipment rentals	1,028		932	1,952		1,786
Sales of rental equipment	132		126	238		245
Sales of new equipment	25		22	49		42
Contractor supplies sales	19		21	36		39
Service and other revenues	17		17	34		36
Total revenues	1,221		1,118	2,309		2,148
Depreciation and amortization expense	263		258	522		510
Equipment rentals gross profit	426		366	770		661
Capital expenditures				981		1,003
Assets	10,979			10,979			10,677
Operating Segments | Trench safety, power and HVAC, and pump solutions
Segment Reporting Information
Equipment rentals	151		77	232		139
Sales of rental equipment	6		5	10		9
Sales of new equipment	12		2	14		3
Contractor supplies sales	3		2	5		4
Service and other revenues	6		2	7		3
Total revenues	178		88	268		158
Depreciation and amortization expense	36		12	54		26
Equipment rentals gross profit	77		36	112		62
Capital expenditures				99		63
Assets	$ 1,488	[1]		$ 1,488	[1]		$ 554	[1]

[1] The increase in the trench safety, power and HVAC, and pump solutions assets primarily reflects the impact of the National Pump acquisition discussed in note 2 to the condensed consolidated financial statements.