Schedule of Concentration Risk of Total Fleet Gross Accounts Receivable (Detail) - Gross Accounts Receivable - Customer Concentration Risk	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Customer A
Concentration Risk [Line Items]
Percentage of lease rental income	45.90%	37.70%
Customer B
Concentration Risk [Line Items]
Percentage of lease rental income	6.30%	16.70%
Customer C
Concentration Risk [Line Items]
Percentage of lease rental income	17.50%	11.60%

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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