Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	Apr. 25, 2024
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Registrant Name	Great Elm Capital Corp.
Entity Central Index Key	0001675033
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity File Number	814-01211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	81-2621577
Entity Address, Address Line One	3801 PGA Boulevard
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
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		9,452,382
Common Stock
Document Information [Line Items]
Trading Symbol	GECC
Title of 12(b) Security	Common stock, par value $0.01 per share
Security Exchange Name	NASDAQ
6.75% Notes due 2025
Document Information [Line Items]
Trading Symbol	GECCM
Title of 12(b) Security	6.75% Notes due 2025
Security Exchange Name	NASDAQ
5.875% Notes due 2026
Document Information [Line Items]
Trading Symbol	GECCO
Title of 12(b) Security	5.875% Notes due 2026
Security Exchange Name	NASDAQ
8.75% Notes due 2028
Document Information [Line Items]
Trading Symbol	GECCZ
Title of 12(b) Security	8.75% Notes due 2028
Security Exchange Name	NASDAQ
8.50% Notes due 2029
Document Information [Line Items]
Trading Symbol	GECCI
Title of 12(b) Security	8.50% Notes due 2029
Security Exchange Name	NASDAQ