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Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Revenue Recognition (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Owned equipment rentals	$ 1,668	$ 1,406	$ 3,198	$ 2,671
Re-rent revenue	37	29	72	54
Ancillary and other rental revenues:
Revenues	2,290	1,891	4,407	3,625
Topic 842
Revenues:
Owned equipment rentals	1,668		3,198
Re-rent revenue	37		72
Ancillary and other rental revenues:
Revenues	1,792		3,437
Topic 840
Revenues:
Owned equipment rentals		1,406		2,671
Re-rent revenue		29		54
Ancillary and other rental revenues:
Revenues		1,499		2,845
Topic 606
Ancillary and other rental revenues:
Revenues	498	392	970	780
Ancillary and Other Rental Revenues
Revenues:
Revenue from contract with customer	143	112	262	204
Ancillary and other rental revenues:
Other Income	112	84	223	161
Revenues	255	196	485	365
Ancillary and Other Rental Revenues \| Topic 842
Revenues:
Revenue from contract with customer	0		0
Ancillary and other rental revenues:
Other Income	87		167
Revenues	87		167
Ancillary and Other Rental Revenues \| Topic 840
Revenues:
Revenue from contract with customer		0		0
Ancillary and other rental revenues:
Other Income		64		120
Revenues		64		120
Ancillary and Other Rental Revenues \| Topic 606
Revenues:
Revenue from contract with customer	143	112	262	204
Ancillary and other rental revenues:
Other Income	25	20	56	41
Revenues	168	132	318	245
Equipment rentals
Ancillary and other rental revenues:
Revenues	1,960	1,631	3,755	3,090
Equipment rentals \| Topic 842
Ancillary and other rental revenues:
Revenues	1,792		3,437
Equipment rentals \| Topic 840
Ancillary and other rental revenues:
Revenues		1,499		2,845
Equipment rentals \| Topic 606
Ancillary and other rental revenues:
Revenues	168	132	318	245
Sales of rental equipment
Revenues:
Revenue from contract with customer	197	157	389	338
Sales of rental equipment \| Topic 606
Revenues:
Revenue from contract with customer	197	157	389	338
Sales of new equipment
Revenues:
Revenue from contract with customer	60	44	122	86
Sales of new equipment \| Topic 606
Revenues:
Revenue from contract with customer	60	44	122	86
Contractor supplies sales
Revenues:
Revenue from contract with customer	27	24	51	42
Contractor supplies sales \| Topic 606
Revenues:
Revenue from contract with customer	27	24	51	42
Service and other revenues
Revenues:
Revenue from contract with customer	46	35	90	69
Service and other revenues \| Topic 606
Revenues:
Revenue from contract with customer	$ 46	$ 35	$ 90	$ 69