Segment Information (Financial information by segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information
Equipment rentals	$ 1,315		$ 1,138	$ 3,499		$ 3,063
Sales of rental equipment	140		102	388		356
Sales of new equipment	42		29	105		74
Contractor supplies sales	23		23	64		66
Service and other revenues	24		19	65		58
Total revenues	1,544		1,311	4,121		3,617
Assets	12,483			12,483			11,231
Operating Segments
Segment Reporting Information
Equipment rentals	1,315		1,138	3,499		3,063
Sales of rental equipment	140		102	388		356
Sales of new equipment	42		29	105		74
Contractor supplies sales	23		23	64		66
Service and other revenues	24		19	65		58
Total revenues	1,544		1,311	4,121		3,617
Depreciation and amortization expense	306		278	882		814
Equipment rentals gross profit	599		497	1,481		1,220
Capital expenditures				1,568		1,570
Assets	12,483			12,483			11,231
Operating Segments | General rentals
Segment Reporting Information
Number of geographic regions entity operates in (in locations)	12			12
Equipment rentals	1,127		1,038	3,079		2,824
Sales of rental equipment	133		98	371		343
Sales of new equipment	31		27	80		69
Contractor supplies sales	19		21	55		60
Service and other revenues	21		18	55		54
Total revenues	1,331		1,202	3,640		3,350
Depreciation and amortization expense	267		261	789		771
Equipment rentals gross profit	496		445	1,266		1,106
Capital expenditures				1,391		1,461
Assets	10,747			10,747			10,677
Operating Segments | Trench safety, power and HVAC, and pump solutions
Segment Reporting Information
Equipment rentals	188		100	420		239
Sales of rental equipment	7		4	17		13
Sales of new equipment	11		2	25		5
Contractor supplies sales	4		2	9		6
Service and other revenues	3		1	10		4
Total revenues	213		109	481		267
Depreciation and amortization expense	39		17	93		43
Equipment rentals gross profit	103		52	215		114
Capital expenditures				177		109
Assets	$ 1,736	[1]		$ 1,736	[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.