Segment Information (Financial information by segment) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) location	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) location	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information
Equipment rentals	$ 1,322	$ 1,326	$ 3,643	$ 3,671
Sales of rental equipment	112	141	361	381
Sales of new equipment	30	38	96	110
Contractor supplies sales	19	21	60	60
Service and other revenues	25	24	79	72
Total revenues	1,508	1,550	4,239	4,294
Depreciation and amortization expense	311	315	927	926
Gross profit	656	690	1,746	1,832
Capital expenditures			1,210	1,501
Assets	$ 12,275		$ 12,275		$ 12,083
General rentals
Segment Reporting Information
Number of geographic regions entity operates in (locations) | location	9		9
Equipment rentals	$ 1,097	1,120	$ 3,067	3,144
Sales of rental equipment	103	132	334	356
Sales of new equipment	27	33	84	94
Contractor supplies sales	16	18	49	51
Service and other revenues	23	23	71	65
Total revenues	1,266	1,326	3,605	3,710
Depreciation and amortization expense	266	272	791	798
Capital expenditures			1,086	1,325
Assets	10,731		10,731		10,561
Trench, power and pump
Segment Reporting Information
Equipment rentals	225	206	576	527
Sales of rental equipment	9	9	27	25
Sales of new equipment	3	5	12	16
Contractor supplies sales	3	3	11	9
Service and other revenues	2	1	8	7
Total revenues	242	224	634	584
Depreciation and amortization expense	45	43	136	128
Capital expenditures			124	176
Assets	1,544		1,544		$ 1,522
Equipment rentals
Segment Reporting Information
Gross profit	586	607	1,517	1,588
Equipment rentals | General rentals
Segment Reporting Information
Gross profit	469	500	1,243	1,339
Equipment rentals | Trench, power and pump
Segment Reporting Information
Gross profit	$ 117	$ 107	$ 274	$ 249