Acquisitions (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Asset acquisition, consideration transferred	$ 23	$ 28
Franchise Rights
Business Acquisition [Line Items]
Finite-lived intangible assets acquired	$ 28	$ 28
Acquired finite-lived intangible assets, weighted average useful life	1 year	2 years
Fleet
Business Acquisition [Line Items]
Property acquired	$ 22	$ 22

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
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-URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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- Definition

Amount of consideration transferred in asset acquisition. Includes, but is not limited to, cash, liability incurred by acquirer, and equity interest issued by acquirer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 30
-Paragraph 2
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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- Definition

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.

+ References

No definition available.

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- Definition

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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-Section 50
-Paragraph 1
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- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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