Segment Information (Financial information by segment) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) location	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) location	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information
Equipment rentals	$ 1,220	$ 1,179	$ 2,345	$ 2,184
Sales of rental equipment	124	138	240	248
Sales of new equipment	39	37	72	63
Contractor supplies sales	21	22	39	41
Service and other revenues	25	23	48	41
Total revenues	1,429	1,399	2,744	2,577
Gross profit	618	589	1,142	1,037
Assets	12,605		12,605		$ 12,467
Operating Segments
Segment Reporting Information
Equipment rentals	1,220	1,179	2,345	2,184
Sales of rental equipment	124	138	240	248
Sales of new equipment	39	37	72	63
Contractor supplies sales	21	22	39	41
Service and other revenues	25	23	48	41
Total revenues	1,429	1,399	2,744	2,577
Depreciation and amortization expense	307	299	611	576
Capital expenditures			1,066	1,080
Assets	$ 12,605		$ 12,605		12,467
Operating Segments | General rentals
Segment Reporting Information
Number of geographic regions entity operates in (locations) | location	11		11
Equipment rentals	$ 1,048	1,028	$ 2,024	1,952
Sales of rental equipment	116	132	224	238
Sales of new equipment	35	25	61	49
Contractor supplies sales	18	19	33	36
Service and other revenues	23	17	42	34
Total revenues	1,240	1,221	2,384	2,309
Depreciation and amortization expense	264	263	526	522
Capital expenditures			949	981
Assets	11,053		11,053		10,935
Operating Segments | Trench, power and pump
Segment Reporting Information
Equipment rentals	172	151	321	232
Sales of rental equipment	8	6	16	10
Sales of new equipment	4	12	11	14
Contractor supplies sales	3	3	6	5
Service and other revenues	2	6	6	7
Total revenues	189	178	360	268
Depreciation and amortization expense	43	36	85	54
Capital expenditures			117	99
Assets	1,552		1,552		$ 1,532
Equipment rentals
Segment Reporting Information
Gross profit	535	503	981	882
Equipment rentals | Operating Segments
Segment Reporting Information
Gross profit	535	503	981	882
Equipment rentals | Operating Segments | General rentals
Segment Reporting Information
Gross profit	456	426	839	770
Equipment rentals | Operating Segments | Trench, power and pump
Segment Reporting Information
Gross profit	$ 79	$ 77	$ 142	$ 112