Segment Information (Geographic Area information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 2,456	$ 2,488	$ 2,290	$ 2,117	$ 2,306	$ 2,116	$ 1,891	$ 1,734	$ 9,351	$ 8,047	$ 6,641
Rental equipment, net	9,787				9,600				9,787	9,600
Property and equipment, net	604				614				604	614
Goodwill and other intangible assets, net	6,049				6,142				6,049	6,142
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									8,534	7,387	6,076
Rental equipment, net	8,995				8,910				8,995	8,910
Property and equipment, net	554				559				554	559
Goodwill and other intangible assets, net	5,592				5,665				5,592	5,665
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									817	660	565
Rental equipment, net	792				690				792	690
Property and equipment, net	50				55				50	55
Goodwill and other intangible assets, net	$ 457				$ 477				457	477
Total equipment rentals
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									7,964	6,940	5,715
Revenues									7,964	6,940	5,715
Total equipment rentals | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									7,283	6,388	5,253
Total equipment rentals | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									681	552	462
Sales of rental equipment
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									831	664	550
Sales of rental equipment | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									757	609	494
Sales of rental equipment | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									74	55	56
Sales of new equipment
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									268	208	178
Sales of new equipment | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									238	184	157
Sales of new equipment | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									30	24	21
Contractor supplies sales
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									104	91	80
Contractor supplies sales | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									92	80	70
Contractor supplies sales | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									12	11	10
Service and other revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									184	144	118
Service and other revenues | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									164	126	102
Service and other revenues | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									$ 20	$ 18	$ 16