XML 119 R98.htm IDEA: XBRL DOCUMENT
v3.21.2

Income Taxes - Additional information (Detail) - USD ($) | 12 Months Ended
--- | ---
Aug. 31, 2021 | Aug. 31, 2020 | Aug. 31, 2019 | Aug. 31, 2018 | Aug. 31, 2017
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Income tax and earnings from unconsolidated affiliates,Domestic u.s. operations | $ 30,700,000 | $ 71,200,000 | $ 75,000,000.0 |  |
Income tax and earnings from unconsolidated affiliates,Foreign operations | $ 22,100,000 | $ 53,600,000 | $ 78,200,000 |  |
Statutory federal corporate tax rate | 21.00% | 21.00% | 21.00% | 25.70% | 35.00%
Federal income tax expense (benefit), CARES Act | $ 36,600,000 |  |  |  |
Deferred tax assets, valuation allowance | 10,356,000 | $ 9,195,000 |  |  |
Net increase (decrease) in the valuation allowance | 1,100,000 |  |  |  |
Unrecognized tax benefits, excluding interest | 1,600,000 | 5,500,000 |  |  |
Accrued interest related to uncertain tax provisions | 400,000 | 1,100,000 |  |  |
Increase (reduction) in interest expense relating to reserves for uncertain tax provisions | (600,000) | $ 400,000 |  |  |
Accrued penalties related to uncertain tax reserves | 0 |  |  |  |
State |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Operating loss carryforwards | $ 68,200,000 |  |  |  |
Operating loss carryforwards expiration year | 2026 |  |  |  |
Credit carryforwards | $ 1,200,000 |  |  |  |
Credit carryforwards expiration year | 2022 |  |  |  |
Foreign |  |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |  |
Operating loss carryforwards | $ 34,500,000 |  |  |  |
Operating loss carryforwards expiration year | 2022 |  |  |  |
Operating loss carryforwards that do not expire | $ 26,000,000.0 |  |  |  |

X
- Definition Federal income tax expense (benefit), CARES Act. + References No definition available. + Details
Name: | gbx_FederalIncomeTaxExpenseBenefitCARESAct
Namespace Prefix: | gbx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Operating loss carryforwards expiration year. + References No definition available. + Details
Name: | gbx_OperatingLossCarryforwardsExpirationYear
Namespace Prefix: | gbx_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Operating loss carryforwards, not subject to expiration. + References No definition available. + Details
Name: | gbx_OperatingLossCarryforwardsNotSubjectToExpiration
Namespace Prefix: | gbx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Tax Credit Carryforward, Expiration Year + References No definition available. + Details
Name: | gbx_TaxCreditCarryforwardExpirationYear
Namespace Prefix: | gbx_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Unrecognized tax benefits, excluding interest accrued. + References No definition available. + Details
Name: | gbx_UnrecognizedTaxBenefitsExcludingInterestAccrued
Namespace Prefix: | gbx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.4) -URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)(2)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32687-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)(1)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.3) -URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)(1)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.3) -URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32559-109319 + Details
Name: | us-gaap_OperatingLossCarryforwards
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_OperatingLossCarryforwardsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32559-109319 + Details
Name: | us-gaap_TaxCreditCarryforwardAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319 + Details
Name: | us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of interest expense accrued for an underpayment of income taxes. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319 + Details
Name: | us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of interest expense for an underpayment of income taxes. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319 + Details
Name: | us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) in valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 + Details
Name: | us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=gbx_StateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=gbx_ForeignMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |