Accretive (dilutive) effect of share issuances and repurchases Accretive Dilutive Effect Of Share Issuances And Repurchases Accretive (dilutive) effect of share issuances and repurchases. Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Component Manufacturing Component Manufacturing [Member] Component manufacturing. Remaining unused portion of Credit Facility commitment percentage Line of Credit Facility, Remaining Unused Capacity, Commitment Fee Percentage Line of credit facility, remaining unused capacity, commitment fee percentage. Net unrealized appreciation (depreciation) on investments Net Unrealized Appreciation (Depreciation) On Investments Net unrealized appreciation (depreciation) on investments. Income incentive fee payable - due to affiliate Income Incentive Fees Payable Due To Affiliate Income incentive fees payable due to affiliate. Allredi, LLC (fka Marco Group International OpCo, LLC) Allredi, Llc [Member] Allredi, Llc. Money Market Funds [Member] Money Market Funds Dividends to stockholders Amount Per Share Dividends Payable, Amount Per Share Accrued interest and fees payable Increase Decrease In Accrued Interest and Fees Payable Increase decrease in accrued interest and fees payable. Zonkd, LLC - Delayed Draw Term Loan Zonkd, LLC - Delayed Draw Term Loan [Member] Zonkd, LLC - delayed draw term loan. Geographical [Axis] Debt instrument interest rate percentage based on prior to certain conditions satisfied. Debt Instrument Interest Rate Percentage Based on Prior To Certain Conditions Satisfied Interest rate prior to certain conditions satisfied Net unrealized appreciation (depreciation) on investments Net unrealized appreciation (depreciation) on investments Unrealized Gain (Loss) on Investments Unrealized Gain (Loss) on Investments, Total Consumer Products Sector Consumer Products Sector [member] Consumer Products Sector. Aggregate fair value of total portfolio Debt Securities, Available-for-Sale Debt Securities, Available-for-sale, Total Investments at cost Cost Investment Owned, Cost Level 1 Fair Value, Inputs, Level 1 [Member] Percentage of amount of pre-incentive fee net investment income Percentage of Amount of Pre-incentive Fee Net Investment Income Percentage of amount of pre-incentive fee net investment income. Healthcare Services Healthcare Services [Member] Healthcare services. 3.267% Fixed Interest Rate Three Point Two Six Seven Percent Interest Rate [Member] Three point two six seven percent interest rate. Fiber Materials, Inc. Fiber Materials Inc [Member] Fiber Materials, Inc. Weighted Average Weighted Average [Member] Applied Data Corporation Applied Data Corporation [Member] Applied data corporation. Discounted Cash Flow Valuation Technique, Discounted Cash Flow [Member] Fair Value Measurements Fair Value Disclosures [Text Block] Ameriwater LLC AmeriWater LLC [Member] AmeriWater LLC. Summary of outstanding commitments Summary Of Outstanding Commitments [Table Text Block] Summary of outstanding commitments. Income Taxes Income Tax, Policy [Policy Text Block] Net realized gains (losses) on investments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Increase (decrease) in receivables from investments sold. Increase (Decrease) In Receivables From Investments Sold Receivables from investments sold Proceeds received from SBA debentures Proceeds Received from Small Business Administration Debentures Proceeds received from small business administration debentures. Additional interest rate on investments Additional Interest Rate On Investments Additional interest rate on investments. Number of residual investment porfolio companies Number of Residual Investment Porfolio Companies Number of residual investment porfolio companies. Investment represented more than ten percentage of aggregate investment portfolio Investment represented More Than Ten Percentage of Aggregate Investment Portfolio Investment represented more than ten percentage of aggregate investment portfolio. Accretion of loan origination fees Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset, Accretion Of Loan Origination Fees Fair value measurement with unobservable inputs reconciliation recurring basis asset, accretion of loan origination fees. Fair value, assets, transfers into level 3, amount Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Accrued administrative service expense payable Accrued Administrative Service Expense Payable Accrued administrative service expense payable January 2026 Notes 4.75% Notes due 2026 Four Point Seven Five Percent Notes Due Two Thousand Twenty Six [Member] Four Point Seven Five Percent Notes Due Two Thousand Twenty Six. Investment interest rate, PIK Investment, Interest Rate, Paid in Kind Subsequent Events Subsequent Events [Text Block] Pre-incentive fee net investment income Investment Company, Expense Ratio, after Fee Waiver and Incentive Fee Deduction Record Date Dividends Payable, Date of Record Dividend record date Borrowings under credit facility, net of deferred financing costs. Borrowings under Credit Facility, Net of Deferred Financing Costs Borrowings under Credit Facility, net of deferred financing costs (Note 6) Tedia Company, LLC - Revolving Loan Tedia Company, LLC - Revolving Loan [Member] Tedia Company, LLC - revolving loan. Five point nine eight eight percent interest rate. Five Point Nine Eight Eight Percent Interest Rate [Member] 5.988% Fixed Interest Rate SBA Debentures Small Business Administration Debentures [Member] Small Business Administration debentures. Number of shares repurchased under repurchase program Stock Repurchased During Period, Shares Safety Products Group, LLC - Common Equity (Units) Safety Products Group, LLC - Common Equity (Units) [Member] Safety Products Group, LLC - Common Equity (Units). Schedule of Stock by Class [Table] Investments, Fair Value Disclosure, Total Investments, Fair Value Disclosure Total Fair Value Measurement [Domain] Auto Crm Llc Auto CRM LLC [Member] Auto CRM LLC. Class of Stock [Line Items] Repayments of SBA debentures Repayments of Small Business Administration Debentures Repayments of small business administration debentures. Related Party Transactions [Abstract] Less: accumulated amortization Less: accumulated amortization Accumulated Amortization, Debt Issuance Costs R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - Senior Subordinated Debt R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - Senior Subordinated Debt [Member] R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - Senior Subordinated Debt. Total liabilities and net assets Liabilities and Equity Other Net Asset Value Per Share, Other Net asset value per share, other. Maximum amount of shares, sold Public offering of common stock, net of expenses Stock Issued During Period, Value, New Issues Dividend one. Dividend One [Member] Dividend One Net increase in net assets resulting from operations per share - basic and diluted Net Increase Decrease In Net Assets Resulting From Operations To Common Stockholders Basic And Diluted Net increase decrease in net assets resulting from operations to common stockholders basic and diluted. Percentage of equity investments held in portfolio companies Percentage of Equity Investments Held in Portfolio Companies Percentage of equity investments held in portfolio companies. R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - Common Equity R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - Common Equity [Member] R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - Common Equity. Payment of deferred financing costs Payment of Financing and Stock Issuance Costs Payment of Financing and Stock Issuance Costs, Total Cumulative number of shares Common Stock, shares issued Common Stock, Shares, Issued Common Stock, Shares, Issued, Total 2025 Long-Term Debt, Maturity, Year Two US GreenFiber, LLC US GreenFiber LLC [Member] US GreenFiber LLC. Dividends [Axis] Haematologic Technologies Inc Haematologic Technologies, Inc [Member] Haematologic Technologies, Inc. EBL, LLC (EbLens) EBL, LLC [Member] EBL, LLC. Percentage of Cost PercentageOfCost Percentage of cost. Schedule of Long-Term Debt Instruments [Table] Shares outstanding at end of period Beginning balance (in Shares) Ending balance (in Shares) Shares, Outstanding Summary of Deferred Financing Costs Amortized into Interest and Financing Expenses Summary Of Deferred Financing Costs Amortized Into Interest And Financing Expenses [Table Text Block] Summary of deferred financing costs amortized into interest and financing expenses. Equity Investments, Equity Fair Value Equity Securities, FV-NI Equity Securities, FV-NI, Total Percentage of non-qualifying assets fair value Percentage Of Non-qualifying Assets Fair Value Percentage of non-qualifying assets fair value. Related Party Transaction [Line Items] Tedia Company, LLC - Delayed Draw Term Loan Tedia Company, LLC - Delayed Draw Term Loan [Member] Tedia Company, LLC - delayed draw term loan. 2023 Long-Term Debt, Maturity, Remainder of Fiscal Year Income tax examination, description Income Tax Examination, Description Summary of Investment Holdings [Line Items] Debt Debt Disclosure [Text Block] First Lien Debt and Preferred Equity First Lien Debt and Preferred Equity [Member] First lien debt and preferred equity. 2.793% Fixed Interest Rate Two Point Seven Nine Three Percent Interest Rate [Member] Two point seven nine three percent interest rate. Percentage of voting securities Percentage Of Voting Securities Percentage of voting securities. Subsequent Event [Member] Subsequent Events Subsequent Event Type [Axis] Fair value of loans included in investments Fair Value of Loans included in Investments Fair value of loans included in investments. EBITDA Multiples Measurement Input, EBITDA Multiple [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Applegate Greenfiber Intermediate Inc. (fka US GreenFiber, LLC) Applegate Greenfiber Intermediate Inc [Member] Applegate greenfiber intermediate Inc. OnePath Systems, LLC OnePath Systems, LLC [Member] OnePath Systems, LLC. Partial Loan and Equity Sales Partial Loan And Equity Sales Policy Text Block Partial loan and equity sales policy text block. Net change in unrealized appreciation (depreciation) on investments Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) DealerBuilt acquisition, LLC. DealerBuilt Acquisition, LLC [Member] DealerBuilt Acquisition, LLC Investment, Issuer Affiliation [Axis] Percentage of board representation Percentage Of Board Representation Percentage of board representation. Investments in and Advances to Affiliates [Line Items] Statement of Stockholders' Equity [Abstract] Lender Name [Axis] Summary of Significant Unobservable Inputs by Valuation Technique to Determine Fair Value Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Maturity Date Maturity date Debt Instrument, Maturity Date 5.861% Fixed Interest Rate Five Point Eight Six One Percent Interest Rate [Member] Five point eight six one percent interest rate Investments and money market funds owned at cost. Investments and Money Market Funds Owned at Cost Cost Long-Term Debt Total Accrued capital gains incentive fee payable Accrued Capital Gains Incentive Fee Payable Accrued capital gains incentive fee payable Fair Value Measurement Inputs and Valuation Techniques [Line Items] Base management fee payable, net of base management fee waiver - due to affiliate Base management fee payable Management Fee Payable Interest Income Investment Income, Interest Dividends Payable, Date Declared Dividend declared date Choice Technology Solutions, LLC (dba Choice Merchant Solutions, LLC) - Revolving Loan. Choice Technology Solutions, LLC (dba Choice Merchant Solutions, LLC) - Revolving Loan [Member] Choice Technology Solutions, LLC (dba Choice Merchant Solutions, LLC) - Revolving Loan Level Education Group LLC Level Education Group, LLC [Member] Level education group, LLC. Scenario [Domain] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Prepaid expenses and other assets Increase (Decrease) in Prepaid Expenses, Other Supplemental Dividend Supplemental dividend. Net Change in Unrealized Appreciation (Depreciation) Investment Owned, Unrecognized Unrealized Appreciation (Depreciation), Net Investment Owned, Unrecognized Unrealized Appreciation (Depreciation), Net, Total Plan Name [Domain] Common stock issued under At the market program Common Stock Issued Under At the Market Program Common stock issued under At the market program. Canada CANADA First Lien Debt One First Lien Debt One [Member] First lien debt one. Credit Facility Borrowings Senior Secured Revolving Credit Facility [Member] Senior secured revolving credit facility. Cumulative underwriting fees and commission and offering costs Cumulative Underwriting Fees and Commission and Offering Costs Cumulative underwriting fees and commission and offering costs. Pinnergy, Ltd. Pinnergy Ltd [Member] Pinnergy, Ltd. Stockholders' Equity, Period Increase (Decrease), Total Stockholders' Equity, Period Increase (Decrease) Net increase (decrease) in net assets resulting from operations Fidus Equity Fund I, L.P. Fidus Equity Fund I, Limited Partnership [Member] Fidus Equity Fund I, L.P. Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accrued interest and fees payable Accrued Interest And Fees Payable Accrued interest and fees payable. Financial Instruments [Domain] Ending Balance Beginning Balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Line of Credit Facility [Table] Investment, Name [Axis] Debt instrument term Debt Instrument, Term Change in Accounting Estimate [Line Items] Interest and dividend income paid-in-kind Interest and dividend income paid-in-kind. Investment Owned, Balance, Principal Amount Principal Amount - Debt Investments Plan Name [Axis] Total Distribution Total distribution. Geographical [Domain] Total assets Assets Incentive fee Payment for Incentive Fee Net investment income before income taxes Net investment income Investment Income, Net Line of Credit Facility [Line Items] Tedia Company LLC Tedia Company, LLC [Member] Tedia Company, LLC. Number of Investment Porfolio Companies Number of investment porfolio companies. Number of investment portfolio companies Control Investments Investment, Affiliated Issuer, Controlled [Member] Offering expenses Less: unamortized deferred financing costs Less: unamortized deferred financing costs Unamortized deferred financing costs Debt Issuance Costs, Net Retail Retail Sectors [Member] Retail sectors. Related Party, Type [Domain] Total distributable earnings Retained Earnings (Accumulated Deficit) Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit), Beginning Balance Retained Earnings (Accumulated Deficit), Total Proceeds from loan origination fees Proceeds from Fees Received Supplemental Cash Flow Information [Abstract] Supplemental information and non-cash activities: Netbase Solutions Inc Netbase Solutions, Inc. [Member] Netbase solutions, Inc. Investments in and Advances to Affiliates [Table] Minimum Minimum [Member] Suited Connector LLC Suited Connector LLC [Member] Suited Connector LLC. Realized Gains or Losses and Unrealized Appreciation or Depreciation on Investments Realized Gains Or Losses And Unrealized Appreciation Or Depreciation On Investments Policy Text Block Realized gains or losses and unrealized appreciation or depreciation on investments policy text block. Percentage of capital gains incentive fee accrued Percentage of Capital Gains Incentive Fee Accrued Percentage of capital gains incentive fee accrued Significant Accounting Policies Significant Accounting Policies [Text Block] Percentage of public offering price. Percentage of public offering price Percentage of Public Offering Price Forecast Forecast [Member] Affiliate Investments Affiliate Investments [Member] Affiliate investments. Fair Value Measurement Inputs and Valuation Techniques [Table] Equity Component [Domain] Cash Distribution Cash distribution. Accounts payable and other liabilities Accounts Payable and Other Accrued Liabilities Wonderware Holdings, LLC dba CORE Business Technologies Wonderware Holdings, LLC dba CORE Business Technologies [Member] Wonderware Holdings, LLC (dba CORE Business Technologies). January 2026 Notes. January 2026 Notes [Member] January 2026 Notes Investment Company, Financial Highlights [Line Items] Aerospace And Defense Manufacturing Aerospace and Defense Manufacturing [Member] Aerospace and defense manufacturing. Payments of dividends including expenses. Payments Of Dividends Including Expenses Dividends paid to stockholders, including expenses Dividends paid to stockholders, including expenses 3.190% Fixed Interest Rate Three Point One Nine Zero Percent Interest Rate [Member] Three point one nine zero percent interest rate. Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Adjustments to reconcile net increase (decrease) in net assets resulting from operations to net cash provided by (used for) operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Variable Index Spread Investment, Basis Spread, Variable Rate Total Amount Paid Stock Issued During Period, Value, Treasury Stock Reissued Measurement Frequency [Axis] Debt Disclosure [Abstract] Common Stock, shares authorized Common Stock, Shares Authorized Rhino Assembly Company, LLC - Delayed Draw Commitment Rhino Assembly Company, LLC - Delayed Draw Commitment [Member] Rhino Assembly Company, LLC - delayed draw commitment. Fair Value, by Balance Sheet Grouping [Table] 5.341% Fixed Interest Rate Five Point Three Four One Percent Interest Rate Two [Member] Five point three four one percent interest rate two. Interest and financing expenses Total interest and financing expenses Interest and Debt Expense Power Grid Components, Inc Power Grid Components, Inc. [Member] Power Grid Components, Inc. [Member] GP&C Operations, LLC GP&C Operation ,LLC [Member] GP&C operation ,LLC. Debt obligations fair value Debt obligations Long-Term Debt, Fair Value Capital gains incentive fee accrued (reversed). Capital Gains Incentive Fee Accrued (Reversed) Capital gains incentive Fee Accrued (Reversed) Maximum number of common stock purchasable under stock repurchase program Maximum common stock can be purchased under repurchase program Stock Repurchase Program, Authorized Amount Administrative service expenses Administrative Fees Expense ASSETS Assets [Abstract] Net proceeds from common stock under ATM program Net proceeds Proceeds from Issuance of Common Stock Aom Intermediate Holdco Llc AOM Intermediate Holdco, LLC [Member] AOM Intermediate Holdco, LLC. Two K Direct Inc Two K Direct Inc [Member] 2KDirect, Inc. Combined Systems, Inc Combined Systems Inc [Member] Combined Systems Inc. Hallmark Health Care Solutions Inc Hallmark Health Care Solutions, Inc [Member] Hallmark Health Care Solutions, Inc. Common stock, $0.001 par value (100,000,000 shares authorized, 28,453,469 and 24,727,788 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively) Common Stock, Value, Issued Common Stock, Value, Issued, Ending Balance Common Stock, Value, Issued, Beginning Balance Common Stock, Value, Issued, Total Administrative service expenses Administrative Service Expenses Administrative service expenses. Pre-incentive fee fixed hurdle rate Pre-incentive Fee Fixed Hurdle Rate Pre-incentive fee fixed hurdle rate. SBIC debenture program, maximum amount outstanding SBA debentures. SBIC Debenture Program, Maximum Amount Outstanding SBA Debentures SBIC debenture program, maximum amount outstanding SBA debentures 5.341% Fixed Interest Rate Five Point Three Four One Percent Interest Rate Three [Member] Five point three four one percent interest rate three. Medsurant Holdings, LLC Medsurant Holdings LLC [Member] Medsurant holdings, LLC Aeronix Inc Aeronix Inc [Member] Aeronix Inc. Amortization of deferred equity financing costs Amortization Of Deferred Equity Financing Costs Amortization of deferred equity financing costs. Income tax provision (benefit) Income Tax Expense (Benefit) Income Tax Expense (Benefit), Total Total deferred financing costs Debt Issuance Costs, Gross Schedule of Portfolio Composition by Type And by Geographic Region at Fair Value Investment [Table Text Block] Maximum aggregate offering price of common stock under at-the-market program Maximum Aggregate Offering Price of Common Stock Under At The Market Program Maximum aggregate offering price of common stock under at-the-market program. 2027 Long-Term Debt, Maturity, Year Four Percentage of net capital gains Percentage of Net Capital Gains Percentage of net capital gains. Taxes paid on deemed distributions Investment Company, Tax Return of Capital Distribution, Per Share R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - First Lien Debt R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - First Lien Debt [Member] R1 Holdings, LLC (dba RoadOne IntermodaLogistics) - First Lien Debt. Delayed Draw Commitment Four Delayed Draw Commitment Four [Member] Delayed draw commitment four. Expenses other than incentive fee Investment Company, Expense Ratio, after Fee Waiver and before Incentive Fee Deduction Measurement Input Type [Domain] BP Thrift Buyer, LLC BP Thrift Buyer, LLC [Member] BP Thrift Buyer, LLC. Warrants Notes Warrants Notes [Member] Warrants notes. Wonderware Holdings, LLC (dba CORE Business Technologies) - Delayed Draw Term Loan Wonderware Holdings, LLC (dba CORE Business Technologies) - Delayed Draw Term Loan [Member] Wonderware Holdings, LLC (dba CORE Business Technologies) - delayed draw term loan. Fee Income Fee Income Policy Text Block Fee income policy text block. Proceeds receivable from stock offering. Proceeds Receivable From Stock Offering Proceeds receivable from stock offering Cumulative gross proceeds from issuance of common stock Cumulative Gross Proceeds from Issuance of Common Stock Cumulative gross proceeds from issuance of common stock. Valuation Approach and Technique [Domain] Average debt per share Average Debt Per Share Average debt per share. Schedule of Consolidated Schedule of Investments in and Advances to Affiliates Investments in and Advances to Affiliates [Table Text Block] Cash Distribution Dividends, Cash Dividends, Cash, Total United States West United States West [Member] United States West. Aggregate principal amount Total outstanding SBA debentures Debt Instrument, Face Amount Earnings and Net Asset Value per Share Earnings Per Share, Policy [Policy Text Block] Total net change in unrealized appreciation (depreciation) on investments Total net change in unrealized appreciation (depreciation) on investments Net change in unrealized (appreciation) depreciation on investments Net Change In Unrealized (appreciation) Depreciation on Investments Net change in unrealized (appreciation) depreciation on investments. Healthcare Products Healthcare Products [Member] Healthcare products. Weighted-average price Average Offering Price Weighted Average Price of Common Stock Under At The Market Program Weighted average price of common stock under at the market program. Measurement Basis [Axis] Delayed Draw Commitment Two Delayed Draw Commitment Two [Member] Delayed Draw Commitment Two. 6.083% Fixed Interest Rate Six Point Zero Eight Three Percent Interest Rate [Member] Six point zero eight three percent interest rate. Net realized gain (loss) on investments, net of tax (provision) Investment Company, Gain (Loss) on Investment, Per Share SBA debentures, net of deferred financing costs (Note 6) Debentures Debentures. Expenses: Operating Expenses [Abstract] Diversified Search LLC Member Diversified Search LLC [Member] Diversified Search LLC. Long-Term Debt, Type [Domain] Interest earning on unfunded balance commitment Interest Earning On Unfunded Balance Commitment Interest earning on unfunded balance commitment. Subsequent Events [Abstract] Secured borrowings. Secured Borrowings [Member] Secured Borrowings Dividends and Distributions [Abstract] Dividends and distributions. Commitments and Contingencies Disclosure [Abstract] United States Southwest United States Southwest [Member] United States Southwest. Control Investments Control Investments [Member] Control investments. Percentage of investment company taxable income Percentage Of Investment Company Taxable Income Percentage of investment company taxable income. Common Stock Equity [Text Block] Proceeds from sales and repayments including principal return of capital distributions and realized gains. Proceeds From Sales And Repayments Including Principal Return Of Capital Distributions And Realized Gains Proceeds from sales and repayments Income tax (provision) benefit from realized gains on investments Income tax provision (benefit) from realized gains on investments. Income tax (provision) benefit from realized gains on investments Income Tax Provision Benefit From Realized Gains on Investments 3.260% Fixed Interest Rate Three Point Two Six Zero Percent Interest Rate [Member] Three point two six zero percent interest rate. Cash payments for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Garlock Printing And Converting Operations LLC Garlock Printing And Converting Operations LLC [Member] Garlock printing and converting operations LLC. Accounts payable and other liabilities Increase (Decrease) in Accounts Payable and Other Operating Liabilities DRIP DRIP Dividend reinvestment plan. Additional paid-in capital Additional Paid in Capital Additional Paid in Capital, Ending Balance Additional Paid in Capital, Beginning Balance Additional Paid in Capital, Total Investment, Issuer Affiliation [Domain] LIABILITIES Liabilities [Abstract] NET ASSETS Equity, Attributable to Parent [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Total investments, at fair value Investments, at fair value Fair Value Investments at Fair Value Fair Value, beginning balance Fair Value, ending balance Secured Borrowings Secured Debt [Member] Average debt outstanding Long-Term Debt, Average Amount Outstanding Non-accrual Non Accrual Policy Text Block Non accrual policy text block. Earnings Per Share [Abstract] Per common share data: Asset coverage ratio. Asset Coverage Ratio Asset coverage ratio Incentive fee Investment Company, Incentive Fee to Average Net Assets Loss Contingencies [Table] Gross investment income. Gross Investment Income [Abstract] Investment Income: Credit Facility upfront fees Upfront fees Deferred Upfront Fees Deferred upfront fees. Weighted average stated interest rate, period end Weighted average stated interest rate, period end Weighted average interest rate Debt, Weighted Average Interest Rate Investment, Name [Domain] Origination and Closing Fees Origination And closing Fee Origination and closing fee. Dividends declared Dividends declared Dividends, Common Stock Dividends, Common Stock, Total Accounting Policies [Abstract] UPG Company, LLC UPG Company, LLC [Member] UPG Company, LLC. Investment and money market funds owned percent of net assets. Investment and Money Market Funds Owned Percent of Net Assets Percent of Net Assets Taxes payable Taxes Payable Taxes Payable, Total Supplemental dividend two. Supplemental Dividend Two [Member] Supplemental Dividend Two Scenario [Axis] Investment maturity period Investment Maturity Period Investment maturity period. 5.439% Fixed Interest Rate Five Point Four Three Nine Percent Interest Rate Two [Member] Five point four three nine percent interest rate two. Capital gains incentive fee payable - due to affiliate Capital gains incentive fee payable Capital Gains Incentive Fee Payable Capital gains incentive fee payable. Revolving Credit Facility Revolving Credit Facility [Member] Dividends Payable Dividends payable Weighted Average Cost of Capital Measurement Input, Weighted Average Cost of Capital [Member] Measurement input, weighted average cost of capital. Earnings Per Share, Basic, Total Earnings Per Share, Basic Net investment income per share-basic 6.047% Fixed Interest Rate Six Point Zero Four Seven Percent Interest Rate [Member] Six point zero four seven percent interest rate. Interest and Dividend Income Interest And Dividend Income Policy Text Block Interest and dividend income policy text block. Commitments and contingencies (Note 7) Commitments and Contingencies Payment-in-kind Interest Income Investment Income Payment In Kind Interest income Investment income payment in kind interest income. Income Statement [Abstract] Investment Investments Investments, Total Average fully diluted equity ownership Percentage. Average Fully Diluted Equity Ownership Percentage Average fully diluted equity ownership percentage Related Party, Type [Axis] Affiliate Investment Affiliate Investment Member Affiliate investment member. Money market funds owned percent of net assets Money Market Funds Owned Percent of Net Assets Percentage of Net Assets Sale of participating interest principal amount Proceeds from Sale of Interest in Corporate Unit Measurement Input Type [Axis] Statistical Measurement [Domain] Loss Contingencies [Line Items] Net Cash Provided by (Used in) Operating Activities Net cash provided by (used for) operating activities Net proceeds from the notes Proceeds from Issuance of Debt Capital gains incentive fee payable - due to affiliate Capital Gains Incentive Fee Payable Due to Affiliate Capital gains incentive fee payable due to affiliate. Statistical Measurement [Axis] SBA debenture leverage fees Leverage fees Debenture Leverage Fees Debenture leverage fees. Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Stockholders' Equity Note [Abstract] Winona Foods Inc Winona Foods, Inc [Member] Winona Foods, Inc. Dividend Income Investment Income, Dividend Earnings Per Share, Diluted, Total Earnings Per Share, Diluted Net investment income per share-diluted Cumulative number of shares Subsidiary or Equity Method Investee, Cumulative Number of Shares Issued for All Transactions Proceeds from sales and repayments of investments Proceeds from sales and repayments of investments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Stock Repurchase Program Stock Repurchase Program Policy Text Block Stock repurchase program policy text block. Thereafter Long-Term Debt, Maturity, after Year Five Debt Instrument, Name [Domain] Fair Value Hierarchy and NAV [Domain] American AllWaste LLC (dba WasteWater Transport Services) - First Lien Debt American Allwaste Llc Dba Waste water Transport Services First Lien Debt [Member] American Allwaste Llc dba waste water transport services first lien debt. Tax year subject to examination Open Tax Year Nineteen And Ten Portfolio Company Investments [Member] Nineteen And Ten Portfolio Company Investments [Member] 19 and 10 Portfolio Company Investment EBL, LLC (EbLens) - Common Equity (Units) EBL, LLC (EbLens) - Common Equity (Units) [Member] EBL, LLC (EbLens) - Common Equity (Units). Fair Value, Recurring Fair Value, Recurring [Member] Senior asset coverage ratio. Senior Asset Coverage Ratio Senior asset coverage ratio Number of reportable segments Number of Reportable Segments Percentage of minimum qualifying assets to purchase non qualifying assets Percentage Of Minimum Qualifying Assets To Purchase Non Qualifying Assets Percentage of minimum qualifying assets to purchase non qualifying assets. Scheduled to Mature Debt Liabilities Schedule of Maturities of Long-Term Debt [Table Text Block] Equity Equity investment. Equity Investment Net assets at end of period Net Assets Net Assets, Ending Balance Net Assets, Beginning Balance Net Assets, Total First Lien Debt First Lien Debt [Member] First lien debt. Consolidation Consolidation, Policy [Policy Text Block] Schedule of Change in Accounting Estimate [Table] Income incentive fee payable - due to affiliate Increase Decrease in Income Incentive Fee Payable Due To Affiliate Increase decrease in income incentive fee payable due to affiliate. Supplemental dividend one. Supplemental Dividend One [Member] Supplemental Dividend One Base management fee Payment for Management Fee Accretion of original issue discount Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset, Accretion Of Original Issue Discount Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset, Accretion Of Original Issue Discount Total expenses Total expenses Investment Company Expense Ratio To Average Net Assets Investment company, expense ratio to average net assets. Credit Facility [Domain] Equity [Abstract] Proceeds from (Repayments of) Lines of Credit Proceeds received from (repayments of) borrowings under Credit Facility, net Winona Foods, Inc. - First Lien Debt Winona Foods, Inc. - First Lien Debt [Member] Winona Foods, Inc. - First lien debt. Notes Senior Notes [Member] Variable Index Floor Investment Variable Index Floor Rate Investment variable index floor rate. Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Schedule of Financial Highlights Investment Company, Financial Highlights [Table Text Block] Asset Coverage Measurement Input, Asset Coverage [Member] Measurement input, asset coverage. Additional interest rate on investments, PIK Additional Interest Rate On Investments Paid In Kind Additional interest rate on investments paid-in kind. Equity Components [Axis] Percentage of excise tax Percentage Of Excise Tax Percentage of excise tax. Investments, Debt and Equity Securities [Abstract] Secured borrowings. Secured Borrowings Secured borrowings Purchase of investments Payments for Purchase of Securities, Operating Activities Summary of Common Stock Summary of Common Stock [Table Text Block] Summary of common stock. Sale of Stock [Axis] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Statement of Cash Flows [Abstract] Summary of Interest and Fees Related to Debt Schedule Of Interest And Financing Expenses Related To Debt [Table Text Block] Schedule of interest and financing expenses related to debt. Percentage of Fair Value PercentageOfFairValue Percentage of fair value. Debt instrument interest rate percentage based on after certain conditions satisfied. Debt Instrument Interest Rate Percentage Based on After Certain Conditions Satisfied Interest rate after certain conditions satisfied Summary of Inputs Used to Value Debt Obligations Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Pooling Date Debt Instrument, Pooling Date Debt instrument, pooling date. Deferred Offering Costs Deferred Charges, Policy [Policy Text Block] Four point five three three percent interest rate. Four Point Five Three Three Percent Interest Rate [Member] 4.533% Fixed Interest Rate Netbase Solutions, Inc. (dba Netbase Quid) - First Lien Debt (last out) Netbase Solutions, Inc. (dba Netbase Quid) - First Lien Debt (last out) [Member] Netbase Solutions, Inc. (dba Netbase Quid) - First Lien Debt (last out). Common Stock, par value Common Stock, Par or Stated Value Per Share Specialty Distribution Specialty Distribution [Member] Specialty distribution. 5.861% Fixed Interest Rate Five Point Eight Six One Percent Interest Rate One [Member] Five point eight six one percent interest rate one. Debt instrument, maturity year range, end Debt Instrument, Maturity Year Range, End Debt instrument, maturity year range, end. Fixed Interest Rate Interest rate Debt Instrument, Interest Rate, Stated Percentage Maximum Maximum [Member] Virtex Enterprises, LP. Virtex Enterprises, LP [Member] Virtex Enterprises, LP Steward Holding LLC (dba Steward Advanced Materials) Steward Holding LLC [Member] Steward holding LLC. Total Distribution Dividends Dividends, Total 5.439% Fixed Interest Rate Five Point FourThree Nine Percent Interest Rate [Member] Five point four three nine percent interest rate. Organization and Nature of Business Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] 3.277 % Fixed Interest Rate Three Point Two Seven Seven Percent Interest Rate [Member] Three point two seven seven percent interest rate. Debt instrument, maturity year range, start Debt Instrument Maturity Year Range Start 1 Debt instrument maturity year range start 1. Schedule of Investments [Abstract] Payments of Dividends Payments of Dividends, Total Dividends payable to stockholders Dividends payable Level 3 Fair Value, Inputs, Level 3 [Member] Average Price Paid Per Share Shares Acquired, Average Cost Per Share Fair Value, Recurring and Nonrecurring [Table] Written notice period for termination of agreement Written notice period for termination of agreement. Net increase (decrease) in cash and cash equivalents Net increase (decrease) in cash and cash equivalents Performing first lien bank loans, minimum percentage Minimum utilization of commitment fee percentage Line of Credit Facility, Minimum Utilization Commitment Fee Percentage Line of credit facility, minimum utilization commitment fee percentage. Equity investments, Warrants range Derivative Asset, Measurement Input Deferred Financing Costs Deferred Financing Costs Policy Text Block Deferred financing costs policy text block. 3.249% Fixed Interest Rate Three Point Two Four Nine Percent Interest Rate [Member] Three point two four nine percent interest rate. Other general and administrative expenses Other General and Administrative Expense Investment Risks Investment Risk Policy Text Block Investment risk policy text block. Notes debt issue costs Debt issue costs Debt Issue Costs Debt issue costs. Total Debt Securities, Held-to-Maturity, Nonaccrual Summary of Carrying Value and Fair Value of Debt Obligations Fair Value, by Balance Sheet Grouping [Table Text Block] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Fidus Investment Advisors LLC Fidus Investment Advisors LLC [Member] Fidus Investment Advisors LLC . Spectra A&D Acquisition, Inc. Steward Holding LLC (dba Steward Advanced Materials) Spectra A&D Acquisition, Inc. (fka FDS Avionics Corp.) Spectra A&D Acquisition, Inc. White Label Communications, LLC White Label Communications, LLC [Member] White Label Communications, LLC. Purchase of investments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Proceeds received from repayments of secured borrowings, net. Proceeds Received From Repayments Of Secured Borrowings, Net Proceeds received from (repayments of) Secured Borrowings, net FAR Research Inc. FAR Research Inc [Member] FAR research Inc. Available under ATM program Share Value Available Under At The Market Program Share value available under at the market program. Investment Company, Financial Highlights [Abstract] Weighted Average Number of Shares Outstanding, Basic, Total Weighted Average Number of Shares Outstanding, Basic Weighted average number of shares outstanding - basic Second Lien Debt Second Lien Debt [Member] Second lien debt. Warrant or rights percentage of outstanding debt principal to purchase Warrant Or Rights Percentage Of Outstanding Debt Principal To Purchase Warrant or rights percentage of outstanding debt principal to purchase. 5.861% Fixed Interest Rate Five Point Eight Six One Percent Interest Rate Three [Member] Five point eight six one percent interest rate three Net investment income Investment Company, Investment Income (Loss), Per Share First Lien Debt Six First Lien Debt Six [Member] First lien debt six. Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Number of Shares Purchased and Reissued DRIP Shares Shares issued under dividend reinvestment plan, shares Total return based on market value Investment Company Total Return Based On Market Value Investment company, total return based on market value. Loss on extinguishment of debt Realized losses on extinguishment of debt Realized losses on extinguishment of debt Realized losses on extinguishment of debt Realized losses on extinguishment of debt Loss on extinguishment of debt Environmental Industries Environmental Industries [Member] Environmental industries. Distributions from capital gains Investment Company Distributions From Capital Gains Per Share Investment company, distributions from capital gains per share. Prime AE Group, Inc Prime AE Group, Inc. [Member] Prime AE Group, Inc. Statement [Table] Schedule of Related Party Transactions, by Related Party [Table] Investments as percentage of total assets Investments As Percentage Of Assets Investments as percentage of assets. Investment Classification Investment, Policy [Policy Text Block] Related Party Transactions Related Party Transactions Disclosure [Text Block] Unitranche Investments [Member] Unitranche investments. Statement [Line Items] Aldinger company. Aldinger Company [Member] Aldinger Company Mirage Trailers LLC Mirage Trailers LLC [Member] Mirage trailers LLC. Valuation technique, enterprise value. Enterprise Value Valuation Technique, Enterprise Value [Member] Debt obligations fair value Debt Investments, Fair Value Debt Instrument, Fair Value Disclosure, Total Debt investments United States Midwest United States Midwest [Member] United States Midwest. Unfunded Commitment Commitments outstanding to fund various undrawn revolving loans, other debt investments and capital commitments. Commitments Outstanding to Fund Various undrawn revolving loans, other debt investments and capital commitments Commitments outstanding to fund various undrawn revolving loans, other debt investments and capital commitments. Subsequent Event [Line Items] Warrants Warrant Warrant [Member] Income incentive fee Income Incentive Fee Income incentive fee Ownership percentage of outstanding voting securities in portfolio investment Ownership Percentage of Outstanding Voting Securities in Portfolio Investment Ownership percentage of outstanding voting securities in portfolio investment. Hilco Plastics Holdings, LLC (dba Hilco Technologies) Hilco Plastics Holdings LLC [Member] Hilco plastics holdings, LLC. Schedule of Investments Type With Corresponding Percentage of Total Portfolio Investments Investment Holdings, Schedule of Investments [Table Text Block] Equity Investments, Equity, Range Equity Securities, FV-NI, Measurement Input Common Stock Common Stock [Member] Common Stock [Member] Debt Instrument [Line Items] Percentage of portfolio investments at fair value Percentage of Portfolio Investments at Fair Value Percentage of portfolio investments at fair value. Capital gains incentive fee (reversal) - due to (from) affiliate Increase Decrease In Capital Gains Incentive Fee Reversal Due To From Affiliate Increase decrease in capital gains incentive fee reversal due to from affiliate. Portfolio Company Investments Investment [Text Block] Total Amount Paid DRIP Shares Value Shares issued under dividend reinvestment plan Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents, at Carrying Value, Ending Balance Cash and Cash Equivalents, at Carrying Value, Beginning Balance Cash and Cash Equivalents, at Carrying Value, Total Investment, Interest Rate, Paid in Cash Repurchase of common stock Stock Repurchased During Period, Value Total net realized gain (loss) on investments Total net realized gain (loss) on investments Net realized gain (loss) on investments, net of taxes Net realized (gain) loss on investments Realized gain (loss) on investment Administration fee payable and other - due to affiliate Administration Fees Payable and Other Due To Affiliate Administration fees payable and other due to affiliate. 3.209% Fixed Interest Rate Three Point Two Zero Nine Percent Interest Rate [Member] Three point two zero nine percent interest rate. Average net assets Average Net Assets Average net assets. Percentage of net capital gains realized Percentage Of Net Capital Gains Realized Percentage of net capital gains realized. Unused commitments amount Debt Instrument, Unused Borrowing Capacity, Amount Total return based on net asset value Investment Company, Total Return Investment Advisory Agreement Investment Advisory Agreement [Member] Investment advisory agreement. Westerns Smokehouse, LLC [Member] Westerns Smokehouse LLC Western's Smokehouse, LLC. Summary of Issued and Outstanding SBA Debentures Schedule of Debt [Table Text Block] Professional fees Professional Fees Investment in number of shares or units Investment Owned, Balance, Shares Net realized gain (loss) on investments, net of taxes. Net Realized Gain (Loss) on Investments, Net of Taxes Net realized gain (loss) on investments, net of taxes Cardboard Box Llc Dba Anthonys Coal Fired Pizza Cardboard Box LLC dba Anthony's Coal Fired Pizza [Member] Cardboard Box LLC dba Anthony's Coal Fired Pizza. Dividends [Domain] Fair value, assets, transfers out of level 3, amount Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Maturity Investment Maturity Date Cash payments for taxes, net of tax refunds received Income Taxes Paid, Net Income Taxes Paid, Net, Total Total expenses, net of base management fee waiver Expenses Net of Base Management Fee Waiver Expenses net of base management fee waiver. Money market funds at fair value Money Market Funds At Fair Value Fair Value Sale of Stock [Domain] Pfanstiehl, Inc Pfanstiehl Inc [Member] Pfanstiehl, Inc. Portfolio turnover ratio Investment Company Portfolio Turnover Ratio Investment company, portfolio turnover ratio. Taxes payable Increase (Decrease) in Income Taxes Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Including Option Exercised Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Including Option Exercised, Total Proceeds from common stock offerings, net of expenses Proceeds from loan origination fees Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset, Proceeds From Loan Origination Fees Fair value measurement with unobservable inputs reconciliation recurring basis asset, proceeds from loan origination fees. 1.398% Fixed Interest Rate One Point Three Nine Eight Percent Interest Rate [Member] One point three nine eight percent interest rate. Dividend two. Dividend Two [Member] Dividend Two Recent Accounting Pronouncement New Accounting Pronouncements, Policy [Policy Text Block] Gross Investment Income, Operating Total investment income At-the-Market Offering Program At-the-Market Offering Program [Member] At-the-market offering program. Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Schedule of Fair Value Measurements of Investments by Major Class According to Fair Value Hierarchy Notes, net of deferred financing costs (Note 6) Notes Payable Notes Payable, Total Industry Sector [Axis] Financial Instrument [Axis] Information Technology Services Information Technology Services [Member] Information Technology Services [Member] Prepayment of debentures Prepayment of Debentures Prepayment of debentures. November 2026 Notes. November 2026 Notes [Member] November 2026 Notes Accretion of loan origination fees Accretion of Loan Origination Fees Accretion of loan origination fees. Net realized and unrealized gains (losses) on investments: Gain (Loss), Investment and Derivative, Operating, and Foreign Currency Transaction, before Tax [Abstract] Netbase Solutions, Inc. (dba Netbase Quid) - First Lien Debt (last out) Netbase Solutions, Inc. (dba Netbase Quid) - First Lien Debt (last out) One [Member] Netbase Solutions, Inc. (dba Netbase Quid) - First Lien Debt (last out) One [Member] Increase (decrease) in payables for investments purchased. Increase (Decrease) In Payables For Investments Purchased Payables for investments purchased Unfunded commitment Investment Company, Financial Support to Investee Contractually Required, Not Provided, Amount Investment commitment amount Aggregate amount of capital gains incentive fees Aggregate amount of capital gains incentive fees Aggregate amount of capital gains incentive fees. Affiliate Investments Investment, Affiliated Issuer [Member] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Weighted average offering Price Weighted Average Offering Price of Common Stock Weighted average offering price of common stock. Transportation Services Transportation Services [Member] Transportation services. Summary of Reconciliation of Beginning and Ending Balances for Fair Valued Investments Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Variable Rate [Domain] Bedford Precision Parts L L C Bedford Precision Parts L L C [Member] Bedford precision parts LLC. Variable Index Floor Investment, Interest Rate, Floor Entity File Number Credit facility maturity date Line of Credit Facility, Expiration Date Proceeds from sales and repayments Proceeds from (Repayments of) Debt Proceeds from (Repayments of) Debt, Total Underwriting discounts Underwriting Discounts Underwriting discounts. Debt Investments, Range Debt Instrument, Measurement Input Total dividend income Total dividend income Dividend Income, Operating November 2026 Notes 3.50% Notes Due 2026 Three Point Five Zero Percent Notes Due Two Thousand Twenty Six [Member] Three point five zero percent notes due two thousand twenty six. Ipro Tech, LLC Ipro Tech, LLC [Member] Ipro tech, LLC. Variable Index Spread Investment Variable Index Spread Rate Investment variable index spread rate. Fair Value Estimate of Fair Value Measurement [Member] Deferred Financing Costs Excluding Secured Borrowings, Total Deferred financing costs excluding secured borrowings. Deferred Financing Costs Excluding Secured Borrowings Debt, net of deferred financing costs 2028 Long-Term Debt, Maturity, Year Five Gross Reductions Gross Reductions Investments in and Advances to Affiliates, at Fair Value, Gross Reductions Total expenses before base management fee waiver Operating Expenses Combined Systems, Inc. - Revolving Loan Combined Systems, Inc. - Revolving Loan [Member] Combined Systems, Inc. - revolving loan. 2024 Long-Term Debt, Maturity, Year One Cardback Intermediate L L C Cardback Intermediate L L C [Member] Cardback intermediate LLC. Number of operating segments Number of Operating Segments Business Services Business Services [Member] Business services. Investment Type [Axis] Utilities services. Utilities Services [Member] Utilities: Services Dividends Payable [Line Items] Credit facility, interest rate per annum Unused commitment fee rate, period end Unused portion of Credit Facility commitment percentage Gross proceeds received Gross Proceeds Gross Proceeds From Issuance Of Common Stock Under At The Market Program Gross proceeds from issuance of common stock under at the market program. Payments to Acquire Investments Purchases of debt and equity investments Purchases of debt and equity investments Investment, Acquisition Date Investment Date Investment acquisition date K2 Merger Agreement Agent, LLC (fka K2 Industrial Services, Inc.) K2 Merger Agreement Agent LLC [Member] K2 merger agreement agent LLC. Building Products Manufacturing Building Products Manufacturing [Member] Building products manufacturing. Proceeds from sales and repayments of investments Proceeds from Sales and Repayments of Investments Proceeds from sales and repayments of investments. 5.439% Fixed Interest Rate Five Point Four Three Nine Percent Interest Rate One [Member] Five point four three nine percent interest rate one. Total Commitment Contractual Obligation Contractual Obligation, Total Summary of Equity ATM Program Summary Of Common Stock ATM Program 1 [Table Text Block] Summary of common Sstock ATM program. Notes underwriting discounts Underwriting discounts Deferred Underwriting Discounts Deferred underwriting discounts. Financial Highlights Investment Company, Financial Highlights [Text Block] Quarterly Dividend Quarterly Dividend [Member] Quarterly dividend. Credit facility commitment percentage Line of Credit Facility, Commitment Fee Percentage Subsequent Event Type [Domain] 2026 Long-Term Debt, Maturity, Year Three Incentive fee - income Incentive Fee Expense Underwriting fees and commissions under at the market program. Underwriting Fees And Commissions Under At The Market Program Underwriting Fees and Commissions Management fees annual rate Management Fees Annual Rate Percentage Management fees annual rate percentage. Long-Term Debt, Type [Axis] Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net increase (decrease) in net assets resulting from operations United States Southeast United States Southeast [Member] United States Southeast. Line of Credit Facility, Lender [Domain] Interest rate payment term Debt Instrument, Frequency of Periodic Payment Level 2 Fair Value, Inputs, Level 2 [Member] 2.377% Fixed Interest Rate Two Point Three Seven Seven Percent Interest Rate [Member] Two point three seven seven percent interest rate. Interest on idle funds Interest on Idle Funds Interest on idle funds. Market value at end of period Fair value assets level two to level one transfers amount. Fair Value Assets Level Two To Level One Transfers Amount Fair value, assets, level 2 to level 1 transfers, amount Credit Agreement Senior Secured Revolving Credit Agreement [Member] Senior secured revolving credit agreement. 5.861% Fixed Interest Rate Five Point Eight Six One Percent Interest Rate Two [Member] Five point eight six one percent interest rate two Dividends Payable [Table] Five point nine eight three percent interest rate. Five Point Nine Eight Three Percent Interest Rate [Member] 5.983% Fixed Interest Rate Debt obligations carrying value Outstanding debt Long-Term Debt, Gross Fishbowl Solutions Llc Fishbowl Solutions, LLC [Member] Fishbowl Solutions, LLC. Net investment income Investment Company, Investment Income (Loss) Ratio Base management fee Management Fee Expense Equity Equity Securities [Member] Common equity Total Distributable Earnings Accumulated Distributions in Excess of Net Income [Member] Industry Sector [Domain] Money Market Funds, at Carrying Value Cost Debt instrument asset coverage percentage Debt Instrument Asset Coverage Percentage Debt Instrument Asset Coverage Percentage Aggregate amount of outstanding of senior securities Aggregate Amount of Outstanding of Senior Securities Aggregate amount of outstanding of senior securities. American AllWaste LLC American AllWaste LLC [Member] American AllWaste LLC. Investments [Domain] Accretion of original issue discount Accretion of Original Issue Discount Accretion of original issue discount. Dividends to stockholders Investment Company Dividends To Stockholders Per Share Investment company, dividends to stockholders per share. Subordinated Debt Subordinated Debt [Member] Schedule of Investments [Table] Schedule of Investments [Line Items] Amortization of deferred financing costs Amortization of Debt Issuance Costs Carrying Value Cost Reported Value Measurement [Member] Summary of Outstanding Debt Net of Unamortized Deferred Financing Costs Summary of Unamortized Deferred Financing Costs [Table Text Block] Summary of unamortized deferred financing costs. Debt, net of deferred financing costs Debt, net of deferred financing costs Borrowings under Credit Facility, net of deferred financing costs (Note 6) Borrowings under Credit Facility, net of deferred financing costs (Note 6) Long-Term Line of Credit Long-term Line of Credit, Total Segments Segment Reporting, Policy [Policy Text Block] Portion at Fair Value Measurement [Member] [Default] Portion at Fair Value Measurement [Member] Base management fee waiver Investment Company Base Management Fee Waiver Investment company, base management fee waiver. Subsequent Event [Table] Dividends declared per share Common Stock, Dividends, Per Share, Declared Total payment-in-kind interest income Paid-In-Kind Interest Income Paid-in-kind interest income Base management fee payable, net of base management fee waiver - due to affiliate Increase Decrease In Base Management Fee Payable Increase decrease in base management fee payable. Gross Additions Investments in and Advances to Affiliates, at Fair Value, Gross Additions Net investment income Investment Income (Expense), Net after tax Investment Income (Expense), Net after tax Net investment income Common Stock, shares outstanding Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding, Ending Balance Common Stock, Shares, Outstanding, Beginning Balance Fee Income Investment Income Fee Income Investment income fee income. Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Debt investments in portfolio companies on non-accrual status Debt Investment In Number Of Portfolio Companies On Non Accrual Status Debt investment in number of portfolio companies on non-accrual status. Warrants Warrants Policy Text Block Warrants policy text block. Investment, Identifier [Axis] Fair value assets level one to level two transfers amount. Fair Value Assets Level One To Level Two Transfers Amount Fair value, assets, level 1 to level 2 transfers, amount Revenue Multiples Measurement Input, Revenue Multiple [Member] SBA debenture commitment fees Commitment fees Debt Instrument, Fee Amount Credit Facility Line of Credit [Member] 2.172% Fixed Interest Rate Two Point One Seven Two Percent Interest Rate [Member] Two point one seven two percent interest rate. Investment interest rate Investment interest rate, Cash Investment Interest Rate Mesa Line Services, LLC Mesa Line Services LLC [Member] Mesa line services LLC. Percentage of taxable income Percentage Of Taxable Income Percentage of taxable income. Prepaid expenses and other assets Prepaid Expense and Other Assets Net asset value per common share Net asset value at beginning of period Net asset value at end of period Net cash provided by (used for) financing activities Net cash provided by (used for) financing activities Total interest income Total interest income Interest Income, Operating Western's Smokehouse, LLC - Delayed Draw Term Loan. Western's Smokehouse, LLC - Delayed Draw Term Loan [Member] Western's Smokehouse, LLC - Delayed Draw Term Loan Limited Partnership Agreement Limited Partnership Agreement [Member] Limited partnership agreement. Payment percentage of preincentive fees net investment income Payment Percentage of PreIncentive Fees Net Investment Income Payment percentage of preincentive fees net investment income. Interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Investments and money market funds owned at fair value. Investments and Money Market Funds Owned at Fair Value Fair Value Weighted average effective yield investment percentage Debt Securities, Available-for-Sale, Weighted Average Yield, Maturity, Year One Special Dividend Special dividend. Variable Rate [Axis] Administration Agreement Administration Agreement [Member] Administration agreement. NWS Technologies, LLC. NWS Technologies, LLC [Member] NWS Technologies, LLC Total liabilities Liabilities Dividends and Distributions Dividends and Distributions [Text Block] Dividends and distributions. Interest receivable Interest Receivable Total expenses, before base management fee waiver Investment Company Expenses Ratio Before Base Management Fee Waiver Investment company, expenses ratio before base management fee waiver. Isi Psg Holdings LLC ISI PSG Holdings, LLC [Member] ISI PSG holdings, LLC. Interest and dividend income paid-in-kind Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Interest And Dividend Income Paid-In-Kind Fair value measurement with unobservable inputs reconciliation recurring basis asset, interest and dividend income paid-in-kind. Total net assets Net assets at end of period Ending balance Beginning balance Equity, Attributable to Parent ING Capital LLC ING Capital Limited Liability Company [Member] ING Capital LLC. SOFR Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] Payment Date Dividends Payable, Date to be Paid Dividend payable date Number of investments represented more than ten percentage of aggregate investment portfolio Number of Investments Represented More Than Ten Percentage of Aggregate Investment Portfolio Number of Investments represented more than ten percentage of aggregate investment portfolio. Net gain (loss) on investments Net gain (loss) on investments Total fee income Fee Income Stated interest expense Interest Expense Interest Expense, Total Realized losses on extinguishment of debt Extinguishment of Debt, Gain (Loss), Per Share, Net of Tax Micronics Filtration Holdings Inc Dba Micronics Engineered Filtration Group Inc Micronics Filtration Holdings Inc dba Micronics Engineered Filtration Group Inc [Member] Micronics Filtration Holdings, Inc. (dba Micronics Engineered Filtration Group, Inc.). Realized Losses on Extinguishment of Debt Realized Losses On Extinguishment Of Debt Policy Text Block Realized losses on extinguishment of debt policy text block. United States Northeast United States Northeast [Member] United States Northeast. Fair Value of Financial Instruments Fair Value Measurement, Policy [Policy Text Block] Statement of Financial Position [Abstract] Weighted Average Number of Shares Outstanding, Diluted, Total Weighted Average Number of Shares Outstanding, Diluted Weighted average number of shares outstanding - diluted Restaurants Member Restaurants [Member] Restaurants. Realized investment gains (losses) on escrow securities not held during period. Realized Investment Gains Losses On Escrow Securities Not Held During Period Net Realized Gain (Losses) Debt instrument, redemption description Debt Instrument, Redemption, Description Credit Facility [Axis] Income Incentive fee payable Income incentive fee payable - due to affiliate income incentive fee payable due to affiliate. Elements Brands, LLC - Revolving Loan Elements Brands, LLC - Revolving Loan [Member] Elements Brands, LLC - revolving loan. DRIP Share Issue Price Shares Issued, Price Per Share PIK Income Payment In Kind Income Policy Text Block Payment in kind income policy text block. 5.341% Fixed Interest Rate Five Point Three Four One Percent Interest Rate One [Member] Five point three four one percent interest rate one. Percent of Net Assets Total net assets percentage Investment Owned, Net Assets, Percentage Non-control/Non-affiliate Investments Non Control Or Non Affiliate Investments [Member] Non control or non affiliate investments. Use of Estimates Use of Estimates, Policy [Policy Text Block] Number of Shares Purchased and Reissued Stock Issued During Period, Shares, Treasury Stock Reissued Debt instrument interim interest rate Debt Instrument Interim Interest Rate Debt instrument interim interest rate. Equity Investments, Warrants fair value Derivative Asset Derivative Asset, Total Common And Preferred Equity Units Common and Preferred Equity Units [Member] Common and preferred equity units. Waiver Waiver [Member] Waiver. Raymond James And Associates Inc And B. Riley Securities Inc Raymond James & Associates, Inc. and Robert W. Baird & Co Raymond James and Associates Inc and B. Riley Securities, Inc [Member] Raymond James and Associates Inc and B. Riley Securities, Inc. Summary of Dividends Paid Schedule of Dividends Payable [Table Text Block] Debt instrument issued amount Debt Instrument Issued Amount Debt instrument issued amount. Incentive fee (reversal) - capital gains Incentive Fee (Reversal) Capital Gains Incentive fee (reversal) capital gains. Valuation Approach and Technique [Axis] Midwest Transit Equipment, Inc. Midwest Transit Equipment, Inc. [Member] Midwest transit equipment, Inc. 5.735% Fixed Interest Rate Five Point Seven Three Five Percent Interest Rate [Member] Five point seven three five percent interest rate Fair Value Disclosures [Abstract] Fair Value Hierarchy and NAV [Axis] Measurement Frequency [Domain] 5.341% Fixed Interest Rate Five Point Three Four One Percent Interest Rate [Member] Five point three four one percent interest rate. BurgerFi International, LLC BurgerFi International, LLC [Member] BurgerFi International, LLC. Dividends to Stockholders Policyholders' Dividend [Policy Text Block] Base management fee waiver Base management fee waiver Base Management Fee Waiver Base management fee waiver. Administration fee payable and other - due to affiliate Increase Decrease Administration Fee Payable And Other Due To Affiliate Increase decrease administration fee payable and other due to affiliate. Aggregate principal amount sold Aggregate Principal Amount Of Portfolio Sold Aggregate principal amount of portfolio sold. QED Technologies International, Inc. QED Technologies International, Inc [Member] QED Technologies International, Inc [Member] Apm Intermediate Holdings Llc APM Intermediate Holdings, LLC [Member] APM intermediate holdings, LLC. Number of Shares Number of Shares Sold Public offering of common stock, net of expenses, shares End of period Beginning of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total Acendre Midco, Inc. - Revolving Loan Acendre Midco, Inc. - Revolving Loan [Member] Acendre Midco, Inc. - revolving loan. Investment Company, Financial Highlights [Table] Schedule of Debt Investment on Non-Accrual Status Investment Income [Table Text Block] Total increase from investment operations Investment Company Investment Income Loss Period Increase Decrease Investment company, investment income (loss), period increase (decrease).