Cover - shares	3 Months Ended
	Sep. 30, 2022	Nov. 08, 2022
Document Information [Line Items]
Document Type	10-Q
Document Annual Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	814-00659
Entity Registrant Name	PROSPECT CAPITAL CORP
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	43-2048643
Entity Address, Address Line One	10 East 40th Street
Entity Address, Address Line Two	42nd Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10016
City Area Code	212
Local Phone Number	448-0702
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		397,622,474
Entity Central Index Key	0001287032
Current Fiscal Year End Date	--06-30
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Stock, par value $0.001 per share
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	PSEC
Security Exchange Name	NASDAQ
5.35% Series A Fixed Rate Cumulative Perpetual Preferred Stock, par value $0.001
Document Information [Line Items]
Title of 12(b) Security	5.35% Series A Fixed Rate Cumulative Perpetual Preferred Stock, par value $0.001
Trading Symbol	PSEC PRA
Security Exchange Name	NYSE