Debt instrument, maturity year.

No definition available.

Name:	gbx_DebtInstrumentMaturityYear
Namespace Prefix:	gbx_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instruments additional interest rate per annum.

+ References

No definition available.

+ Details

Name:	gbx_DebtInstrumentsAdditionalInterestRatePerAnnum
Namespace Prefix:	gbx_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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-Publisher FASB
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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
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+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_CreditFacilityAxis=gbx_GBXLeasingWarehouseFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=gbx_GbxlISeries20221ClassASecuredRailcarEquipmentNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=gbx_GbxlISeries20221ClassBSecuredRailcarEquipmentNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Asset Backed Securities - Additional Information (Detail) - USD ($) $ in Millions	Feb. 09, 2022	Aug. 31, 2022	Aug. 31, 2021
Debt Instrument [Line Items]
Debt issuance costs, net		$ 8.7	$ 8.6
GBX Leasing
Debt Instrument [Line Items]
Debt, Principal amount	$ 323.3	$ 323.3
Debt issuance costs, net	$ 5.0
Debt instrument, maturity year	2052
Debt instruments additional interest rate per annum	4.00%
GBX Leasing \| GBXL I Series 2022-1 Class A Secured Railcar Equipment Notes
Debt Instrument [Line Items]
Debt, Principal amount	$ 302.6
Debt instrument, interest rate	2.87%
Debt instrument, maturity date	Feb. 20, 2052
GBX Leasing \| GBXL I Series 2022-1 Class B Secured Railcar Equipment Notes
Debt Instrument [Line Items]
Debt, Principal amount	$ 20.7
Debt instrument, interest rate	3.45%
Debt instrument, maturity date	Feb. 20, 2052