Segment Information (Financial information by segment) (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
Segment Reporting Information [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
Depreciation and amortization									1,988	2,038	1,671
Equipment rentals gross profit	869	$ 886	$ 701	$ 727	965	$ 1,033	$ 911	$ 761	3,183	3,670	3,364
Capital expenditures									1,158	2,350	2,291
Total assets	17,868				18,970				17,868	18,970	18,133
Equipment rentals
Segment Reporting Information [Line Items]
Revenues									7,140	7,964	6,940
Sales of rental equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									858	831	664
Sales of new equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									247	268	208
Contractor supplies sales
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									98	104	91
Service and other revenues
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									187	184	144
Equipment rentals gross profit
Segment Reporting Information [Line Items]
Equipment rentals gross profit									2,719	3,207	2,963
General rentals
Segment Reporting Information [Line Items]
Revenues									6,699	7,436	6,550
Depreciation and amortization									1,633	1,681	1,410
Capital expenditures									969	1,967	1,980
Total assets	15,051				16,036				15,051	16,036	15,597
General rentals | Equipment rentals
Segment Reporting Information [Line Items]
Revenues									5,472	6,202	5,550
General rentals | Sales of rental equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									785	768	619
General rentals | Sales of new equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									214	238	186
General rentals | Contractor supplies sales
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									64	71	68
General rentals | Service and other revenues
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									164	157	127
General rentals | Equipment rentals gross profit
Segment Reporting Information [Line Items]
Equipment rentals gross profit									1,954	2,407	2,293
Trench, power and fluid solutions
Segment Reporting Information [Line Items]
Revenues									1,831	1,915	1,497
Depreciation and amortization									355	357	261
Capital expenditures									189	383	311
Total assets	$ 2,817				$ 2,934				2,817	2,934	2,536
Trench, power and fluid solutions | Equipment rentals
Segment Reporting Information [Line Items]
Revenues									1,668	1,762	1,390
Trench, power and fluid solutions | Sales of rental equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									73	63	45
Trench, power and fluid solutions | Sales of new equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									33	30	22
Trench, power and fluid solutions | Contractor supplies sales
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									34	33	23
Trench, power and fluid solutions | Service and other revenues
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									23	27	17
Trench, power and fluid solutions | Equipment rentals gross profit
Segment Reporting Information [Line Items]
Equipment rentals gross profit									$ 765	$ 800	$ 670