Debt Instrument Denomination integral multiples.

No definition available.

Name:	gecc_DebtInstrumentDenominationIntegralMultiples
Namespace Prefix:	gecc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instrument, minimum denomination.

+ References

No definition available.

+ Details

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Namespace Prefix:	gecc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility covenant net asset percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	gecc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility covenant net assets.

+ References

No definition available.

+ Details

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Namespace Prefix:	gecc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
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

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+ 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

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+ Details

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

- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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+ Details

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

- Definition

Date the credit facility terminates, in YYYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-Publisher FASB
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+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) of the credit facility.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
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+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Indebtedness divided by net capital.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=gecc_SixPointSevenFivePercentNotesDueTwoThousandTwentyFiveMember
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Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=gecc_CityNationalBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
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Debt - Additional Information (Details)			9 Months Ended
Debt - Additional Information (Details)	Sep. 07, 2023	May 05, 2021 USD ($)	Sep. 30, 2023 USD ($)	Aug. 16, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jul. 09, 2021 USD ($)	Jun. 23, 2021 USD ($)	Jul. 05, 2019 USD ($)	Jun. 18, 2019 USD ($)	Feb. 09, 2018 USD ($)	Jan. 19, 2018 USD ($)	Jan. 11, 2018 USD ($)
Debt Instrument [Line Items]
Revolving line of credit borrowings outstanding					$ 10,000,000
Asset coverage ratio			168.4
Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, minimum denomination			$ 25
Debt instrument denomination integral multiples			$ 25
GECCM Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount										$ 1,500,000	$ 1,898,000	$ 43,000,000
Debt instrument, interest rate												6.75%
Maturity date			Jan. 31, 2025
GECCN Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount								$ 2,500,000	$ 42,500,000
Debt instrument, interest rate									6.50%
Percentage of principal amount redeemed	100.00%
GECCO Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount						$ 7,500,000	$ 50,000,000
Debt instrument, interest rate							5.875%
Maturity date			Jun. 30, 2026
GECCZ Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount				$ 40,000,000
Debt instrument, interest rate				8.75%
Maturity date			Sep. 30, 2028
Senior Secured Revolving Line of Credit \| Maximum
Debt Instrument [Line Items]
Line of credit facility covenant net assets		$ 65,000,000
Senior Secured Revolving Line of Credit \| Minimum
Debt Instrument [Line Items]
Line of credit facility covenant net assets percentage		150.00%
Senior Secured Revolving Line of Credit \| City National Bank
Debt Instrument [Line Items]
Revolving line of credit maximum borrowing capacity		$ 25,000,000
Increase revolving credit facility in aggregate amount		$ 25,000,000
Revolving line of credit, maturity date		May 05, 2024
Revolving line of credit borrowings outstanding			$ 0
Senior Secured Revolving Line of Credit \| City National Bank \| Minimum
Debt Instrument [Line Items]
Line of credit facility covenant net assets percentage		300.00%
Senior Secured Revolving Line of Credit \| City National Bank \| SOFR
Debt Instrument [Line Items]
Line of credit interest rate		3.50%
Senior Secured Revolving Line of Credit \| City National Bank \| Base Rate
Debt Instrument [Line Items]
Line of credit interest rate		2.00%