Revenue Recognition (Revenue summarized by type and applicable accounting standard) (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
Disaggregation of Revenue [Line Items]
Re-rent revenue									$ 157
Revenues	$ 2,456	$ 2,488	$ 2,290	$ 2,117	$ 2,306	$ 2,116	$ 1,891	$ 1,734	9,351	$ 8,047	$ 6,641
Owned equipment rentals
Disaggregation of Revenue [Line Items]
Owned equipment rentals									6,777
Owned equipment rentals										5,946	4,928
Re-rent revenue
Disaggregation of Revenue [Line Items]
Re-rent revenue									155
Re-rent revenue										138	106
Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									564	477	389
Other									468	379	292
Revenues									1,032	856	681
Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									7,964	6,940	5,715
Revenues									7,964	6,940	5,715
Sales of rental equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									831	664	550
Sales of new equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									268	208	178
Contractor supplies sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									104	91	80
Service and other revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									184	144	118
Topic 842
Disaggregation of Revenue [Line Items]
Revenues									7,288
Topic 842 | Owned equipment rentals
Disaggregation of Revenue [Line Items]
Owned equipment rentals									6,777
Topic 842 | Re-rent revenue
Disaggregation of Revenue [Line Items]
Re-rent revenue									155
Topic 842 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									0
Other									356
Revenues									356
Topic 842 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues									7,288
Topic 606
Disaggregation of Revenue [Line Items]
Revenues									2,063	1,676
Topic 606 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									564	477
Other									112	92
Revenues									676	569
Topic 606 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues									676	569
Topic 606 | Sales of rental equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									831	664
Topic 606 | Sales of new equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									268	208
Topic 606 | Contractor supplies sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									104	91
Topic 606 | Service and other revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax									$ 184	144
Topic 840
Disaggregation of Revenue [Line Items]
Revenues										6,371	5,262
Topic 840 | Owned equipment rentals
Disaggregation of Revenue [Line Items]
Owned equipment rentals										5,946	4,928
Topic 840 | Re-rent revenue
Disaggregation of Revenue [Line Items]
Re-rent revenue										138	106
Topic 840 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax										0	0
Other										287	228
Revenues										287	228
Topic 840 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues										$ 6,371	5,262
Topic 605
Disaggregation of Revenue [Line Items]
Revenues											1,379
Topic 605 | Ancillary and Other Rental Revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax											389
Other											64
Revenues											453
Topic 605 | Total equipment rentals
Disaggregation of Revenue [Line Items]
Revenues											453
Topic 605 | Sales of rental equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax											550
Topic 605 | Sales of new equipment
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax											178
Topic 605 | Contractor supplies sales
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax											80
Topic 605 | Service and other revenues
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax											$ 118