Segment Information (Financial information by segment) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) location	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) location	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information
Equipment rentals	$ 1,204	$ 1,220	$ 2,321	$ 2,345
Sales of rental equipment	134	124	249	240
Sales of new equipment	36	39	66	72
Contractor supplies sales	22	21	41	39
Service and other revenues	25	25	54	48
Total revenues	1,421	1,429	2,731	2,744
Gross profit	590	618	1,090	1,142
Assets	12,120		12,120		$ 12,083
Operating Segments
Segment Reporting Information
Equipment rentals	1,204	1,220	2,321	2,345
Sales of rental equipment	134	124	249	240
Sales of new equipment	36	39	66	72
Contractor supplies sales	22	21	41	39
Service and other revenues	25	25	54	48
Total revenues	1,421	1,429	2,731	2,744
Depreciation and amortization expense	306	307	616	611
Capital expenditures			764	1,066
Assets	$ 12,120		$ 12,120		12,083
Operating Segments | General rentals
Segment Reporting Information
Number of geographic regions entity operates in (locations) | location	9		9
Equipment rentals	$ 1,015	1,048	$ 1,970	2,024
Sales of rental equipment	125	116	231	224
Sales of new equipment	31	35	57	61
Contractor supplies sales	17	18	33	33
Service and other revenues	22	23	48	42
Total revenues	1,210	1,240	2,339	2,384
Depreciation and amortization expense	259	264	525	526
Capital expenditures			692	949
Assets	10,594		10,594		10,561
Operating Segments | Trench, power and pump
Segment Reporting Information
Equipment rentals	189	172	351	321
Sales of rental equipment	9	8	18	16
Sales of new equipment	5	4	9	11
Contractor supplies sales	5	3	8	6
Service and other revenues	3	2	6	6
Total revenues	211	189	392	360
Depreciation and amortization expense	47	43	91	85
Capital expenditures			72	117
Assets	1,526		1,526		$ 1,522
Equipment rentals
Segment Reporting Information
Gross profit	506	535	931	981
Equipment rentals | Operating Segments
Segment Reporting Information
Gross profit	506	535	931	981
Equipment rentals | Operating Segments | General rentals
Segment Reporting Information
Gross profit	417	456	774	839
Equipment rentals | Operating Segments | Trench, power and pump
Segment Reporting Information
Gross profit	$ 89	$ 79	$ 157	$ 142