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Revenue Recognition (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
Revenue Recognition (Narrative) (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Contract with customer, liability	$ 57,000,000		$ 57,000,000		$ 55,000,000
Accounts receivable, net	1,324,000,000		1,324,000,000		1,530,000,000
Allowance for doubtful accounts	114,000,000		114,000,000		$ 103,000,000
Bad debt expense	2,000,000		8,000,000
Contract with customer, asset	0		0
Revenue recognized	0	$ 0	0	$ 0
Contract with customer, performance obligation satisfied in previous period	$ 0	$ 0	$ 0	$ 0
Accounts Receivable \| Customer concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk			1.00%		1.00%
Revenues \| Product concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk			78.00%
Revenues \| Largest customer \| Customer concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk			1.00%		1.00%	1.00%	1.00%
Owned equipment rentals \| Revenues \| Product concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk			72.00%
US \| Revenues \| Geographic Concentration Risk
Property, Plant and Equipment [Line Items]
Concentration risk			92.00%
General rentals \| Revenues \| Product concentration risk
Property, Plant and Equipment [Line Items]
Concentration risk			78.00%