Related Party Transactions - Additional Information (Detail) - Axis LLC - USD ($) $ in Millions	3 Months Ended
	Nov. 30, 2025	Nov. 30, 2024
Related Party Transaction [Line Items]
Percentage of ownership in entity	41.90%
Railcar Components
Related Party Transaction [Line Items]
Purchases of goods from related party	$ 1.7	$ 3.1

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.

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+ Details

GREENBRIER COMPANIES INC 10-Q