Prospect Capital InterNotes® - Schedule Issued Notes (Details) - Prospect Capital InterNotes - USD ($) $ in Thousands	3 Months Ended
Sep. 30, 2022	Sep. 30, 2021
Debt Instrument [Line Items]
Principal Amount	$ 2,624	$ 87,657
Unsecured Debt
Debt Instrument [Line Items]
Principal Amount	$ 2,624	$ 87,657
Weighted Average Interest Rate	4.50%	3.35%
Unsecured Debt \| Minimum
Debt Instrument [Line Items]
Interest Rate Range	4.50%	2.25%
Unsecured Debt \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		4.00%
Unsecured Debt \| July 15, 2027 – September 15, 2027
Debt Instrument [Line Items]
Tenor at Origination (in years)	5 years
Principal Amount	$ 2,624
Interest Rate Range	4.50%
Weighted Average Interest Rate	4.50%
Unsecured Debt \| July 15, 2026 – September 15, 2026
Debt Instrument [Line Items]
Tenor at Origination (in years)		5 years
Principal Amount		$ 15,681
Weighted Average Interest Rate		2.42%
Unsecured Debt \| July 15, 2026 – September 15, 2026 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		2.25%
Unsecured Debt \| July 15, 2026 – September 15, 2026 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		2.50%
Unsecured Debt \| July 15, 2028 – September 15, 2028
Debt Instrument [Line Items]
Tenor at Origination (in years)		7 years
Principal Amount		$ 17,016
Weighted Average Interest Rate		2.96%
Unsecured Debt \| July 15, 2028 – September 15, 2028 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		2.75%
Unsecured Debt \| July 15, 2028 – September 15, 2028 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		3.00%
Unsecured Debt \| July 15, 2031 – September 15, 2031
Debt Instrument [Line Items]
Tenor at Origination (in years)		10 years
Principal Amount		$ 17,027
Weighted Average Interest Rate		3.29%
Unsecured Debt \| July 15, 2031 – September 15, 2031 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		3.15%
Unsecured Debt \| July 15, 2031 – September 15, 2031 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		3.40%
Unsecured Debt \| July 15, 2033
Debt Instrument [Line Items]
Tenor at Origination (in years)		12 years
Principal Amount		$ 2,422
Interest Rate Range		3.70%
Weighted Average Interest Rate		3.70%
Unsecured Debt \| July 15, 2036 – September 15, 2036
Debt Instrument [Line Items]
Tenor at Origination (in years)		15 years
Principal Amount		$ 12,317
Weighted Average Interest Rate		3.82%
Unsecured Debt \| July 15, 2036 – September 15, 2036 \| Minimum
Debt Instrument [Line Items]
Interest Rate Range		3.50%
Unsecured Debt \| July 15, 2036 – September 15, 2036 \| Maximum
Debt Instrument [Line Items]
Interest Rate Range		4.00%
Unsecured Debt \| July 15, 2051 – September 15, 2051
Debt Instrument [Line Items]
Tenor at Origination (in years)		30 years
Principal Amount		$ 23,194
Interest Rate Range		4.00%
Weighted Average Interest Rate		4.00%

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3255-108585

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