For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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Amount of expense related to write-down of receivables to the amount expected to be collected. Includes, but is not limited to, accounts receivable and notes receivable.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Revenue Recognition (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue	$ 56	$ 46
Contract with customer, liability, revenue recognized	0
Provision for doubtful accounts	$ 45	$ 40	$ 24
Customer concentration risk \| Revenues \| Largest customer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	1.00%	1.00%	1.00%
Customer concentration risk \| Accounts receivable
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	1.00%	1.00%
Owned Equipment Rentals \| Product concentration risk \| Revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	74.00%
Topic 840 \| Product concentration risk \| Total equipment rentals
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	79.00%
Topic 840 \| Owned Equipment Rentals \| Product concentration risk \| Total equipment rentals
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	86.00%
General rentals \| Product concentration risk \| Revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	81.00%
UNITED STATES \| Geographic Concentration Risk \| Revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Concentration risk, percentage (less than 1% of total revenues)	92.00%
Calculated under Revenue Guidance in Effect before Topic 606 \| Transferred at point in time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 0