Segment Information (Financial information by segment) (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
Segment Reporting Information [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
Depreciation and amortization									2,038	1,671	1,383
Equipment rentals gross profit	965	$ 1,033	$ 911	$ 761	998	$ 938	$ 782	$ 646	3,670	3,364	2,769
Capital expenditures									2,350	2,291	1,889
Total assets	18,970				18,133				18,970	18,133	15,030
Equipment rentals
Segment Reporting Information [Line Items]
Revenues									7,964	6,940	5,715
Revenue from contract with customer, excluding assessed tax									7,964	6,940	5,715
Sales of rental equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									831	664	550
Sales of new equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									268	208	178
Contractor supplies sales
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									104	91	80
Service and other revenues
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									184	144	118
Equipment rentals operating lease
Segment Reporting Information [Line Items]
Equipment rentals gross profit									3,207	2,963	2,440
General rentals
Segment Reporting Information [Line Items]
Revenues									7,436	6,550	5,565
Depreciation and amortization									1,681	1,410	1,188
Capital expenditures									1,967	1,980	1,675
Total assets	16,036				15,597				16,036	15,597	13,351
General rentals | Equipment rentals
Segment Reporting Information [Line Items]
Revenues									6,202	5,550	4,727
General rentals | Sales of rental equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									768	619	509
General rentals | Sales of new equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									238	186	159
General rentals | Contractor supplies sales
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									71	68	65
General rentals | Service and other revenues
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									157	127	105
General rentals | Equipment rentals operating lease
Segment Reporting Information [Line Items]
Equipment rentals gross profit									2,407	2,293	1,950
Trench, power and fluid solutions
Segment Reporting Information [Line Items]
Revenues									1,915	1,497	1,076
Depreciation and amortization									357	261	195
Capital expenditures									383	311	214
Total assets	$ 2,934				$ 2,536				2,934	2,536	1,679
Trench, power and fluid solutions | Equipment rentals
Segment Reporting Information [Line Items]
Revenues									1,762	1,390	988
Trench, power and fluid solutions | Sales of rental equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									63	45	41
Trench, power and fluid solutions | Sales of new equipment
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									30	22	19
Trench, power and fluid solutions | Contractor supplies sales
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									33	23	15
Trench, power and fluid solutions | Service and other revenues
Segment Reporting Information [Line Items]
Revenue from contract with customer, excluding assessed tax									27	17	13
Trench, power and fluid solutions | Equipment rentals operating lease
Segment Reporting Information [Line Items]
Equipment rentals gross profit									$ 800	$ 670	$ 490