Debt - Additional Information (Details)						9 Months Ended
Debt - Additional Information (Details)	Aug. 29, 2025 USD ($)	Aug. 13, 2025 USD ($)	Oct. 12, 2024	Nov. 22, 2023	May 05, 2021 USD ($)	Sep. 30, 2025 USD ($)	Oct. 02, 2025 USD ($)	Sep. 11, 2025 USD ($)	Oct. 03, 2024 USD ($)	Sep. 19, 2024 USD ($)	Jul. 09, 2024 USD ($)	Apr. 25, 2024 USD ($)	Apr. 17, 2024 USD ($)	Aug. 16, 2023 USD ($)	Jul. 09, 2021 USD ($)	Jun. 23, 2021 USD ($)	Feb. 09, 2018 USD ($)	Jan. 19, 2018 USD ($)	Jan. 11, 2018 USD ($)
Debt Instrument [Line Items]
Asset coverage ratio						168.2
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	$ 1,900,000	$ 43,000,000
Debt instrument, interest rate																			6.75%
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 redemption price of principal amount redeemed	$ 40,000,000
Debt Instrument, aggregate principal amount														$ 40,000,000
Debt instrument, interest rate														8.75%
Percentage of principal amount redeemed	100.00%
GECCI Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount											$ 22,000,000	$ 4,500,000	$ 30,000,000
Debt instrument, interest rate													8.50%
Maturity date						Apr. 30, 2029
GECCH Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount									$ 5,400,000	$ 36,000,000
Debt instrument, interest rate										8.125%
Maturity date						Dec. 31, 2029
GECCG Notes
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount								$ 50,000,000
Debt instrument, interest rate								7.75%
Maturity date						Dec. 31, 2030
GECCG Notes \| Subsequent Events
Debt Instrument [Line Items]
Debt Instrument, aggregate principal amount							$ 7,500,000
Senior Secured Revolving Line of Credit
Debt Instrument [Line Items]
Revolving line of credit maximum borrowing capacity		$ 25,000,000
Commitment fee percentage for unused portion		0.50%
Commitment fee percentage decreases		0.375%
Senior Secured Revolving Line of Credit \| Maximum
Debt Instrument [Line Items]
Line of credit facility covenant net assets		$ 80,000,000			$ 80,000,000
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 commitment maximum borrowing capacity		50,000,000
Revolving line of credit maximum borrowing capacity		90,000,000			$ 25,000,000
Increase revolving credit facility in aggregate amount		$ 40,000,000			$ 25,000,000
Revolving line of credit, maturity date				May 05, 2027	May 05, 2024
Debt instrument, interest rate		5.875%
Senior Secured Revolving Line of Credit \| City National Bank \| Minimum Deposit Test Met \| Share-Based Payment Arrangement, Tranche One [Member]
Debt Instrument [Line Items]
Line of credit interest rate		2.50%
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 \| Base Rate \| Minimum Deposit Test Met
Debt Instrument [Line Items]
Line of credit interest rate					1.50%

Great Elm Capital Corp. 10-Q