Revenue Recognition (Revenue summarized by type and applicable accounting standard) (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
Disaggregation of Revenue [Line Items]
Re-rent revenue									$ 142	$ 157
Revenues	$ 2,279	$ 2,187	$ 1,939	$ 2,125	$ 2,456	$ 2,488	$ 2,290	$ 2,117	8,530	9,351	$ 8,047
Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues									7,140	7,964	6,940
Owned equipment rentals
Disaggregation of Revenue [Line Items]
Owned equipment rentals									6,056	6,777
Owned equipment rentals											5,946
Re-rent revenue
Disaggregation of Revenue [Line Items]
Re-rent revenue									142	155
Re-rent revenue											138
Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									506	564	477
Other									436	468	379
Revenues									942	1,032	856
Sales of rental equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									858	831	664
Sales of new equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									247	268	208
Contractor supplies sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									98	104	91
Service and other revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									187	184	144
Topic 842
Disaggregation of Revenue [Line Items]
Revenues									6,536	7,288
Topic 842 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues									6,536	7,288
Topic 842 | Owned equipment rentals
Disaggregation of Revenue [Line Items]
Owned equipment rentals									6,056	6,777
Topic 842 | Re-rent revenue
Disaggregation of Revenue [Line Items]
Re-rent revenue									142	155
Topic 842 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Other									338	356
Revenues									338	356
Topic 606
Disaggregation of Revenue [Line Items]
Revenues									1,994	2,063	1,676
Topic 606 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues									604	676	569
Topic 606 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									506	564	477
Other									98	112	92
Revenues									604	676	569
Topic 606 | Sales of rental equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									858	831	664
Topic 606 | Sales of new equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									247	268	208
Topic 606 | Contractor supplies sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									98	104	91
Topic 606 | Service and other revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									$ 187	$ 184	144
Topic 840
Disaggregation of Revenue [Line Items]
Revenues											6,371
Topic 840 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues											6,371
Topic 840 | Owned equipment rentals
Disaggregation of Revenue [Line Items]
Owned equipment rentals											5,946
Topic 840 | Re-rent revenue
Disaggregation of Revenue [Line Items]
Re-rent revenue											138
Topic 840 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Other											287
Revenues											$ 287