Revenue Recognition - Additional information (Detail) $ in Millions	3 Months Ended	6 Months Ended
Feb. 29, 2020 USD ($)	Feb. 29, 2020 USD ($)
Revenue From Contract With Customers [Line Items]
Revenue recognized from contract with customers liability	$ 3.8	$ 24.5
Railcar sales
Revenue From Contract With Customers [Line Items]
Expected revenue recognized in the reminder of fiscal year	900.0	900.0
Services
Revenue From Contract With Customers [Line Items]
Expected revenue recognized in the reminder of fiscal year	$ 140.1	$ 140.1
Expected performance percentage	51.00%	51.00%

Revenue From Contract With Customers [Line Items]

No definition available.

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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 http://asc.fasb.org/extlink&oid=118956577&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 http://asc.fasb.org/extlink&oid=118956577&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 http://asc.fasb.org/extlink&oid=118956577&loc=SL49130556-203045

+ Details

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- Details

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- Details

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