XML 110 R93.htm IDEA: XBRL DOCUMENT v3.25.3

Earnings Per Share - Reconciliation of Shares Used in Computation of Basic and Diluted Earnings Per Common Share (Parenthetical) (Detail)	Aug. 31, 2025	Aug. 31, 2024	Feb. 01, 2024	Aug. 31, 2023
2.875% Convertible senior notes, due 2024
Earnings Per Share Disclosure [Line Items]
Debt instrument, interest rate	2.875%	2.875%	2.875%	2.875%
2.875% Convertible senior notes, due 2028
Earnings Per Share Disclosure [Line Items]
Debt instrument, interest rate	2.875%	2.875%		2.875%

X

- Definition

Earnings Per Share Disclosure [Line Items]

+ References

No definition available.

+ Details

Name:	gbx_EarningsPerShareDisclosureLineItems
Namespace Prefix:	gbx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(a)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

+ Details

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

X

- Details

Name:	us-gaap_DebtInstrumentAxis=gbx_TwoPointEightSevenFiveConvertibleSeniorNotesDue2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=gbx_TwoPointEightSevenFiveConvertibleSeniorNotesDue2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: