Schedule of Concentration Risk of Total Fleet Lease Rental Income (Detail) - Total Fleet Lease Rental Income - Customer Concentration Risk	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Customer A
Capital Leased Assets [Line Items]
Percentage of lease rental income	21.00%	17.80%	14.80%
Customer B
Capital Leased Assets [Line Items]
Percentage of lease rental income	12.20%	13.10%	13.50%
Customer C
Capital Leased Assets [Line Items]
Percentage of lease rental income	12.10%	9.70%	8.70%

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
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