| Document and Entity Information | Sep. 12, 2024 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001675033 |
| Document Type | 8-K |
| Document Period End Date | Sep. 12, 2024 |
| Entity Registrant Name | Great Elm Capital Corp. |
| Entity Incorporation State Country Code | MD |
| Entity File Number | 814-01211 |
| Entity Tax Identification Number | 81-2621577 |
| Entity Address, Address Line One | 3801 PGA Blvd. |
| Entity Address, Address Line Two | Suite 603 |
| Entity Address, City or Town | Palm Beach Gardens |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33410 |
| City Area Code | (617) |
| Local Phone Number | 375-3006 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common stock, $0.01 par value |
| Trading Symbol | GECC |
| Security Exchange Name | NASDAQ |
| M 6.75 Notes Due 2025 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 6.75% Notes due 2025 |
| Trading Symbol | GECCM |
| Security Exchange Name | NASDAQ |
| M 5.875 Notes Due 2026 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 5.875% Notes due 2026 |
| Trading Symbol | GECCO |
| Security Exchange Name | NASDAQ |
| M 8.75 Notes Due 2028 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 8.75% Notes due 2028 |
| Trading Symbol | GECCZ |
| Security Exchange Name | NASDAQ |
| M 8.50 Notes Due 2029 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 8.50% Notes due 2029 |
| Trading Symbol | GECCI |
| Security Exchange Name | NASDAQ |
