Segment Information (Financial Information by Segment) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) region	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information
Equipment rentals	$ 1,459	$ 1,166
Service and other revenues	34	27
Total revenues	1,734	1,356
Depreciation and amortization expense	393	310
Gross profit	646	514
Capital expenditures	313	241
Assets	14,688		$ 15,030
Rental equipment
Segment Reporting Information
Sales revenue	181	106
New equipment
Segment Reporting Information
Sales revenue	42	39
Contractor supplies
Segment Reporting Information
Sales revenue	18	18
Equipment rentals under operating lease
Segment Reporting Information
Gross profit	$ 545	444
General rentals
Segment Reporting Information
Number of geographic regions entity operates in (locations) | region	11
Equipment rentals	$ 1,201	977
Service and other revenues	30	24
Total revenues	1,453	1,146
Depreciation and amortization expense	337	264
Capital expenditures	267	211
Assets	13,032		13,351
General rentals | Rental equipment
Segment Reporting Information
Sales revenue	171	96
General rentals | New equipment
Segment Reporting Information
Sales revenue	37	35
General rentals | Contractor supplies
Segment Reporting Information
Sales revenue	14	14
General rentals | Equipment rentals under operating lease
Segment Reporting Information
Gross profit	426	360
Trench, power and pump
Segment Reporting Information
Equipment rentals	258	189
Service and other revenues	4	3
Total revenues	281	210
Depreciation and amortization expense	56	46
Capital expenditures	46	30
Assets	1,656		$ 1,679
Trench, power and pump | Rental equipment
Segment Reporting Information
Sales revenue	10	10
Trench, power and pump | New equipment
Segment Reporting Information
Sales revenue	5	4
Trench, power and pump | Contractor supplies
Segment Reporting Information
Sales revenue	4	4
Trench, power and pump | Equipment rentals under operating lease
Segment Reporting Information
Gross profit	$ 119	$ 84