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Prospect Capital InterNotes® - Schedule Issued Notes (Details) - Prospect Capital InterNotes® - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023
Debt Instrument [Line Items]
Principal Amount	$ 151,592	$ 156,840	$ 17,867
Unsecured Debt
Debt Instrument [Line Items]
Principal Amount	$ 151,592	$ 156,840
Weighted Average Interest Rate	7.15%	7.14%
Unsecured Debt \| Minimum
Debt Instrument [Line Items]
Interest Rate Range	6.50%	5.75%
Unsecured Debt \| Maximum
Debt Instrument [Line Items]
Interest Rate Range	8.00%	8.00%
Unsecured Debt \| July 15, 2027 – July 15, 2028
Debt Instrument [Line Items]
Tenor at Origination (in years)	3 years
Principal Amount	$ 60,429
Weighted Average Interest Rate	6.96%
Unsecured Debt \| July 15, 2027 – July 15, 2028 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range	6.50%
Unsecured Debt \| July 15, 2027 – July 15, 2028 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range	7.50%
Unsecured Debt \| July 15, 2029 – July 15, 2030
Debt Instrument [Line Items]
Tenor at Origination (in years)	5 years
Principal Amount	$ 48,993
Weighted Average Interest Rate	7.18%
Unsecured Debt \| July 15, 2029 – July 15, 2030 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range	6.75%
Unsecured Debt \| July 15, 2029 – July 15, 2030 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range	7.75%
Unsecured Debt \| May 15, 2032 – July 15, 2032
Debt Instrument [Line Items]
Tenor at Origination (in years)	7 years
Principal Amount	$ 718
Weighted Average Interest Rate	8.00%
Unsecured Debt \| May 15, 2032 – July 15, 2032 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range	8.00%
Unsecured Debt \| May 15, 2032 – July 15, 2032 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range	8.00%
Unsecured Debt \| July 15, 2034 – December 15, 2034
Debt Instrument [Line Items]
Tenor at Origination (in years)	10 years
Principal Amount	$ 41,452
Weighted Average Interest Rate	7.39%
Unsecured Debt \| July 15, 2034 – December 15, 2034 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range	7.00%
Unsecured Debt \| July 15, 2034 – December 15, 2034 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range	7.75%
Unsecured Debt \| July 15, 2026 – June 15, 2027
Debt Instrument [Line Items]
Tenor at Origination (in years)		3 years
Principal Amount		$ 54,209
Weighted Average Interest Rate		6.72%
Unsecured Debt \| July 15, 2026 – June 15, 2027 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		5.75%
Unsecured Debt \| July 15, 2026 – June 15, 2027 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		7.25%
Unsecured Debt \| November 15, 2028 – June 15, 2029
Debt Instrument [Line Items]
Tenor at Origination (in years)		5 years
Principal Amount		$ 47,685
Weighted Average Interest Rate		7.20%
Unsecured Debt \| November 15, 2028 – June 15, 2029 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		6.75%
Unsecured Debt \| November 15, 2028 – June 15, 2029 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		7.75%
Unsecured Debt \| July 15, 2029 – November 15, 2029
Debt Instrument [Line Items]
Tenor at Origination (in years)		6 years
Principal Amount		$ 899
Weighted Average Interest Rate		6.02%
Unsecured Debt \| July 15, 2029 – November 15, 2029 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		6.00%
Unsecured Debt \| July 15, 2029 – November 15, 2029 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		6.25%
Unsecured Debt \| November 15, 2030 – December 15, 2030
Debt Instrument [Line Items]
Tenor at Origination (in years)		7 years
Principal Amount		$ 6,467
Weighted Average Interest Rate		7.87%
Unsecured Debt \| November 15, 2030 – December 15, 2030 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		7.50%
Unsecured Debt \| November 15, 2030 – December 15, 2030 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		8.00%
Unsecured Debt \| July 15, 2033 – June 15, 2034
Debt Instrument [Line Items]
Tenor at Origination (in years)		10 years
Principal Amount		$ 45,674
Weighted Average Interest Rate		7.54%
Unsecured Debt \| July 15, 2033 – June 15, 2034 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		6.25%
Unsecured Debt \| July 15, 2033 – June 15, 2034 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		8.00%
Unsecured Debt \| July 15, 2043 – November 15, 2043
Debt Instrument [Line Items]
Tenor at Origination (in years)		20 years
Principal Amount		$ 1,906
Weighted Average Interest Rate		6.58%
Unsecured Debt \| July 15, 2043 – November 15, 2043 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		6.50%
Unsecured Debt \| July 15, 2043 – November 15, 2043 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		7.50%