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Revenue Recognition (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Contract with customer, liability	$ 88		$ 83
Accounts receivable, net	1,607		1,677
Allowance for doubtful accounts	116		$ 112
Contract with customer, asset	0
Revenue recognized	0	$ 0
Contract with customer, performance obligation satisfied in previous period	$ 0	$ 0
Revenues \| Largest customer \| Customer concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk	1.00%
Accounts Receivable \| Largest customer \| Customer concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk	1.00%		1.00%
Owned equipment rentals \| Revenues \| Product concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk	71.00%
Equipment Rental \| Revenues \| Product concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk	78.00%
US \| Revenues \| Geographic Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk	90.00%
General rentals \| Revenues \| Product concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk	75.00%