XML 105 R84.htm IDEA: XBRL DOCUMENT
v3.21.2

Notes Payable, Net - Principal Payments on Notes Payable (Parenthetical) (Detail) $ in Millions | 12 Months Ended
--- | ---
Aug. 31, 2021 USD ($)
2024 Convertible Senior Notes |
Debt Instrument [Line Items] |
Debt instrument redemption description | The repayment of the $47.7 million of Convertible senior notes due February 2024 and the $373.8 million of Convertible senior notes due April 2028 is assumed to occur at the scheduled maturity instead of assuming an earlier conversion by the holders.
February 2024 Convertible Senior Notes |
Debt Instrument [Line Items] |
Convertible senior notes | $ 47.7
April 2028 Convertible Senior Notes |
Debt Instrument [Line Items] |
Convertible senior notes | $ 373.8

X
- Definition Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(13)) -URI http://asc.fasb.org/extlink&oid=120401414&loc=d3e603758-122996 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
Name: | us-gaap_ConvertibleNotesPayable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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

X
- Definition Description of debt redemption features under terms of the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph e -URI http://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentRedemptionDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gbx_TwoThousandTwentyFourConvertibleSeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gbx_ConvertibleSeniorNotesFebruary2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gbx_ConvertibleSeniorNotesApril2028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |