Portfolio Investments - Industries and Geographical Locations Comprising Greater than 10% of Portfolio Fair Value (Details) - USD ($) $ in Thousands		6 Months Ended		12 Months Ended
		Dec. 31, 2023		Jun. 30, 2023
Concentration Risk [Line Items]
Cost		$ 7,633,623	[1],[2]	$ 7,800,596
Fair Value	[3]	7,631,846	[1],[2]	7,724,931
California
Concentration Risk [Line Items]
Cost		970,206		933,559
Fair Value		$ 820,213		$ 791,860
Investments at Fair Value | Industry Concentration Risk
Concentration Risk [Line Items]
% of Portfolio		100.00%		100.00%
Investments at Fair Value | Geographic Concentration Risk | California
Concentration Risk [Line Items]
% of Portfolio		10.70%		10.30%
Equity Real Estate Investment Trusts (REITs)
Concentration Risk [Line Items]
Cost		$ 807,100		$ 741,133
Fair Value		$ 1,357,907		$ 1,437,796
Equity Real Estate Investment Trusts (REITs) | Investments at Fair Value | Industry Concentration Risk
Concentration Risk [Line Items]
% of Portfolio		17.80%		18.60%
Health Care Providers & Services
Concentration Risk [Line Items]
Cost		$ 670,173		$ 687,813
Fair Value		$ 772,888		$ 798,365
Health Care Providers & Services | Investments at Fair Value | Industry Concentration Risk
Concentration Risk [Line Items]
% of Portfolio		10.10%		10.30%
Consumer Finance
Concentration Risk [Line Items]
Cost		$ 647,029		$ 625,033
Fair Value		$ 742,471		$ 736,635
Consumer Finance | Investments at Fair Value | Industry Concentration Risk
Concentration Risk [Line Items]
% of Portfolio		9.70%		9.50%
All Other Industries
Concentration Risk [Line Items]
Cost		$ 5,509,321		$ 5,746,617
Fair Value		$ 4,758,580		$ 4,752,135
All Other Industries | Investments at Fair Value | Industry Concentration Risk
Concentration Risk [Line Items]
% of Portfolio		62.40%		61.60%

[1] The following shows the composition of our investment portfolio at cost by control designation, investment type and by industry as of December 31, 2023:

Industry1st Lien
Term Loan2nd Lien
Term LoanSubordinated Structured NotesUnsecured Debt Equity (B) Cost TotalControl InvestmentsAerospace & Defense$54,739 $— $— $— $55,581 $110,320 Commercial Services & Supplies129,917 — — 7,200 27,349 164,466 Construction & Engineering80,646 — — — 12,053 92,699 Consumer Finance517,163 — — — 82,844 600,007 Diversified Consumer Services— — — — 2,378 2,378 Energy Equipment & Services110,845 — — — 221,800 332,645 Equity Real Estate Investment Trusts (REITs)787,070 — — — 20,030 807,100 Health Care Providers & Services304,456 — — — 45,118 349,574 Machinery37,322 — — — 6,867 44,189 Media29,723 — — — — 29,723 Online Lending20,630 — — — — 20,630 Personal Products94,320 — — — 189,295 283,615 Trading Companies & Distributors35,163 — — — 32,500 67,663 Structured Finance210,000 — — — — 210,000 Total Control Investments$2,411,994 $— $— $7,200 $695,815 $3,115,009 Affiliate InvestmentsCommercial Services & Supplies$— $— $— $— $10,162 $10,162  Total Affiliate Investments $— $— $— $— $10,162 $10,162 Non-Control/Non-Affiliate InvestmentsAir Freight & Logistics$93,113 $95,000 $— $— $— $188,113 Automobile Components22,162 86,693 — — 25,697 134,552 Building Products— 35,000 — — — 35,000 Capital Markets— 42,500 — — — 42,500 Commercial Services & Supplies220,282 153,306 — — 2,750 376,338 Communications Equipment9,366 51,595 — — — 60,961 Consumer Finance47,022 — — — — 47,022 Distributors210,673 89,178 — — — 299,851 Diversified Consumer Services87,720 — — — 23,898 111,618 Diversified Financial Services36,348 — — — — 36,348 Diversified Telecommunication Services38,317 122,061 — — — 160,378 Electrical Equipment62,460 — — — — 62,460 Food & Staples Retailing26,941 — — — — 26,941 Food Products— 134,971 — — — 134,971 Health Care Providers & Services186,643 132,410 — — 1,546 320,599 Health Care Technology133,289 — — — — 133,289 Hotels, Restaurants & Leisure22,845 — — — — 22,845 Household Durables123,937 29,820 — — 3,501 157,258 Interactive Media & Services145,981 — — — — 145,981 Internet & Direct Marketing Retail2,416 18,311 — — — 20,727 IT Services197,456 148,300 — — — 345,756 Leisure Products88,662 — — — 1 88,663 Machinery51,504 9,991 — — — 61,495 Media42,858 — — — 26,991 69,849 Pharmaceuticals98,228 — — — — 98,228 Professional Services87,162 124,156 — — — 211,318 Software— 52,377 — — — 52,377 Textiles, Apparel & Luxury Goods176,264 — — — — 176,264 Structured Finance (A)— — 886,750 — — 886,750  Total Non-Control/Non-Affiliate $2,211,649 $1,325,669 $886,750 $— $84,384 $4,508,452 Total Portfolio Investment Cost$4,623,643 $1,325,669 $886,750 $7,200 $790,361 $7,633,623  The following table shows the composition of our investment portfolio at fair value by control designation, investment type and by industry as of December 31, 2023: Industry1st Lien
Term Loan2nd Lien
Term LoanSubordinated Structured NotesUnsecured Debt Equity (B) Fair Value TotalFair Value % of Net Assets Applicable to Common StockControl Investments Aerospace & Defense $54,739 $— $— $— $9,903 $64,642 1.8 % Commercial Services & Supplies 71,443 — — 7,200 24,270 102,913 2.8 % Construction & Engineering 80,646 — — — 131,898 212,544 5.8 % Consumer Finance 514,070 — — — 210,346 724,416 19.7 % Diversified Consumer Services — — — — 3,242 3,242 0.1 % Energy Equipment & Services 95,244 — — — 12,485 107,729 2.9 %Equity Real Estate Investment Trusts (REITs)787,070 — — — 570,837 1,357,907 36.8 % Health Care Providers & Services 304,456 — — — 152,787 457,243 12.4 % Machinery 37,322 — — — 65,009 102,331 2.8 % Media 29,723 — — — 59,510 89,233 2.4 % Online Lending 20,630 — — — — 20,630 0.6 % Personal Products 68,108 — — — — 68,108 1.8 % Trading Companies & Distributors 35,163 — — — 24,874 60,037 1.6 %Structured Finance (A)210,000 — — — — 210,000 5.7 %Total Control Investments$2,308,614 $— $— $7,200 $1,265,161 $3,580,975 97.2 %Fair Value % of Net Assets62.7 %— %— %0.2 %34.3 %97.2 %Affiliate InvestmentsCommercial Services & Supplies$— $— $— $— $14,292 $14,292 0.4 %Total Affiliate Investments$— $— $— $— $14,292 $14,292 0.4 %Fair Value % of Net Assets— %— %— %— %0.4 %0.4 %Non-Control/Non-Affiliate InvestmentsAir Freight & Logistics$90,433 $93,761 $— $— $— $184,194 5.0 %Automobile Components22,198 86,852 — — 1,934 110,984 3.0 %Building Products— 33,870 — — — 33,870 0.9 %Capital Markets— 42,500 — — — 42,500 1.2 %Commercial Services & Supplies220,533 153,142 — — 17,671 391,346 10.6 %Communications Equipment8,058 35,970 — — — 44,028 1.2 %Consumer Finance18,055 — — — — 18,055 0.5 %Distributors210,325 7,408 — — 43,627 261,360 7.1 %Diversified Consumer Services87,889 — — — 18,400 106,289 2.9 %Diversified Financial Services36,348 — — — — 36,348 1.0 %Diversified Telecommunication Services38,409 121,933 — — — 160,342 4.4 %Electrical Equipment62,460 — — — — 62,460 1.7 %Food & Staples Retailing26,625 — — — — 26,625 0.7 %Food Products— 127,474 — — — 127,474 3.5 %Health Care Providers & Services185,266 128,096 — — 2,283 315,645 8.6 %Health Care Technology133,735 — — — — 133,735 3.6 %Hotels, Restaurants & Leisure16,981 — — — — 16,981 0.5 %Household Durables123,937 23,000 — — 1,411 148,348 4.0 %Interactive Media & Services145,981 — — — — 145,981 4.0 %Internet & Direct Marketing Retail2,406 14,338 — — — 16,744 0.5 %IT Services196,480 141,183 — — — 337,663 9.1 %Leisure Products88,489 — — — — 88,489 2.4 %Machinery51,834 10,000 — — — 61,834 1.7 %Media40,859 — — — — 40,859 1.1 %Pharmaceuticals98,751 — — — — 98,751 2.7 %Professional Services85,396 111,650 — — — 197,046 5.2 % Industry1st Lien
Term Loan2nd Lien
Term LoanSubordinated Structured NotesUnsecured Debt Equity (B) Fair Value TotalFair Value % of Net Assets Applicable to Common StockSoftware— 50,873 — — — 50,873 1.4 %Textiles, Apparel & Luxury Goods176,264 — — — — 176,264 4.8 %Structured Finance (A)— — 601,491 — — 601,491 16.3 %Total Non-Control/Non-Affiliate$2,167,712 $1,182,050 $601,491 $— $85,326 $4,036,579 109.6 %Fair Value % of Net Assets58.9 %32.1 %16.3 %— %2.3 %109.6 %Total Portfolio$4,476,326 $1,182,050 $601,491 $7,200 $1,364,779 $7,631,846 207.2 %Fair Value % of Net Assets121.6 %32.1 %16.3 %0.2 %37.0 %207.2 % (A) Our SSN investments do not have industry concentrations and as such have been separated in the tables above. (B) Equity, unless specifically stated otherwise, includes our investments in preferred stock, common stock, membership interests, net profits interests, net operating income interests, net revenue interests, overriding royalty interests, escrows receivable, and warrants.

[2] The terms “Prospect,” “the Company,” “we,” “us” and “our” mean Prospect Capital Corporation and its subsidiaries unless the context specifically requires otherwise. The securities in which Prospect has invested were acquired in transactions that were exempt from registration under the Securities Act of 1933, as amended (the “Securities Act”). These securities may be resold only in transactions that are exempt from registration under the Securities Act.

[3] Fair value is determined by or under the direction of our Board of Directors. Unless otherwise indicated by endnote 47 below, all of our investments are valued using significant unobservable inputs. In accordance with ASC 820, such investments are classified as Level 3 within the fair value hierarchy. See Notes 2 and 3 within the accompanying notes to consolidated financial statements for further discussion.