Consent fee paid to lienholder to support agreement.

No definition available.

Name:	gfn_ConsentFeePaidToLienholderToSupportAgreement
Namespace Prefix:	gfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt instrument fixed charge coverage ratio.

+ References

No definition available.

+ Details

Name:	gfn_DebtInstrumentFixedChargeCoverageRatio
Namespace Prefix:	gfn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Optional Redemption Price Percentage Of Principal Amount Redeemed

+ References

No definition available.

+ Details

Name:	gfn_DebtInstrumentOptionalRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix:	gfn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Weighted Average Interest Rate

+ References

No definition available.

+ Details

Name:	gfn_DebtInstrumentWeightedAverageInterestRate
Namespace Prefix:	gfn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Inter company dividends percentage on senior notes proceeds.

+ References

No definition available.

+ Details

Name:	gfn_InterCompanyDividendsPercentageOnSeniorNotesProceeds
Namespace Prefix:	gfn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Notes issued denominations.

+ References

No definition available.

+ Details

Name:	gfn_NotesIssuedDenominations
Namespace Prefix:	gfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Notes Issued Denominations And Multiples Of Denominations

+ References

No definition available.

+ Details

Name:	gfn_NotesIssuedDenominationsAndMultiplesOfDenominations
Namespace Prefix:	gfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Notes issued denominations and multiples of denominations per share.

+ References

No definition available.

+ Details

Name:	gfn_NotesIssuedDenominationsAndMultiplesOfDenominationsPerShare
Namespace Prefix:	gfn_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of holders concluded consent solicitation.

+ References

No definition available.

+ Details

Name:	gfn_PercentageOfHoldersConcludedConsentSolicitation
Namespace Prefix:	gfn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Underwriting Discount

+ References

No definition available.

+ Details

Name:	gfn_UnderwritingDiscount
Namespace Prefix:	gfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: 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(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ 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:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of long-term debt classified as other.

+ References

Reference 1: 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 2: 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))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: 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

+ Details

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

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=gfn_PacVanAndLoneStarLeasingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gfn_EquipmentFinancingAndOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=gfn_SecondSupplementalIndentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=gfn_RedemptionOnOrAfterJulyThirtyFirstTwoThousandAndSeventeenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_StatementGeographicalAxis=srt_AsiaPacificMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=srt_NorthAmericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Senior and Other Debt - Senior Notes and Other Debt - Additional Information (Details)			3 Months Ended	12 Months Ended
	Oct. 31, 2018 USD ($) $ / shares	Apr. 24, 2017 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 18, 2014 USD ($)
Pac Van and Lone Star Leasing
Senior and Other Debt
Intercompany dividends percentage on senior notes gross proceeds		80.00%
Equipment Financing and Other
Senior and Other Debt
Other debt			$ 9,608,000
Senior Notes 8.125%
Senior and Other Debt
Fixed charge coverage ratio			2.0
Senior Notes 8.125% \| Second Supplemental Indenture
Senior and Other Debt
Notes issued denominations and multiples of denominations	$ 25
Debt instrument, aggregate original issue discount		$ 10,780
Percentage of Shareholders concluded a consent solicitation	63.30%
Consent fee paid	$ 195,820
Notes issued denominations and multiples of denominations, per share \| $ / shares	$ 0.10
Senior Notes 8.125% \| On or after July 31, 2017
Senior and Other Debt
Senior notes redemption percentage on principal amount			100.00%
Senior Notes 8.125% \| Unsecured senior notes
Senior and Other Debt
Aggregate principal amount of notes issued		5,390,000	$ 77,390,000		$ 72,000,000
Notes issued denominations and multiples of denominations					$ 25
Notes issued denominations		24.95
Aggregate principal amount of senior notes issued, net of unamortized debt issuance costs			76,908,000	$ 76,763,000
Unamortized debt issuance costs			$ 482,000	$ 627,000
Proceeds from issuance of unsecured senior notes net off underwriting discounts and offering costs		5,190,947
Underwriting discount		188,273
Interest rate of senior notes					8.125%
Other \| Asia-Pacific
Senior and Other Debt
Weighted-average interest rate			7.20%	7.90%
Other \| North America
Senior and Other Debt
Weighted-average interest rate			4.60%	6.10%
Wells Fargo Credit Facility
Senior and Other Debt
Repayment of indebtedness		$ 4,303,376