Acquisitions (Pro Forma Information) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Aug. 31, 2021	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues		$ 2,776	$ 2,596	$ 2,287	$ 2,057	$ 2,279	$ 2,187	$ 1,939	$ 2,125	$ 9,716	$ 8,530	$ 9,351
Pro forma revenues										9,860	8,872
Income (loss) before provision (benefit) for income taxes										1,846	1,139	1,514
Pro forma pretax income										1,846	1,115
Gain (loss) on extinguishment of debt	$ (30)									(30)	(183)	(61)
Merger related costs										3	0	$ 1
Impact of fair value mark-ups/useful life changes on depreciation
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										(11)	(25)
Impact of the fair value mark-up of acquired fleet on cost of rental equipment sales
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										(6)	(14)
Intangible asset amortization
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										(5)	(21)
Goodwill Impairment
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										0	14
Interest expense
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										(6)	(19)
Elimination of historic interest
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										23	24
Elimination of merger related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										12	0
Elimination of changes in the valuation of bifurcated derivatives in convertible notes
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										(16)	8
United Rentals and General Finance Corporation
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Income (loss) before provision (benefit) for income taxes										1,855	1,148
Gain (loss) on extinguishment of debt										(12)
General Finance Corporation
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues										144	342
Income (loss) before provision (benefit) for income taxes										9	$ 9
Merger related costs										$ 9