Related Party Transactions - Additional Information (Detail) - Axis LLC - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Related Party Transaction [Line Items]
Percentage of ownership in entity	41.90%		41.90%
Railcar Components
Related Party Transaction [Line Items]
Purchases of goods from related party	$ 3.3	$ 2.2	$ 6.1	$ 6.0

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant