Nature of Operations - Additional Information (Detail)	12 Months Ended
Aug. 31, 2022 Vehicle Segment
Segment Reporting Information [Line Items]
Number of reportable segments \| Segment	3
Leasing & Management Services
Segment Reporting Information [Line Items]
Number of railcars owned	12,200
Number of railcars that get services	408,000

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8672-108599

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration