Segment Information (Financial Information by Segment) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) region	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) region	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information
Revenues	$ 2,596	$ 2,187	$ 6,940	$ 6,251
Revenue from contract with customer	523	490	1,572	1,406
Depreciation and amortization expense	510	492	1,451	1,508
Equipment rentals gross profit	1,103	886	2,692	2,314
Capital expenditures			2,450	930
Assets	20,306		20,306		$ 17,868
Equipment rentals
Segment Reporting Information
Revenues	2,277	1,861	5,895	5,286
Revenue from contract with customer	204	164	527	441
Sales of rental equipment
Segment Reporting Information
Revenues	183	199	644	583
Revenue from contract with customer	183	199	644	583
Sales of new equipment
Segment Reporting Information
Revenues	47	54	153	169
Revenue from contract with customer	47	54	153	169
Contractor supplies sales
Segment Reporting Information
Revenues	29	25	80	73
Revenue from contract with customer	29	25	80	73
Service and other revenues
Segment Reporting Information
Revenues	60	48	168	140
Revenue from contract with customer	60	48	168	140
Equipment rentals gross profit
Segment Reporting Information
Equipment rentals gross profit	$ 979	777	$ 2,307	1,987
General rentals
Segment Reporting Information
Number of geographic regions entity operates in (locations) | region	11		11
Revenues	$ 1,894	1,679	$ 5,254	4,885
Depreciation and amortization expense	412	402	1,184	1,240
Capital expenditures			2,116	771
Assets	16,066		16,066		15,051
General rentals | Equipment rentals
Segment Reporting Information
Revenues	1,636	1,391	4,375	4,040
General rentals | Sales of rental equipment
Segment Reporting Information
Revenue from contract with customer	154	182	567	530
General rentals | Sales of new equipment
Segment Reporting Information
Revenue from contract with customer	31	47	111	145
General rentals | Contractor supplies sales
Segment Reporting Information
Revenue from contract with customer	19	17	53	48
General rentals | Service and other revenues
Segment Reporting Information
Revenue from contract with customer	54	42	148	122
General rentals | Equipment rentals gross profit
Segment Reporting Information
Equipment rentals gross profit	649	543	1,586	1,410
Specialty
Segment Reporting Information
Revenues	702	508	1,686	1,366
Depreciation and amortization expense	98	90	267	268
Capital expenditures			334	159
Assets	4,240		4,240		$ 2,817
Specialty | Equipment rentals
Segment Reporting Information
Revenues	641	470	1,520	1,246
Specialty | Sales of rental equipment
Segment Reporting Information
Revenue from contract with customer	29	17	77	53
Specialty | Sales of new equipment
Segment Reporting Information
Revenue from contract with customer	16	7	42	24
Specialty | Contractor supplies sales
Segment Reporting Information
Revenue from contract with customer	10	8	27	25
Specialty | Service and other revenues
Segment Reporting Information
Revenue from contract with customer	6	6	20	18
Specialty | Equipment rentals gross profit
Segment Reporting Information
Equipment rentals gross profit	$ 330	$ 234	$ 721	$ 577