Segment Information (Geographic Area information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 2,279	$ 2,187	$ 1,939	$ 2,125	$ 2,456	$ 2,488	$ 2,290	$ 2,117	$ 8,530	$ 9,351	$ 8,047
Goodwill and other intangible assets, net	5,816				6,049				5,816	6,049
Rental equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	8,705				9,787				8,705	9,787
Property and equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	604				604				604	604
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									7,797	8,534	7,387
Goodwill and other intangible assets, net	5,361				5,592				5,361	5,592
Domestic  | Rental equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	7,960				8,995				7,960	8,995
Domestic  | Property and equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	558				554				558	554
Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									733	817	660
Goodwill and other intangible assets, net	455				457				455	457
Foreign | Rental equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	745				792				745	792
Foreign | Property and equipment, net
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 46				$ 50				46	50
Total equipment rentals
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									7,140	7,964	6,940
Total equipment rentals | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									6,543	7,283	6,388
Total equipment rentals | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									597	681	552
Sales of rental equipment
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									858	831	664
Sales of rental equipment | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									784	757	609
Sales of rental equipment | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									74	74	55
Sales of new equipment
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									247	268	208
Sales of new equipment | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									218	238	184
Sales of new equipment | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									29	30	24
Contractor supplies sales
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									98	104	91
Contractor supplies sales | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									86	92	80
Contractor supplies sales | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									12	12	11
Service and other revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									187	184	144
Service and other revenues | Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									166	164	126
Service and other revenues | Foreign
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue from contract with customer, excluding assessed tax									$ 21	$ 20	$ 18