Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Expected principal recovery percentage Measurement Input, Expected Principal Recovery Percentage [Member] Measurement Input, Expected Principal Recovery Percentage Investment Owned, At Cost Investment Owned, At Cost [Member] Investment Owned, At Cost Trading Arrangement: Trading Arrangement [Axis] Maximum Maximum [Member] Title of 12(b) Security Subsequent Event Subsequent Event [Member] Adjustment to Compensation, Amount Adjustment to Compensation Amount Financial Instrument [Axis] Financial Instrument [Axis] October 2026 Notes Series A Notes due 2026 October 2026 Notes [Member] October 2026 Notes B-O-F Corporation B-O-F Corporation [Member] B-O-F Corporation Schedule of MSC Income Fund's Investments at Fair Value Hierarchy Fair Value, Assets Measured on Recurring Basis [Table Text Block] Federal Investment Income, Operating, Deferred Federal Tax Expense (Benefit) Investment Income, Operating, Deferred Federal Tax Expense (Benefit) First lien debt Debt Securities, First Lien [Member] Debt Securities, First Lien Affiliate investments: Investment, Affiliated Issuer, Noncontrolled [Member] Other (in dollars per share) Investment Company, Other, Per Share Investment Company, Other, Per Share Escalent, Inc. Escalent, Inc. [Member] Escalent, Inc. Average price (in dollars per share) Shares Acquired, Average Cost Per Share Entity Common Stock, Shares Outstanding Financial Instrument Performance Status [Domain] Financial Instrument Performance Status [Domain] AAC Holdings, Inc. AAC Holdings, Inc. [Member] AAC Holdings, Inc. Ratio of total expenses, including tax expenses, to average NAV (as a percent) Investment Company, Expense Ratio, Including Income Tax Expense Investment Company, Expense Ratio, Including Income Tax Expense SPV Facility SPV Facility [Member] SPV Facility Fee income Fee Income RELATED PARTY TRANSACTIONS Related Party Transactions Disclosure [Text Block] Internet & Catalog Retail Internet And Catalog Retail Sector [Member] Internet And Catalog Retail Sector Federal Funds Rate Federal Funds Rate [Member] Federal Funds Rate Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Number of reportable segments Number of Reportable Segments VVS Holdco LLC VVS Holdco, LLC [Member] VVS Holdco, LLC Health Care Providers & Services Health Care Providers And Services Sector [Member] Health Care Providers And Services Sector Entity Address, City or Town Private Loan portfolio investments Private Loan Portfolio [Member] Private Loan Portfolio Mission Critical Group Mission Critical Group [Member] Mission Critical Group Statement of Financial Position [Abstract] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent) Investment Company, Percentage of Portfolio With Annual Third-Party Appraisal Was Obtained, Reviewed and Certified Investment Company, Percentage of Portfolio With Annual Third-Party Appraisal Was Obtained, Reviewed and Certified Equity Warrant Equity Warrant [Member] Equity Warrant Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Net investment income (in dollars per share) Investment Company, Investment Income (Loss), Per Share, Basic American Nuts, LLC American Nuts, LLC [Member] American Nuts, LLC Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Total Rate Interest rate (as a percent) Weighted-average annual effective yield (as a percent) Investment Interest Rate Floor rate (as a percent) Investment, Interest Rate, Floor O 2025 A2 Regular Dividends O 2026 A2 Regular Dividends [Member] O 2026 A2 Regular Dividends Dividends [Domain] Dividends [Domain] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Implus Footcare, LLC Implus Footcare, LLC [Member] Implus Footcare, LLC Use of Estimates Use of Estimates, Policy [Policy Text Block] Related Party [Axis] Related and Nonrelated Parties [Axis] Repayments on Credit Facilities Repayments of Lines of Credit Construction & Engineering Construction And Engineering Sector [Member] Construction And Engineering Sector Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) Investment Company, Percentage Of Total Investment Income, Attributable To Noncash Paid-in-Kind Interest Income Investment Company, Percentage Of Total Investment Income, Attributable To Noncash Paid-in-Kind Interest Income Document Period End Date Student Resource Center, LLC Student Resource Center, LLC [Member] Student Resource Center, LLC Slick Innovations, LLC Slick Innovations, LLC [Member] Slick Innovations, LLC BDB Holdings, LLC BDB Holdings, LLC [Member] BDB Holdings, LLC Investments Investments, Per Company Investments, Per Company Debt instrument, face amount Debt instrument, par value Debt Instrument, Face Amount Debt instrument effective interest rate (as a percent) Debt Instrument, Interest Rate, Effective Percentage Third-party quote Measurement Input, Third-Party Quote [Member] Measurement Input, Third-Party Quote Advisory Agreement - Incentive Rate, Quarterly Hurdle Rate Advisory Agreement, Incentive Rate, Quarterly Hurdle Rate [Member] Advisory Agreement, Incentive Rate, Quarterly Hurdle Rate Debt instrument, number of extension options Debt Instrument, Number of Extension Options Debt Instrument, Number of Extension Options Entity Shell Company Internet Software & Services Internet Software And Services Sector [Member] Internet Software And Services Sector Number of portfolio investments with investments managers Investment Company, Number Of Portfolio Investments, Investment Managers Investment Company, Number Of Portfolio Investments, Investment Managers SI East, LLC SI East, LLC [Member] SI East, LLC Analytical Systems Keco Holdings, LLC Analytical Systems Keco Holdings, LLC [Member] Analytical Systems Keco Holdings, LLC Other Other Sector [Member] Other Sector Other Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Other Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Other Document Fiscal Period Focus Capital gains incentive fee accrual Incentive Fee Payable, Capital-Gain-Based Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Total liabilities Liabilities Trading Symbol Victory Energy Operations, LLC Victory Energy Operations, LLC [Member] Victory Energy Operations, LLC Flame King Holdings, LLC Flame King Holdings, LLC [Member] Flame King Holdings, LLC Deferred tax expense (benefit): Investment Tax Expense (Income), Deferred [Abstract] Investment Tax Expense (Income), Deferred Strike price (in dollars per share) Option Indexed to Issuer's Equity, Strike Price Ratios to average NAV: Investment Company, Ratio To Average Net Assets [Abstract] Investment Company, Ratio To Average Net Assets Company Selected Measure Name Company Selected Measure Name Sale of Stock [Domain] Sale of Stock [Domain] May 2029 Notes May 2029 Notes [Member] May 2029 Notes Income Tax Disclosure [Abstract] American Health Staffing Group, Inc. American Health Staffing Group, Inc. [Member] American Health Staffing Group, Inc. NET INCREASE IN NET ASSETS RESULTING FROM OPERATIONS PER SHARE—DILUTED (in dollars per share) Investment Company, Investment Income (Loss) from Operations, Per Share, Per Diluted Share Investment Company, Investment Income (Loss) from Operations, Per Share, Per Diluted Share Channel Partners Intermediateco, LLC Channel Partners Intermediateco, LLC [Member] Channel Partners Intermediateco, LLC Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Axis] NET REALIZED GAIN (LOSS): Net Realized Gains (Losses) [Abstract] Net Realized Gains (Losses) Interface Security Systems, L.L.C Interface Security Systems, L.L.C [Member] Interface Security Systems, L.L.C Line of credit facility, commitment fee percentage (as a percent) Line of Credit Facility, Commitment Fee Percentage Credit Facility [Domain] Credit Facility [Domain] CASH FLOWS FROM OPERATING ACTIVITIES Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Total dividends per share (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Wash & Wax Systems LLC Wash & Wax Systems LLC [Member] Wash & Wax Systems LLC Clad-Rex Steel, LLC Chamberlin Holding LLC [Member] Chamberlin Holding LLC Tedder Industries, LLC Tedder Industries, LLC [Member] Tedder Industries, LLC Schedule of Investment Income Investment Income [Table Text Block] Diversified Consumer Services Diversified Consumer Services Sector [Member] Diversified Consumer Services Sector Operating loss carryforwards Operating Loss Carryforwards Dividend payable Dividends Payable MoneyThumb Acquisition, LLC MoneyThumb Acquisition, LLC [Member] MoneyThumb Acquisition, LLC Schedule of MSC Income Fund’s Level 3 Portfolio Investments Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Over $500 million - $1.25 billion Annual Interest Rate Billion [Member] Annual Interest Rate Billion Follow On Public Offering Follow On Public Offering [Member] Follow On Public Offering Investment Company, Financial Highlights [Roll Forward] Investment Company, Financial Highlights [Roll Forward] Award Timing Predetermined Award Timing Predetermined [Flag] Advisory Agreement - Base Management Fees Advisory Agreement - Base Management Fees [Member] Advisory Agreement - Base Management Fees Energy Equipment & Services Energy Equipment And Services Sector [Member] Energy Equipment And Services Sector Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] O 2026 Q2 Supplemental Dividends O 2026 Q2 Supplemental Dividends [Member] O 2026 Q2 Supplemental Dividends Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Roof Opco, LLC Roof Opco, LLC [Member] Roof Opco, LLC O 2026 M10 Dividends O 2026 M10 Dividends [Member] O 2026 M10 Dividends Investment valuation related taxes Investment Tax Expense (Income) [Abstract] Investment Tax Expense (Income) State and other Investment Income, Operating, Deferred State And Other Tax Expense (Benefit) Investment Income, Operating, Deferred State And Other Tax Expense (Benefit) Ratio of net investment income to average NAV (as a percent) Investment Company, Investment Income (Loss) Ratio, Excluding Expense Waivers Investment Company, Investment Income (Loss) Ratio, Excluding Expense Waivers TEC Services, LLC TEC Services, LLC [Member] TEC Services, LLC Boccella Precast Products LLC Boccella Precast Products LLC [Member] Boccella Precast Products LLC Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Iron-Main Investments, LLC Iron-Main Investments, LLC [Member] Iron-Main Investments, LLC Communications Equipment Communications Equipment Sector [Member] Communications Equipment Sector Summary of Investment Holdings [Line Items] Summary of Investment Holdings [Line Items] Total expenses, net of expense waivers Total expenses, net of expense waivers Investment Company, Expense, after Reduction of Fee Waiver and Reimbursement Per Share Data [Abstract] Investment Company, Per Share Data [Abstract] Investment Company, Per Share Data SOFR Adjustment Spread SOFR Adjustment Spread [Member] SOFR Adjustment Spread $0 - $500 million Annual Interest Rate Million [Member] Annual Interest Rate Million Datacom, LLC Compass Systems & Sales, LLC [Member] Compass Systems & Sales, LLC Market comparable / Enterprise value Valuation, Market And Enterprise Value Approach [Member] Valuation, Market And Enterprise Value Approach Concentration Risk Type [Domain] Concentration Risk Type [Domain] Pro-Max Restoration & Paint, LLC Pro-Max Restoration & Paint, LLC [Member] Pro-Max Restoration & Paint, LLC Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Borrowings outstanding Long-Term Line of Credit Total dividends Payments of Ordinary Dividends, Common Stock Expiration Date Trading Arrangement Expiration Date Cash and cash equivalents, Fair Value Cash and Cash Equivalents, Fair Value Disclosure DMA Industries, LLC [Member] DMA Industries, LLC [Member] DMA Industries, LLC Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] NET INVESTMENT INCOME Investment Income, Operating, after Expense and Tax Related Party Transaction [Axis] Related Party Transaction [Axis] Adjustments to reconcile net increase in net assets resulting from operations to net cash used in operating activities: Adjustments To Reconcile Net Assets From Operations To Cash Provided by (Used in) Operating Activities [Abstract] Adjustments To Reconcile Net Assets From Operations To Cash Provided by (Used in) Operating Activities Richardson Sales Solutions Richardson Sales Solutions [Member] Richardson Sales Solutions Event Holdco, LLC Event Holdco, LLC [Member] Event Holdco, LLC Shares outstanding as of the end of the period (in shares) Investment Company, Common Stock, Shares Outstanding Investment Company, Common Stock, Shares Outstanding Investments in and Advances to Affiliates [Table] Investments in and Advances to Affiliates [Table] Debt Variable Rate Component One Debt Variable Rate Component One [Member] Debt Variable Rate Component One DEBT Debt Disclosure [Text Block] Income tax benefit (provision) on net realized gain (loss) and net unrealized appreciation (in dollars per share) Investment​ Company, Income Tax Benefit (Provision), ​​Per​ Share Investment​ Company, Income Tax Benefit (Provision), ​​Per​ Share Deferred financing costs (net of accumulated amortization of $7,692 and $7,259, respectively) Debt Issuance Costs, Net Debt Variable Rate Component [Domain] Debt Variable Rate Component [Domain] Debt Variable Rate Component [Domain] Advisory Agreement - Incentive Rate, Annualized Catch-Up Threshold Advisory Agreement, Incentive Rate, Annualized Catch-Up Threshold [Member] Advisory Agreement, Incentive Rate, Annualized Catch-Up Threshold PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount The Affiliati Network, LLC The Affiliati Network, LLC [Member] The Affiliati Network, LLC IG Investor, LLC IG Investor, LLC [Member] IG Investor, LLC Southwest US Southwest Region [Member] Debt instrument, interest rate, stated percentage (as a percent) Debt Instrument, Interest Rate, Stated Percentage Vitesse Systems Vitesse Systems [Member] Vitesse Systems Total net assets Balance at beginning of period Balance at ending of period NAV as of the end of the period Equity, Attributable to Parent ASSETS Assets [Abstract] EBITDA multiple Measurement Input, EBITDA Multiple [Member] Taxable income earned in prior year and carried forward for distribution in current year Investment Company, Tax Basis, Taxable Income Earned in Prior Year and Carried Forward for Distribution in Current Year Investment Company, Tax Basis Reconciliation, Taxable Income Earned in Prior Year and Carried Forward for Distribution in Current Year Infinity X1 Holdings, LLC Infinity X1 Holdings, LLC [Member] Infinity X1 Holdings, LLC Insider Trading Policies and Procedures [Line Items] Investment, Issuer Affiliation [Domain] Investment, Issuer Affiliation [Domain] Nonperforming Financial Instruments Nonperforming Financial Instruments [Member] Deferred taxes Deferred Income Tax Expense (Benefit) Debt instrument, extension option term Debt Instrument, Extension Option Term Debt Instrument, Extension Option Term Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) Investment Company, Percentage Of Total Investment Income, Attributable To Interest Income, Debt Investments, Net Investment Company, Percentage Of Total Investment Income, Attributable To Interest Income, Debt Investments, Net Entity Central Index Key Equity [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] DIVIDENDS, DISTRIBUTIONS AND TAXABLE INCOME Dividend, Distributions, Income Tax Disclosure [Text Block] Dividend, Distributions, Income Tax Disclosure BP Loenbro Holdings Inc. BP Loenbro Holdings Inc. [Member] BP Loenbro Holdings Inc. Investment, term Investment, Term Investment, Term O 2026 Q4 Supplemental Dividends O 2026 Q4 Supplemental Dividends [Member] O 2026 Q4 Supplemental Dividends Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Dividend Revenue Recognition, Dividends [Policy Text Block] Share Repurchase Program [Table] Share Repurchase Program [Table] Schedule of Provision for Income Taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Initial Public Offering Initial Public Offering [Member] Initial Public Offering Second lien debt Debt Securities, Second Lien [Member] Debt Securities, Second Lien Total net unrealized appreciation (depreciation) Net unrealized appreciation Amount of Unrealized Gain/(Loss) Debt and Equity Securities, Unrealized Gain (Loss) Debt instrument, basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Variable Rate [Domain] Variable Rate [Domain] All Individuals All Individuals [Member] Investment, Issuer Name [Domain] Investment, Issuer Name [Domain] MonitorUS Holding, LLC MonitorUS Holding, LLC [Member] MonitorUS Holding, LLC Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Total net realized gain (loss) Net realized (gain) loss Amount of Realized Gain/(Loss) Debt and Equity Securities, Realized Gain (Loss) Statement [Line Items] Statement [Line Items] Total assets Assets Annual revenues Investments, Annual Revenues Per Company Investments, Annual Revenues Per Company Interest Interest Expense, Operating MSC Income MSC Income [Member] MSC Income Industry Sector [Axis] Industry Sector [Axis] Investments in and Advances to Affiliates [Abstract] PEO PEO [Member] Additional Other Portfolio investment Investment Company, Number Of Additional Investments, Commitments Restricted For Fund Expenses Or Follow On Investments In Existing Portfolio Investment Company, Number Of Additional Investments, Commitments Restricted For Fund Expenses Or Follow On Investments In Existing Portfolio Schedule of Outstanding Commitments Investment Company, Outstanding Capital Commitments [Table Text Block] Investment Company, Outstanding Capital Commitments Logix Acquisition Company, LLC Logix Acquisition Company, LLC [Member] Logix Acquisition Company, LLC Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Gamber-Johnson Holdings, LLC Gamber-Johnson Holdings, LLC [Member] Gamber-Johnson Holdings, LLC Total Overdistributed Earnings Retained Earnings [Member] O 2026 A2 Supplemental Dividends O 2026 A2 Supplemental Dividends [Member] O 2026 A2 Supplemental Dividends Money market funds Money Market Funds [Member] Revolving Credit Facility Revolving Credit Facility [Member] Fair Value Hierarchy Fair Value Measurement, Policy [Policy Text Block] Net increase in net assets resulting from operations (in dollars per share) Investment Company, Investment Income (Loss) from Operations, Per Share Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock, shares outstanding (in shares) Balance at beginning of period (in shares) Balance at ending of period (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Nello Industries Investco, LLC Nello Industries Investco, LLC [Member] Nello Industries Investco, LLC Prepaid and other assets Increase (Decrease) in Prepaid Expense and Other Assets Investment company, number of companies within portfolio excluded from EBITDA calculation Investment Company, Number of Companies Within Portfolio Excluded From EBITDA Calculation Investment Company, Number of Companies Within Portfolio Excluded From EBITDA Calculation GradeEight Corp. GradeEight Corp. [Member] GradeEight Corp. Interest income Interest Income, Operating, Paid in Cash Microbe Formulas, LLC Microbe Formulas, LLC [Member] Microbe Formulas, LLC LMM portfolio investments Lower Middle Market Portfolio [Member] Lower Middle Market Portfolio JTI Electrical & Mechanical, LLC JTI Electrical & Mechanical, LLC [Member] JTI Electrical & Mechanical, LLC Federal Realized Gain (Loss), Investment And Derivative, Operating, Deferred Federal Tax Expense (Benefit) Realized Gain (Loss), Investment And Derivative, Operating, Deferred Federal Tax Expense (Benefit) Total investment return (as a percent) Investment Company, Total Return, Market Value Percentage of total investment income, attributable to noncash cumulative dividend income (as a percent) Investment Company, Percentage Of Total Investment Income, Attributable To Noncash Cumulative Dividend Income Investment Company, Percentage Of Total Investment Income, Attributable To Noncash Cumulative Dividend Income Common stock repurchased Common stock repurchased Stock Repurchased During Period, Value O 2026 Q2 Regular Dividends O 2026 Q2 Regular Dividends [Member] O 2026 Q2 Regular Dividends Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Share Repurchase Program [Line Items] Share Repurchase Program [Line Items] Percentage of portfolio investments containing limited consultation with financial advisory services firm (as a percent) Investment Company, Portfolio Investments, Limited Consultation With Financial Advisory Services Firm, Percentage Investment Company, Portfolio Investments, Limited Consultation With Financial Advisory Services Firm, Percentage Over-Allotment Option Over-Allotment Option [Member] Interest payable Increase (Decrease) in Interest Payable, Net State and other Investment Income, Operating, State And Other Tax Expense (Benefit), Current Investment Income, Operating, State And Other Tax Expense (Benefit), Current Middle Market portfolio investments Middle Market Portfolio [Member] Middle Market Portfolio O 2025 Q2 Supplemental Dividends O 2025 Q2 Supplemental Dividends [Member] O 2025 Q2 Supplemental Dividends Investment, Issuer Name [Axis] Investment, Issuer Name [Axis] Hornblower Sub, LLC Hornblower Sub, LLC [Member] Hornblower Sub, LLC Value of shares issued pursuant to the dividend reinvestment plan Stock Issued Sale of Stock [Axis] Sale of Stock [Axis] Risk adjusted discount factor, outlier Measurement Input, Risk Adjusted Discount Factor, Outlier [Member] Measurement Input, Risk Adjusted Discount Factor, Outlier Schedule of Dividends Payable Dividends Declared [Table Text Block] ATS Operating, LLC ATS Operating, LLC [Member] ATS Operating, LLC Media Media Sector [Member] Media Sector Dividend income Investment Income, Dividend Auria Space, LLC Auria Space, LLC [Member] Auria Space, LLC Related Party Transaction [Domain] Related Party Transaction [Domain] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Investments at fair value Fair value Total Level 3 investments Beginning balance Ending balance Investment Owned, Fair Value Equity investments Equity Equity Securities [Member] UserZoom Technologies, Inc. UserZoom Technologies, Inc. [Member] UserZoom Technologies, Inc. Internal administrative services expenses Administrative Fees Expense Common stock, shares issued (in shares) Common Stock, Shares, Issued Beginning balance Ending balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Consolidated Schedule of Investments In and Advances to Affiliates Investments in and Advances to Affiliates, Schedule of Investments [Text Block] CRC Evans USA Bidco, Inc. CRC Evans USA Bidco, Inc. [Member] CRC Evans USA Bidco, Inc. Accretive effect of stock repurchases (repurchasing shares below NAV per share) (in dollars per share) Investment Company, Share Repurchase, Per Share Cash balances exceeded federal deposit insurance corporation insurance protection levels Cash, Uninsured Amount Class of Stock [Line Items] Class of Stock [Line Items] Amount of Interest, Fees or Dividends Credited to Income Interest, Fees and Dividend Income, Securities, Operating Interest, Fees and Dividend Income, Securities, Operating Deferred tax liability, net Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Termination Date Trading Arrangement Termination Date Advisory Agreement - Incentive Fees, Capital Gains Fees Advisory Agreement - Incentive Fees, Capital Gains Fees [Member] Advisory Agreement - Incentive Fees, Capital Gains Fees Dividend payable as of period end and paid in the following period Investment Company, Tax Basis, Dividends Paid Or Payable Investment Company, Tax Basis, Dividends Paid Or Payable Subsequent Events [Abstract] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Elgin AcquireCo, LLC Elgin AcquireCo, LLC [Member] Elgin AcquireCo, LLC Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Orttech Holdings, LLC Orttech Holdings, LLC [Member] Orttech Holdings, LLC Transfers Into (Out of) Level 3 Hierarchy Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net Fair Value as of Grant Date Award Grant Date Fair Value Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified Investment Company, Number Of Portfolio Companies With Annual Third-Party Appraisal Was Obtained, Reviewed and Certified Investment Company, Number Of Portfolio Companies With Annual Third-Party Appraisal Was Obtained, Reviewed and Certified Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] HDC/HW Intermediate Holdings HDC/HW Intermediate Holdings [Member] HDC/HW Intermediate Holdings Arrangement Duration Trading Arrangement Duration Island Pump and Tank, LLC Island Pump and Tank, LLC [Member] Island Pump and Tank, LLC Debt instrument, interest rate, below investment grade rating, stated percentage (as a percent) Debt Instrument, Interest Rate, Below Investment Grade Rating, Stated Percentage Debt Instrument, Interest Rate, Below Investment Grade Rating, Stated Percentage Entity Address, Postal Zip Code Entity Registrant Name Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Ratio of operating expenses, excluding interest expense and incentive fees, to average NAV (as a percent) Investment Company, Operating Expenses Ratio, Excluding Interest Expense, Incentive Fees And Expense Waivers Investment Company, Operating Expenses Ratio, Excluding Interest Expense, Incentive Fees And Expense Waivers Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Interest PIK income Interest Income, Operating, Paid in Kind Winter Services LLC Winter Services LLC [Member] Winter Services LLC All Award Types Award Type [Domain] Net realized gain (loss) (in dollars per share) Investment Company, Realized Gain (Loss) on Investment, Per Share Net investment income taxes Net Investment Income Tax Expense (Benefit) [Abstract] Net Investment Income Tax Expense (Benefit) FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION Fair Value Disclosures [Text Block] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Units (as a percent) Investment Owned, Balance, Percent Of Shares Investment Owned, Balance, Percent Of Shares Geographical [Axis] Geographical [Axis] Line of credit facility, maximum borrowing capacity including accordion feature Line of Credit Facility, Maximum Borrowing Capacity Including Accordion Feature Line of Credit Facility, Maximum Borrowing Capacity Including Accordion Feature Investment, Issuer Affiliation [Axis] Investment, Issuer Affiliation [Axis] Schedule of Annual Basis Point Rate Annual Basis Point Rate Table Text Block [Table Text Block] Annual Basis Point Rate Table Text Block Annual Interest Rate [Axis] Annual Interest Rate [Axis] Annual Interest Rate Legal Entity [Axis] State and other Realized Gain (Loss), Investment And Derivative, Operating, Deferred State And Other Tax Expense (Benefit) Realized Gain (Loss), Investment And Derivative, Operating, Deferred State And Other Tax Expense (Benefit) CoreStack, Inc. CoreStack, Inc. [Member] CoreStack, Inc. Total Interest Expense Interest Expense, Debt West US West Region [Member] Fee Income Management and Investment Advisory Fees, Policy [Policy Text Block] NET INCREASE IN NET ASSETS RESULTING FROM OPERATIONS PER SHARE—BASIC (in dollars per share) Investment Company, Investment Income (Loss) from Operations, Per Share, Per Basic Share Investment Company, Investment Income (Loss) from Operations, Per Share, Per Basic Share CASH AND CASH EQUIVALENTS AS OF BEGINNING OF PERIOD CASH AND CASH EQUIVALENTS AS OF END OF PERIOD Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation CenterPeak Holdings, LLC CenterPeak Holdings, LLC [Member] CenterPeak Holdings, LLC Income tax provision Investment Company, Tax Basis, Income Tax Provision Investment Company, Tax Basis, Income Tax Provision Achieved total return on investments Investment Company, Achieved Total Return Investment Company, Achieved Total Return Non-NEOs Non-NEOs [Member] AGS American Glass Services Acquisition, LLC AGS American Glass Services Acquisition, LLC [Member] AGS American Glass Services Acquisition, LLC Interest and dividend receivable Interest and Dividend Receivable Interest and Dividend Receivable Food & Staples Retailing Food And Staples Retailing Sector [Member] Food And Staples Retailing Sector Schedule of Debt and Average Amount of Total Borrowings Outstanding and Weighted-Overall Average Effective Interest Rate Schedule of Debt [Table Text Block] South Coast Terminals Holdings, LLC South Coast Terminals Holdings, LLC [Member] South Coast Terminals Holdings, LLC Long-Term Debt, Type [Domain] Long-Term Debt, Type [Domain] Federal and state income and other tax expenses Investment Company, Federal And State Income And Other Tax Expense Investment Company, Federal And State Income And Other Tax Expense Rug Doctor, LLC. Rug Doctor, LLC. [Member] Rug Doctor, LLC. Redemption of common stock Payments for Repurchase of Common Stock Statistical Measurement [Axis] Statistical Measurement [Axis] Base fee rate (as a percent) Management and Service Fees, Base Rate Award Type Award Type [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Total overdistributed earnings Retained Earnings (Accumulated Deficit) Purchase Commitments Purchase Commitments [Member] Purchase Commitments Northeast US Northeast Region [Member] Summary of Investment Holdings [Table] Investment Holdings [Table] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Common Stock Common Stock [Member] Advisory Agreement - Incentive Rate, Pre-Incentive Fee Net Investment Income Exceeds Catch-Up Threshold Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Exceeds Catch-Up Threshold [Member] Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Exceeds Catch-Up Threshold Air Freight & Logistics Air Freight And Logistics Sector [Member] Air Freight And Logistics Sector Other Non-U.S. Non-US [Member] Current tax expense (benefit): Current Federal, State and Local, Tax Expense (Benefit) [Abstract] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Total liabilities and net assets Liabilities and Equity DIVIDEND REINVESTMENT PLAN Stockholders' Equity, Dividend Reinvestment Plan [Text Block] Stockholders' Equity, Dividend Reinvestment Plan Employee Stock Option Share-Based Payment Arrangement, Option [Member] New Investments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases PrimeFlight Aviation Services PrimeFlight Aviation Services [Member] PrimeFlight Aviation Services Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Asset Class [Axis] Asset Class [Axis] Related Party [Domain] Related and Nonrelated Parties [Domain] Tabular List, Table Tabular List [Table Text Block] Additional paid-in capital Additional Paid in Capital Name Awards Close in Time to MNPI Disclosures, Individual Name Investment, Identifier [Axis] Investment, Identifier [Axis] Machinery Machinery Sector [Member] Machinery Sector Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Market approach Valuation, Market Approach [Member] Sale of stock (in dollars per share) Sale of Stock, Price Per Share Adjustment to Compensation: Adjustment to Compensation [Axis] Digital Products Holdings LLC Datacom, LLC [Member] Datacom, LLC Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activity Credit Facility [Axis] Credit Facility [Axis] Name Measure Name Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Net Realized Gains or Losses and Net Unrealized Appreciation or Depreciation Net Realized Gains Or Losses and Net Unrealized Appreciation Or Depreciation [Policy Text Block] Net Realized Gains Or Losses and Net Unrealized Appreciation Or Depreciation NuStep, LLC NuStep, LLC [Member] NuStep, LLC Debt Instrument [Line Items] Debt Instrument [Line Items] Additional Paid-In Capital Additional Paid-in Capital [Member] Name Trading Arrangement, Individual Name Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income [Member] Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Cash and cash equivalents Cash and cash equivalent, Cost Cash and Cash Equivalent IG Parent Corporation IG Parent Corporation [Member] IG Parent Corporation Company Selected Measure Amount Company Selected Measure Amount Interest and dividend receivable Increase (Decrease) In Interest And Dividend Receivable Increase (Decrease) In Interest And Dividend Receivable SOFR Secured Overnight Financing Rate (SOFR) [Member] SPAU Holdings, LLC SPAU Holdings, LLC [Member] SPAU Holdings, LLC O 2026 M12 Dividends O 2026 M12 Dividends [Member] O 2026 M12 Dividends Net unrealized appreciation Investment Company, Tax Basis, Unrealized (Gain) Loss, Not Currently (Taxable) Deductible Non-PEO NEO Non-PEO NEO [Member] EXPENSES: Interest and Debt Expense [Abstract] Subsidiary, Sale of Stock [Line Items] Subsidiary, Sale of Stock [Line Items] Main Street Facility Main Street Facility [Member] Main Street Facility Total net investment income tax provision Investment Income, Operating, Tax Expense (Benefit) Waiver of incentive fee on income Investment Company, Incentive Fee Waived, Income-Based Award Timing Method Award Timing Method [Text Block] Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] O 2025 A2 Regular Dividends O 2025 A2 Regular Dividends [Member] O 2025 A2 Regular Dividends NET INCREASE IN NET ASSETS RESULTING FROM OPERATIONS Net increase in net assets resulting from operations Net increase in net assets resulting from operations Net increase in net assets resulting from operations Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Investments Investments [Member] Schedule of Management And Incentive Fee Management And Incentive Fee [Table Text Block] Management And Incentive Fee Garyline, LLC Garyline, LLC [Member] Garyline, LLC Restatement Determination Date: Restatement Determination Date [Axis] Buca C, LLC Buca C, LLC [Member] Buca C, LLC AVEX Aviation Holdings, LLC AVEX Aviation Holdings, LLC [Member] AVEX Aviation Holdings, LLC Excise tax expense Excise Investment Company, Excise Tax Expense (Benefit) Investment Company, Excise Tax Expense (Benefit) Jackmont Hospitality, Inc. Jackmont Hospitality, Inc. [Member] Jackmont Hospitality, Inc. Southeast US Southeast Region [Member] Average EBITDA Investment Company, Average Earnings Before Interest, Taxes, Depreciation, And Amortization Investment Company, Average Earnings Before Interest, Taxes, Depreciation, And Amortization Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Debt Variable Rate Component [Axis] Debt Variable Rate Component [Axis] Debt Variable Rate Component Statistical Measurement [Domain] Statistical Measurement [Domain] Document Fiscal Year Focus Common stock, $0.001 par value per share (450,000,000 shares authorized; 45,345,229 and 46,588,608 shares issued and outstanding, respectively) Common Stock, Value, Issued Schedule of Investments in and Advances to Affiliates, Schedule of Investments Schedule of Investments in and Advances to Affiliates, Schedule of Investments [Table Text Block] Line of Credit Line of Credit [Member] Restatement Determination Date Restatement Determination Date Hawk Ridge Systems, LLC Hawk Ridge Systems, LLC [Member] Hawk Ridge Systems, LLC Income tax benefit (provision) on net realized gain (loss) and net unrealized appreciation (depreciation) Total investment valuation related income tax provision (benefit) Realized Gain (Loss), Investment and Derivative, Operating, Tax Expense (Benefit) Non‑Control/Non‑Affiliate investments: Investment, Unaffiliated Issuer [Member] MSC Income Fund Rule 10b5-1 Stock Repurchase Plan MSC Income Fund Rule 10b5-1 Stock Repurchase Plan [Member] MSC Income Fund Rule 10b5-1 Stock Repurchase Plan MCT Purchaserco Holding Inc. MCT Purchaserco Holding Inc. [Member] MCT Purchaserco Holding Inc. Amendment Flag Accounts payable and other liabilities Increase (Decrease) in Accounts Payable and Other Operating Liabilities NET INVESTMENT INCOME BEFORE TAXES Net Investment Income Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Below Catch-Up Threshold Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Below Catch-Up Threshold [Member] Advisory Agreement, Incentive Rate, Pre-Incentive Fee Net Investment Income Below Catch-Up Threshold Pre-tax book income not consolidated for tax purposes Investment Company, Tax Basis, Pre-tax Book (Income) Loss Not Consolidated For Tax purposes, Increase (Decrease) In Taxable Income Investment Company, Tax Basis, Pre-tax Book (Income) Loss Not Consolidated For Tax purposes, Increase (Decrease) In Taxable Income Investments [Domain] Investments [Domain] Diversified Financial Services Diversified Financial Services Sector [Member] Diversified Financial Services Sector Direct Marketing Solutions, Inc. Digital Products Holdings LLC [Member] Digital Products Holdings LLC JorVet Holdings, LLC JorVet Holdings, LLC [Member] JorVet Holdings, LLC Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Entity Address, State or Province Auto Components Auto Components Sector [Member] Auto Components Sector PEO Total Compensation Amount PEO Total Compensation Amount Commercial Services & Supplies Commercial Services And Supplies Sector [Member] Commercial Services And Supplies Sector Share Repurchase Program [Domain] Share Repurchase Program [Domain] WEIGHTED-AVERAGE SHARES OUTSTANDING—BASIC (in shares) Weighted Average Number of Shares Outstanding, Basic Ratio of operating expenses, excluding interest expense, to average NAV (as a percent) Investment Company, Operating Expenses Ratio, Excluding Interest Expense and Expense Waivers Investment Company, Operating Expenses Ratio, Excluding Interest Expense and Expense Waivers Ignite Visibility LLC Ignite Visibility LLC [Member] Ignite Visibility LLC Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Schedule of Investments [Abstract] Median Median [Member] Obra Capital, Inc. Obra Capital, Inc. [Member] Obra Capital, Inc. Ratio of operating expenses, excluding interest expense and incentive fees, net of waivers, to average NAV (as a percent) Investment Company, Operating Expenses Ratio Excluding Interest Expense and Incentive Fees Investment Company, Operating Expenses Ratio Excluding Interest Expense and Incentive Fees Weighted-average debt outstanding Average outstanding debt Long-Term Debt, Average Amount Outstanding Interest rate, stated (as a percent) Investment Interest Rate, Stated Investment Interest Rate, Stated Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Industry Concentration Risk Industry Concentration Risk [Member] Industry Concentration Risk Unearned Income—Debt Origination Fees and Original Issue Discount and Discounts / Premiums to Par Value Unearned Income [Policy Text Block] Unearned Income Brewer Crane Holdings, LLC Bettercloud, Inc. [Member] Bettercloud, Inc. Dividends paid Payments of Ordinary Dividends Dividend reinvestment Value of shares issued in DRIP participation Stock Issued During Period, Value, Dividend Reinvestment Plan Gross Reductions Investments in and Advances to Affiliates, at Fair Value, Gross Reductions Annual Interest Rate [Domain] Annual Interest Rate [Domain] Annual Interest Rate [Domain] Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Subsidiary or Equity Method Investee, Sale of Stock, Type [Table] Subsidiary or Equity Method Investee, Sale of Stock, Type [Table] O 2026 M11 Dividends O 2026 M11 Dividends [Member] O 2026 M11 Dividends Investment Type Concentration Risk Investment Type Concentration Risk [Member] Investment Type Concentration Risk FCC Intermediate Holdco, LLC FCC Intermediate Holdco, LLC [Member] FCC Intermediate Holdco, LLC Total expenses before expense waivers Investment Income, Investment Expense Recently Issued or Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Joerns Healthcare, LLC Joerns Healthcare, LLC [Member] Joerns Healthcare, LLC Amortization of deferred financing costs Amortization of Debt Issuance Costs Dividend Reinvestment Plan Dividend Reinvestment Plan [Member] Dividend Reinvestment Plan Unsecured Debt Unsecured Debt [Member] O 2026 Q4 Dividends O 2026 Q4 Dividends [Member] O 2026 Q4 Dividends Schedule of Investment Holdings Summary Investment Holdings [Table Text Block] Dividend reinvestment (in shares) Shares issued for DRIP (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan Debt Recorded Value Long-Term Debt Average NAV Investment Company, Average Net Assets Other Portfolio investments Other Other Security Investments [Member] Dilutive effect of stock offerings (issuing shares below NAV per share) (in dollars per share) Investment Company, Effect of Stock Offerings, Per Share Investment Company, Effect of Stock Offerings, Per Share Changes in other assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Security Exchange Name Capital gains incentive fee accrual Increase (Decrease) in Incentive Fee Accrual, Capital-Gain-Based Increase (Decrease) in Incentive Fee Accrual, Capital-Gain-Based Total deferred tax expense (benefit) Realized Gain (Loss), Investment And Derivative, Operating, Deferred Tax Expense (Benefit) Realized Gain (Loss), Investment And Derivative, Operating, Deferred Tax Expense (Benefit) Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] ITA Holdings Group, LLC ITA Holdings Group, LLC [Member] ITA Holdings Group, LLC Segments Segment Reporting, Policy [Policy Text Block] Airo Purchaser, Inc. Airo Purchaser, Inc. [Member] Airo Purchaser, Inc. Colonial Electric Company LLC Cody Pools, Inc. [Member] Cody Pools, Inc. Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Marine Marine Sector [Member] Marine Sector Debt Variable Rate Component Two Debt Variable Rate Component Two [Member] Debt Variable Rate Component Two Invincible Boat Company, LLC. Invincible Boat Company, LLC. [Member] Invincible Boat Company, LLC. Insight Borrower Corporation Insight Borrower Corporation [Member] Insight Borrower Corporation Aerospace & Defense Aerospace And Defense Sector [Member] Aerospace And Defense Sector Geographical [Domain] Geographical [Domain] Schedule of Interest Expense Interest Income and Interest Expense Disclosure [Table Text Block] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Number of portfolio companies Investment Company, Number Of Portfolio Companies Investment Company, Number Of Portfolio Companies Textiles, Apparel & Luxury Goods Textiles, Apparel And Luxury Goods Sector [Member] Textiles, Apparel And Luxury Goods Sector Schedule of Investments [Table] Schedule of Investments [Table] U.S. TelePacific Corp. U.S. TelePacific Corp. [Member] U.S. TelePacific Corp. Kickhaefer Manufacturing Company, LLC Kickhaefer Manufacturing Company, LLC [Member] Kickhaefer Manufacturing Company, LLC Non-cash financing activities: Noncash Investing and Financing Items [Abstract] Outstanding Balance Long-Term Debt, Gross Metalforming Holdings, LLC Metalforming Holdings, LLC [Member] Metalforming Holdings, LLC Debt investments Debt Debt Securities [Member] Asset Class [Domain] Asset Class [Domain] Related Party Transactions [Abstract] KMS, LLC KMS, LLC [Member] KMS, LLC Volusion, LLC Volusion, LLC [Member] Volusion, LLC Deferred Financing Costs Debt, Policy [Policy Text Block] Chamberlin Holding LLC Centre Technologies Holdings, LLC [Member] Centre Technologies Holdings, LLC Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] WEIGHTED-AVERAGE SHARES OUTSTANDING—DILUTED (in shares) Weighted Average Number of Shares Outstanding, Diluted Dividends paid from net investment income (in dollars per share) Investment Company, Dividend Distribution to Shareholders, Per Share Investment Company, Dividend Distribution to Shareholders, Per Share Entity Emerging Growth Company Related Party Transaction [Line Items] Related Party Transaction [Line Items] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Horwitz Holdings, LLC Horwitz Holdings, LLC [Member] Horwitz Holdings, LLC Equity Offering Costs Equity Offering Costs [Policy Text Block] Equity Offering Costs Proceeds from Credit Facilities Proceeds from Lines of Credit Net assets, percentage (as a percent) Investments in and Advances to Affiliates, Percentage Of Net Assets Investments in and Advances to Affiliates, Percentage Of Net Assets Watterson Brands, LLC Watterson Brands, LLC [Member] Watterson Brands, LLC Cash equivalents Cash Equivalent, Money Market Fund, Carrying Value World Micro Holdings, LLC World Micro Holdings, LLC [Member] World Micro Holdings, LLC Purchase of stock at the public offering price (in dollars per share) Investment Company, Purchase Of Stock At The Public Offering Price, Per Share Investment Company, Purchase Of Stock At The Public Offering Price, Per Share Hotels, Restaurants & Leisure Hotels, Restaurants And Leisure Sector [Member] Hotels, Restaurants And Leisure Sector Titan Meter Midco Corp. Titan Meter Midco Corp. [Member] Titan Meter Midco Corp. Organization, Consolidation and Presentation of Financial Statements [Abstract] Ratio of operating expenses to average NAV (as a percent) Investment Company, Operating Expenses Ratio Investment Company, Operating Expenses Ratio Ratio of net investment income to average NAV (as a percent) Investment Company, Investment Income (Loss) Ratio Beverages Beverages Sector [Member] Beverages Sector Interest rate (as a percent) Investment, Index Based Floating Interest Rate Investment, Index Based Floating Interest Rate Incentive fee on income Incentive fee on income Incentive Fee Expense, Income-Based All Executive Categories All Executive Categories [Member] Federal Investment Income, Operating, Federal Tax Expense (Benefit), Current Investment Income, Operating, Federal Tax Expense (Benefit), Current WACC Measurement Input, Weighted-Average Cost Of Capital [Member] Measurement Input, Weighted-Average Cost Of Capital Valuation Approach and Technique [Domain] Valuation Approach and Technique 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Common Stock, Shares Authorized Sale of stock, number of shares (in shares) Sale of Stock, Number of Shares Issued in Transaction Incentive fee on capital gains Incentive fee on capital gains Incentive Fee Expense, Capital-Gain-Based, Reversal Incentive Fee Expense, Capital-Gain-Based, Reversal Exercise Price Award Exercise Price Share repurchase program, authorized, amount Share Repurchase Program, Authorized, Amount Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] O 2025 Q2 Regular Dividends O 2025 Q2 Regular Dividends [Member] O 2025 Q2 Regular Dividends Measurement input Investment Company, Investment Owned, Measurement Input Investment, cost Cost Investment Owned, Cost Gross Additions Investments in and Advances to Affiliates, at Fair Value, Gross Additions Interest payable Interest Payable Base management fee Base management fee Management Fee Expense Unamortized debt issuance costs Unamortized debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net GRT Rubber Technologies LLC GRT Rubber Technologies LLC [Member] GRT Rubber Technologies LLC Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] FINANCIAL HIGHLIGHTS Investment Company, Financial Highlights [Text Block] Equity Component [Domain] Equity Component [Domain] Gain (loss) included in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Measurement Input Type [Domain] Measurement Input Type [Domain] Isagenix International, LLC Isagenix International, LLC [Member] Isagenix International, LLC INVESTMENT INCOME: Investment Income, Net [Abstract] Base management and incentive fees payable Increase (Decrease) in Management and 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CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Centre Technologies Holdings, LLC Brewer Crane Holdings, LLC [Member] Brewer Crane Holdings, LLC Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Weighted Average Weighted-Average Weighted Average [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Ratio of total expenses, including tax expenses, to average NAV (as a percent) Investment Company, Expense Ratio, Including Income Tax Expense, Excluding Expense Waivers Investment Company, Expense Ratio, Including Income Tax Expense, Excluding Expense Waivers Advisory Agreement - Incentive Rate, Annualized Hurdle Rate Advisory Agreement, Incentive Rate, Annualized Hurdle Rate [Member] Advisory Agreement, Incentive Rate, Annualized Hurdle Rate Income Taxes Income Tax, Policy [Policy Text Block] Net cash used in operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Advisory Agreement - Incentive Rate, Quarterly Catch-Up Threshold Advisory Agreement, Incentive Rate, Quarterly Catch-Up Threshold [Member] Advisory Agreement, Incentive Rate, Quarterly Catch-Up Threshold Total income tax provision Investment Company, Income Tax Expense (Benefit) Investment Company, Income Tax Expense (Benefit) Royal Cup Inc. Royal Cup Inc. [Member] Royal Cup Inc. Number of components related to incentive fee Related Party Transaction, Number Of Components Related to Incentive Fee Related Party Transaction, Number Of Components Related to Incentive Fee Income Statement [Abstract] NET ASSETS Equity, Attributable to Parent [Abstract] Document Transition Report Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Spread (as a percent) Spread Investment, Basis Spread, Variable Rate City Area Code Computer Data Source, LLC Computer Data Source, LLC [Member] Computer Data Source, LLC Geographic Concentration Risk Geographic Concentration Risk [Member] SUBSEQUENT EVENTS Subsequent Events [Text Block] Estimated fair value Debt Instrument, Fair Value Disclosure Name Forgone Recovery, Individual Name Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Entity [Domain] Market value as of the end of the period (in dollars per share) Investment Company, Market Value, Per Share Consultation period subsequent to initial investment Investment Company, Consultation Period Subsequent to Initial Investment Investment Company, Consultation Period Subsequent to Initial Investment Main Street Main Street [Member] Main Street Accounts payable and other liabilities Accounts Payable and Other Accrued Liabilities Net deferred tax liabilities Deferred Tax Liabilities, Net Issuances of common stock, net of underwriting and offering costs (in shares) Stock Issued During Period, Shares, New Issues Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Share repurchase program, percentage of outstanding stock maximum Share Repurchase Program, Percentage of Outstanding Stock Maximum Share Repurchase Program, Percentage of Outstanding Stock Maximum Principal Investment Owned, Balance, Principal Amount Computers & Peripherals Computers And Peripherals Sector [Member] Computers And Peripherals Sector Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Total deferred tax expense Investment Income, Operating, Deferred Tax Expense (Benefit) Investment Income, Operating, Deferred Tax Expense (Benefit) Schedule of Taxable Income and to Total Distributions Declared to Common Stock Reconciliation Federal Income Tax Note [Table Text Block] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Annualized total return on investments Investment Company, Annualized Total Return Investment Company, Annualized Total Return Estimated taxable income Investment Company, Tax Basis, Net Income (Loss) Attributable To Parent, Estimated Investment Company, Tax Basis, Net Income (Loss) Attributable To Parent, Estimated Investment Company [Abstract] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Schedule of Fair Value Measurement Inputs and Valuation Techniques Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Interest Revenue Recognition, Interest [Policy Text Block] Entity Current Reporting Status Net cash provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Control investments: Investment, Affiliated Issuer, Controlled [Member] Total Shareholder Return Amount Total Shareholder Return Amount Trantech Radiator Topco, LLC Trantech Radiator Topco, LLC [Member] Trantech Radiator Topco, LLC Total return based on change in NAV (as a percent) Investment Company, Total Return Chemicals Chemicals Sector [Member] EBITDA multiple, outlier Measurement Input, EBITDA Multiple, Outlier [Member] Measurement Input, EBITDA Multiple, Outlier ArborWorks, LLC ArborWorks, LLC [Member] ArborWorks, LLC CASH FLOWS FROM FINANCING ACTIVITIES Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Line of credit facility, unused capacity, commitment fee percentage (as a percent) Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Financial Instruments [Domain] Financial Instruments [Domain] Integral Energy Services Integral Energy Services [Member] Integral Energy Services Dynamic Communities, LLC Dynamic Communities, LLC [Member] Dynamic Communities, LLC Underlying Securities Award Underlying Securities Amount Issuances of common stock, net of underwriting and offering costs Stock Issued During Period, Value, New Issues Schedule of Financial Highlights of MSC Income Fund Investment Company, Financial Highlights [Table Text Block] Mills Fleet Farm Group, LLC Mills Fleet Farm Group, LLC [Member] Mills Fleet Farm Group, LLC Specialty Retail Specialty Retail Sector [Member] Specialty Retail Sector Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] GFG Group, LLC GFG Group, LLC [Member] GFG Group, LLC Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Current Fiscal Year End Date Shares acquired (in shares) Units (in shares) Investment Owned, Balance, Shares Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Common stock repurchased (in shares) Total number of shares purchased as part of publicly announced plans or programs (in shares) Stock Repurchased During Period, Shares Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Cash dividend (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Bond Brand Loyalty ULC Bond Brand Loyalty ULC [Member] Bond Brand Loyalty ULC Bluestem Brands, Inc. Bluestem Brands, Inc. [Member] Bluestem Brands, Inc. Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Risk adjusted discount factor Measurement Input, Risk Adjusted Discount Factor [Member] Measurement Input, Risk Adjusted Discount Factor CQ Fluency, LLC CQ Fluency, LLC [Member] CQ Fluency, LLC Measure: Measure [Axis] Proceeds from sales and return of capital of equity investments in portfolio companies Proceeds From Sales And Return Of Capital Of Equity Investments In Portfolio Companies Proceeds From Sales And Return Of Capital Of Equity Investments In Portfolio Companies Coregistics Buyer LLC Coregistics Buyer LLC [Member] Coregistics Buyer LLC Equity Components [Axis] Equity Components [Axis] Related Party Related Party [Member] Entity Interactive Data Current Variable Rate [Axis] Variable Rate [Axis] Batjer TopCo, LLC Batjer TopCo, LLC [Member] Batjer TopCo, LLC Entity Small Business Containers & Packaging Containers And Packaging Sector [Member] Containers And Packaging Sector UBM AcquireCo LLC UBM AcquireCo LLC [Member] UBM AcquireCo LLC Robbins Bros. Jewelry, Inc. Robbins Bros. Jewelry, Inc. [Member] Robbins Bros. Jewelry, Inc. MSC Income Fund Rule 10b5-1 Stock Repurchase Plan and Main Street Rule 10b5-1 Purchase Plan MSC Income Fund Rule 10b5-1 Stock Repurchase Plan And Main Street Rule 10b5-1 Purchase Plan [Member] MSC Income Fund Rule 10b5-1 Stock Repurchase Plan And Main Street Rule 10b5-1 Purchase Plan MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] PavCon LLC PavCon LLC [Member] PavCon LLC Document Type Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Taxable income earned prior to period end and carried forward for distribution next period Investment Company, Tax Basis, Taxable Income Earned Prior To Period End and Carried Forward For Distribution Next Period Investment Company, Tax Basis, Taxable Income Earned Prior To Period End and Carried Forward For Distribution Next Period NET ASSET VALUE PER SHARE (in dollars per share) NAV as of the beginning of the period (in dollars per share) NAV as of the end of the period (in dollars per share) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant Accounting Policies [Text Block] DTE Enterprises, LLC DTE Enterprises, LLC [Member] DTE Enterprises, LLC PIK Rate Investment, Interest Rate, Paid in Kind Subsequent Event [Line Items] Subsequent Event [Line Items] Statement of Stockholders' Equity [Abstract] Proceeds from May 2029 Notes Proceeds from Issuance of Long-Term Debt Local Phone Number Canada CANADA Core Transformers Core Transformers [Member] Core Transformers Compass Systems & Sales, LLC Colonial Electric Company LLC [Member] Colonial Electric Company LLC Debt instrument, basis spread on variable rate, floor (as a percent) Debt Instrument, Basis Spread On Variable Rate, Floor Debt Instrument, Basis Spread On Variable Rate, Floor Net unrealized appreciation (in dollars per share) Investment Company, Unrealized Gain (Loss) on Investment, Per Share Connect Telecommunications Solutions Holdings, Inc. Connect Telecommunications Solutions Holdings, Inc. [Member] Connect Telecommunications Solutions Holdings, Inc. Advisory agreement, average total assets threshold (as a percent) Advisory Agreement, Average Total Assets Threshold, Percent Advisory Agreement, Average Total Assets Threshold, Percent Commitments and contingencies (Note H) Commitments and Contingencies Electro Technical Industries, LLC Electro Technical Industries, LLC [Member] Electro Technical Industries, LLC Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Leisure Equipment & Products Leisure Equipment And Products Sector [Member] Leisure Equipment And Products Sector Executive Category: Executive Category [Axis] Inspire Aesthetics Management, LLC Inspire Aesthetics Management, LLC [Member] Inspire Aesthetics Management, LLC Cody Pools, Inc. Clad-Rex Steel, LLC [Member] Clad-Rex Steel, LLC Payment-in-kind interest Payment-in-Kind Interest Payment-in-Kind Interest Counterparty Name [Axis] Counterparty Name [Axis] Other Commitments [Table] Other Commitments [Table] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Supplemental cash flow disclosures: Supplemental Cash Flow Information [Abstract] PEO Name PEO Name UPS Intermediate, LLC UPS Intermediate, LLC [Member] UPS Intermediate, LLC Taxes paid Income Tax Paid, before Refund Received Total distributions accrued or paid to common stockholders Investment Company, Tax Basis, Distributions Accrued Or Paid To Common Stockholders Investment Company, Tax Basis, Distributions Accrued Or Paid To Common Stockholders Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Career Team Holdings, LLC Career Team Holdings, LLC [Member] Career Team Holdings, LLC Entity Tax Identification Number Prepaids and other assets Prepaid Expense and Other Assets Other Commitments [Line Items] Other Commitments [Line Items] Base management and incentive fees payable Management Fee Payable Brightwood Capital Fund Investments Brightwood Capital Fund Investments [Member] Brightwood Capital Fund Investments Entity Incorporation, State or Country Code Base Rate Base Rate [Member] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Incentive fee rate (as a percent) Management and Service Fees, Incentive Rate Proceeds from sales and repayments of debt investments in portfolio companies Proceeds From Sales And Repayments Of Debt Investments In Portfolio Companies Proceeds From Sales And Repayments Of Debt Investments In Portfolio Companies Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] ORGANIZATION AND BASIS OF PRESENTATION Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Debt Instrument [Axis] Subsequent Event [Table] Subsequent Event [Table] Distributors Distributors Sector [Member] Distributors Sector Total current tax expense (benefit) Investment Income, Operating, Tax Expense (Benefit), Current Investment Income, Operating, Tax Expense (Benefit), Current Measurement Input Type [Axis] Measurement Input Type [Axis] Annual Basis Point Rate Adviser Agreement, Annual Basis Point Reimbursement, Percent Adviser Agreement, Annual Basis Point Reimbursement, Percent O 2025 A2 Supplemental Dividends O 2025 A2 Supplemental Dividends [Member] O 2025 A2 Supplemental Dividends Insider Trading Arrangements [Line Items] Payment of deferred financing costs Payments of Financing Costs Berry Aviation, Inc. Berry Aviation, Inc. [Member] Berry Aviation, Inc. Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Committed capital Investment Company, Financial Support to Investee Contractually Required, Not Provided, Amount Xenon Arc, Inc. Xenon Arc, Inc. [Member] Xenon Arc, Inc. Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Diluted equity ownership percentage (as a percent) Investment Company, Average Fully Diluted Equity Ownership, Percentage Investment Company, Average Fully Diluted Equity Ownership, Percentage Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] DMA Industries, LLC Direct Marketing Solutions, Inc. [Member] Direct Marketing Solutions, Inc. Concentration risk, percentage (as a percent) Concentration Risk, Percentage Equity Awards Adjustments Equity Awards Adjustments [Member] Schedule of Summarized Dividend Reinvestment Plan Information Schedule of Summarized Dividend Reinvestment Plan Information [Table Text Block] Schedule of Summarized Dividend Reinvestment Plan Information Trading Companies & Distributors Trading Companies And Distributors Sector [Member] Trading Companies And Distributors Sector Industry Sector [Domain] Industry Sector [Domain] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Investment owned, percent of net assets (as a percent) Investment Owned, Net Assets, Percentage Book income and tax income differences, including debt origination, structuring fees, dividends, realized gains and changes in estimates Investment Company, Tax Basis, Book Income and Tax Income Differences, Increase (Decrease) In Taxable Income Investment Company, Tax Basis, Book Income and Tax Income Differences, Increase (Decrease) In Taxable Income Investment Company, Ratio To Average Net Assets Excluding Expense Waivers Investment Company, Ratio To Average Net Assets Excluding Expense Waivers [Abstract] Investment Company, Ratio To Average Net Assets Excluding Expense Waivers Corporate Facility Corporate Facility [Member] Corporate Facility General and administrative General and Administrative Expense Professional Services Professional Services Sector [Member] Professional Services Sector Distributions paid or accrued (in dollars per share) Investment Company, Distribution to Shareholders, Per Share Mini Melts of America, LLC Mini Melts of America, LLC [Member] Mini Melts of America, LLC Pinnacle TopCo, LLC Pinnacle TopCo, LLC [Member] Pinnacle TopCo, LLC Share Repurchase Program [Axis] Share Repurchase Program [Axis] Cumulative dividends Cumulative Dividends, Non-cash Cumulative Dividends, Non-cash Statement of Cash Flows [Abstract] Midwest US Midwest Region [Member] ZRG Partners, LLC ZRG Partners, LLC [Member] ZRG Partners, LLC Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Portfolio Investment Classification and Valuation of the Investment Portfolio Investment, Policy [Policy Text Block] Electrical Equipment Electrical Equipment Sector [Member] Electrical Equipment Sector IT Services IT Services Sector [Member] IT Services Sector RA Outdoors LLC RA Outdoors LLC [Member] RA Outdoors LLC Greater than $1.25 billion Annual Interest Rate Greater Than Billion [Member] Annual Interest Rate Greater Than Billion Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Entity Filer Category Dividends [Axis] Dividends [Axis] Effective interest rate (as a percent) Debt Instrument, average interest rate (as a percent) Debt Instrument, Interest Rate During Period Creative Foam Corporation Creative Foam Corporation [Member] Creative Foam Corporation Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Ratio of operating expenses excluding interest expense, to average NAV (as a percent) Investment Company, Operating Expenses Ratio Excluding Interest Expense Investment Company, Operating Expenses Ratio Excluding Interest Expense Number of portfolio investments in entities Investment Company, Number Of Portfolio Investments, Entities Investment Company, Number Of Portfolio Investments, Entities Percentage of loans with variable rate floors (as a percent) Investment Company, Percentage Of Loans With Variable Rate Floors Investment Company, Percentage Of Loans With Variable Rate Floors Net Change in Unrealized Appreciation (Depreciation) Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Entity Address, Address Line Two Stock, Class of Stock [Table] Stock, Class of Stock [Table] Total investment income Gross Investment Income, Operating Entity Address, Address Line One Investments in and Advances to Affiliates, at Fair Value [Roll Forward] Investments in and Advances to Affiliates, at Fair Value [Roll Forward] Principles of Consolidation Consolidation, Policy [Policy Text Block] Portfolio turnover ratio (as a percent) Investment Company, Portfolio Turnover Accretion of unearned income Accretion of Unearned Income Accretion of Unearned Income Number of lenders Debt Instrument, Number Of Lenders Debt Instrument, Number Of Lenders Discounted cash flow Valuation Technique, Discounted Cash Flow [Member] Statement [Table] Statement [Table] Proceeds from public offering of common stock, net of underwriting and offering costs Proceeds from Issuance Initial Public Offering OnPoint Industrial Services, LLC OnPoint Industrial Services, LLC [Member] OnPoint Industrial Services, LLC Investments in portfolio companies Payments To Investments In Portfolio Companies Payments To Investments In Portfolio Companies Behavior Development Group Holdings Behavior Development Group Holdings [Member] Behavior Development Group Holdings Interest income Investment Income, Interest Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] NET UNREALIZED APPRECIATION (DEPRECIATION): Investment Owned, Recognized Unrealized Appreciation (Depreciation), Net [Abstract] Investment Owned, Recognized Unrealized Appreciation (Depreciation), Net