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Revenue Recognition - Additional information (Detail) - USD ($) $ in Millions | 12 Months Ended
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Aug. 31, 2022 | Aug. 31, 2021
Revenue From Contract With Customers [Line Items] |  |
Revenue recognized from contract with customers liability | $ 16.4 | $ 7.4
Railcar sales |  |
Revenue From Contract With Customers [Line Items] |  |
Expected revenue recognized in the reminder of fiscal year | 2,100.0 |
Services |  |
Revenue From Contract With Customers [Line Items] |  |
Expected revenue recognized in the reminder of fiscal year | $ 123.8 |
Expected performance percentage | 54.00% |

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- Definition Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130549-203045 + Details
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- Definition Amount of transaction price allocated to performance obligation that has not been recognized as revenue. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130556-203045 + Details
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- Definition Percentage of remaining performance obligation to total remaining performance obligation not recognized as revenue. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (b)(1) -URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130556-203045 + Details
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