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N-2 - USD ($) | 1 Months Ended | 3 Months Ended | 12 Months Ended |
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May 12, 2025 | Mar. 31, 2025 | Dec. 31, 2024 | Sep. 30, 2024 | Jun. 30, 2024 | Mar. 31, 2024 | Dec. 31, 2023 | Sep. 30, 2023 | Jun. 30, 2023 | Mar. 31, 2025 | Mar. 31, 2024 | Mar. 31, 2023 | Mar. 31, 2022 | Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2019 | Mar. 31, 2018 | Mar. 31, 2017 | Mar. 31, 2016 | Mar. 31, 2015
Cover [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Entity Central Index Key |  |  |  |  |  |  |  |  |  | 0001321741 |  |  |  |  |  |  |  |  |  |
Amendment Flag |  |  |  |  |  |  |  |  |  | false |  |  |  |  |  |  |  |  |  |
Securities Act File Number |  |  |  |  |  |  |  |  |  | 814-00704 |  |  |  |  |  |  |  |  |  |
Document Type |  |  |  |  |  |  |  |  |  | 10-K |  |  |  |  |  |  |  |  |  |
Entity Registrant Name |  |  |  |  |  |  |  |  |  | GLADSTONE INVESTMENT CORPORATION\DE |  |  |  |  |  |  |  |  |  |
Entity Address, Address Line One |  |  |  |  |  |  |  |  |  | 1521 WESTBRANCH DRIVE |  |  |  |  |  |  |  |  |  |
Entity Address, Address Line Two |  |  |  |  |  |  |  |  |  | SUITE 100 |  |  |  |  |  |  |  |  |  |
Entity Address, City or Town |  |  |  |  |  |  |  |  |  | MCLEAN |  |  |  |  |  |  |  |  |  |
Entity Address, State or Province |  |  |  |  |  |  |  |  |  | VA |  |  |  |  |  |  |  |  |  |
Entity Address, Postal Zip Code |  |  |  |  |  |  |  |  |  | 22102 |  |  |  |  |  |  |  |  |  |
City Area Code |  |  |  |  |  |  |  |  |  | 703 |  |  |  |  |  |  |  |  |  |
Local Phone Number |  |  |  |  |  |  |  |  |  | 287-5800 |  |  |  |  |  |  |  |  |  |
Entity Well-known Seasoned Issuer |  |  |  |  |  |  |  |  |  | No |  |  |  |  |  |  |  |  |  |
Entity Emerging Growth Company |  |  |  |  |  |  |  |  |  | false |  |  |  |  |  |  |  |  |  |
Fee Table [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales Load [Percent] |  |  |  |  |  |  |  |  |  | 0.00% |  |  |  |  |  |  |  |  |  |
Other Transaction Expenses [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Transaction Expense 1 [Percent] |  |  |  |  |  |  |  |  |  | 0.00% |  |  |  |  |  |  |  |  |  |
Annual Expenses [Table Text Block] |  |  |  |  |  |  |  |  |  |
Stockholder Transaction Expenses: |
Sales load or other commission (as a percentage of offering price)(1) | — | %
Offering expenses (as a percentage of offering price)(1) | — | %
Dividend reinvestment plan expenses (per sales transaction fee)(2) | Up to $25 Transaction fee
Total stockholder transaction expenses (as a percentage of offering price)(1) | —%
Annual expenses (as a percentage of net assets attributable to common stock)(3): |
Base management fee(4) | 4.18 | %
Loan servicing fee(5) | 2.28 | %
Incentive fees(6) | 3.61 | %
Interest payments on borrowed funds(7) | 7.99 | %
Other expenses(8) | 1.42 | %
Total annual expenses(9) | 19.48 | %
(1)The amounts set forth in the table above do not reflect the impact of any sales load or other commission or offering expenses borne by the Company and its common stockholders. If applicable, the prospectus or prospectus supplement relating to an offering of our common stock will disclose the offering price and the estimated offering expenses and total stockholder transaction expenses borne by the Company and its common stockholders as a percentage of the offering price. In the event that shares of our common stock are sold to or through underwriters, the applicable prospectus or prospectus supplement will also disclose the applicable sales load or other commission. (2)The expenses of the dividend reinvestment plan, if any, are included in stock record expenses, a component of “Other expenses.” If a participant elects by written notice to the plan agent prior to termination of his or her account to have the plan agent sell part or all of the shares held by the plan agent in the participant’s account and remit the proceeds to the participant, the plan agent is authorized to deduct a transaction fee, plus per share brokerage commissions, from the proceeds. The participants in the dividend reinvestment plan will also bear a transaction fee, plus per share brokerage commissions incurred with respect to open market purchases, if any. See “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Distributions and Dividends to Stockholders—Dividend Reinvestment Plan” for information on the dividend reinvestment plan. (3)The percentages presented in this table are gross of credits to any fees. (4)The base management fee is payable quarterly to the Adviser pursuant to our Advisory Agreement and is assessed at an annual rate of 2% computed on the basis of the value of our average gross assets at the end of the two most recently completed quarters (inclusive of the current quarter), which are total assets, including investments made with proceeds of borrowings, less any uninvested cash or cash equivalents resulting from borrowings, valued at the end of the applicable quarters within the respective period and adjusted appropriately for any share issuances or repurchases during the period. In accordance with the requirements of the SEC, the table above shows our base management fee as a percentage of average net assets attributable to common stockholders. For purposes of the table, the annualized base management fee has been converted to 4.18% of the average net assets for the quarter ended March 31, 2025 by dividing the total annualized amount of the base management fee by our average net assets for the quarter ended March 31, 2025. The base management fee for the quarter ended March 31, 2025 before application of any credits was $5.2 million. Pursuant to the requirements of the 1940 Act, the Adviser makes available significant managerial assistance to our portfolio companies. The Adviser may also provide other services to our portfolio companies under certain agreements and may receive fees for services other than managerial assistance. Such services may include: (i) assistance obtaining, sourcing or structuring credit facilities, long term loans or additional equity from unaffiliated third parties; (ii) negotiating important contractual financial relationships; (iii) consulting services regarding restructuring of the portfolio company and financial modeling as it relates to raising additional debt and equity capital from unaffiliated third parties; and (iv) primary role in interviewing, vetting, and negotiating employment contracts with candidates in connection with adding and retaining key portfolio company management team members. The Adviser non-contractually, unconditionally, and irrevocably credits 100% of any fees received for such services against the base management fee that we would otherwise be required to pay to the Adviser; however, pursuant to the terms of the Advisory Agreement, a small percentage of certain of such fees is retained by the Adviser in the form of reimbursement, at cost, for tasks completed by personnel of the Adviser and primarily related to the valuation of portfolio companies. For the quarter ended March 31, 2025, $1.0 million of these fees were non-contractually, unconditionally and irrevocably credited against the base management fee. See “Item 1. Business — Transactions with Related Parties — Investment Advisory and Management Agreement” for additional information. (5)The Adviser services the loans held by Business Investment in return for which the Adviser receives a 2.0% annual loan servicing fee based on the monthly aggregate balance of loans pledged under the Credit Facility. Since Business Investment is a consolidated subsidiary of ours, coupled with the fact that the total base management fee paid to the Adviser pursuant to the Advisory Agreement cannot exceed 2.0% of total assets (less any uninvested cash or cash equivalents resulting from borrowings) during any given calendar year, we treat payment of the loan servicing fee pursuant to the Credit Facility as a pre-payment of the base management fee under the Advisory Agreement. Accordingly, these loan servicing fees are 100% non-contractually, unconditionally and irrevocably credited back to us by the Adviser. The loan servicing fee for the three months ended March 31, 2025 was $2.8 million. See “Item 1. Business—Transactions with Related Parties—Loan Servicing Fee Pursuant to Credit Facility” and footnote 4 above for additional information. (6)The incentive fee payable to the Adviser under the Advisory Agreement consists of two parts: an income-based fee and a capital gains-based fee. The income-based incentive fee is payable quarterly in arrears, and equals 20% of the excess, if any, of our pre-incentive fee net investment income that exceeds a 1.75% quarterly hurdle rate of our net assets, which we define as total assets less indebtedness and before taking into account any incentive fees payable or contractually due but not payable during the period, at the end of the immediately preceding calendar quarter, adjusted appropriately for any share issuances or repurchases during the period, subject to a “catch-up” provision measured as of the end of each calendar quarter. The “catch-up” provision requires us to pay 100% of our pre-incentive fee net investment income with respect to that portion of such income, if any, that exceeds the hurdle rate but is less than 125% of the quarterly hurdle rate (or 2.1875%) in any calendar quarter. The catch-up provision is meant to provide our Adviser with 20% of our pre-incentive fee net investment income as if a hurdle rate did not apply when our pre-incentive fee net investment income exceeds 125% of the quarterly hurdle rate in any calendar quarter. For the three months ended March 31, 2025, the income-based incentive fee was $2.3 million. The capital gains-based incentive fee equals 20% of our net realized capital gains in excess of unrealized depreciation since our inception, if any, computed as all realized capital gains net of all realized capital losses and unrealized depreciation since our inception, less any prior payments, measured at the end of each calendar year and payable at the end of each fiscal year. During the three months ended March 31, 2025, we recorded capital gains-based incentive fees of $2.1 million in accordance with GAAP, which were not contractually due under the terms of the Advisory Agreement. No credits were applied to incentive fees for the three months ended March 31, 2025; however, the Adviser may credit such fees in the future. Examples of how the incentive fee would be calculated are as follows: •Assuming pre-incentive fee net investment income of 0.55%, there would be no income-based incentive fee because such income would not exceed the hurdle rate of 1.75%. •Assuming pre-incentive fee net investment income of 2.00%, the income-based incentive fee would be as follows: = 100.0% × (2.00% - 1.75%) = 0.25% •Assuming pre-incentive fee net investment income of 2.30%, the income-based incentive fee would be as follows: = (100.0% × (“catch-up”: 2.1875% - 1.75%)) + (20.0% × (2.30% - 2.1875%)) = (100.0% × 0.4375%) + (20.0% × 0.1125%) = 0.4375% + 0.0225% = 0.46% •Assuming net realized capital gains of 6% and realized capital losses and unrealized capital depreciation of 1%, the capital gains-based incentive fee would be as follows: = 20.0% × (6.0% - 1.0%) = 20.0% × 5.0% = 1.0% For a more detailed discussion of the calculation of the two-part incentive fee, including the capital gains-based incentive fee calculation under GAAP, see “Item 1. Business — Transactions with Related Parties — Investment Advisory and Management Agreement.” (7)Includes amortization of deferred financing costs. As of March 31, 2025, we had no borrowings outstanding under our Credit Facility, $127.9 million of 5.00% 2026 Notes, at cost, $134.6 million of 4.875% 2028 Notes, at cost, $74.8 million of 8.00% 2028 Notes, at cost, and $126.5 million of 7.875% 2030 Notes, at cost. See “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Revolving Line of Credit” and “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Notes Payable” for additional information regarding our Credit Facility, our 5.00% 2026 Notes, our 4.875% 2028 Notes, our 8.00% 2028 Notes and our 7.875% 2030 Notes. (8)Includes our overhead expenses, including payments under the Administration Agreement based on our projected allocable portion of overhead and other expenses estimated to be incurred by our Administrator for the current fiscal year. See “Item 1. Business—Transactions with Related Parties—Administration Agreement” for additional information. (9)Total annualized gross expenses, based on actual amounts incurred for the three months ended March 31, 2025 (except as set forth in footnote 9), would be $96.4 million. After all non-contractual, unconditional, and irrevocable credits described in footnote 4, footnote 5, and footnote 6 above are applied to the base management fee and the loan servicing fee, total annualized expenses after fee credits, based on actual amounts incurred for the three months ended March 31, 2025, would be $81.3 million or 16.44% as a percentage of average net assets. |  |  |  |  |  |  |  |  |  |
Management Fees [Percent] |  |  |  |  |  |  |  |  |  | 4.18% |  |  |  |  |  |  |  |  |  |
Interest Expenses on Borrowings [Percent] |  |  |  |  |  |  |  |  |  | 7.99% |  |  |  |  |  |  |  |  |  |
Incentive Fees [Percent] |  |  |  |  |  |  |  |  |  | 3.61% |  |  |  |  |  |  |  |  |  |
Loan Servicing Fees [Percent] |  |  |  |  |  |  |  |  |  | 2.28% |  |  |  |  |  |  |  |  |  |
Other Annual Expenses [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Annual Expenses [Percent] |  |  |  |  |  |  |  |  |  | 1.42% |  |  |  |  |  |  |  |  |  |
Expense Example [Table Text Block] |  |  |  |  |  |  |  |  |  | The following example demonstrates the projected dollar amount of total cumulative expenses that would be incurred over various periods with respect to a hypothetical investment in our common stock. In calculating the following expense amounts, we have assumed that our annual operating expenses would remain at the levels set forth in the table above. The example below and the expenses in the table above should not be considered a representation of our future expenses, and actual expenses may be greater or less than those shown. While the example assumes, as required by the SEC, a 5.0% annual return, our performance will vary and may result in a return greater or less than 5.0%. Dollar amounts in the table below are not in thousands.
| 1 Year |  | 3 Years |  | 5 Years |  | 10 Years
Common stockholders would pay the following expenses on a $1,000 investment: |  |  |  |  |  |  |
assuming a 5% annual return consisting entirely of ordinary income(1)(2) | $ | 167 |  | $ | 444 |  | $ | 660 |  | $ | 1,015
assuming a 5% annual return consisting entirely of capital gains(2)(3) | $ | 175 |  | $ | 462 |  | $ | 682 |  | $ | 1,032
(1)For purposes of this example, we have assumed that the entire amount of the assumed 5.0% annual return would constitute ordinary income. Because the assumed 5.0% annual return is significantly below the hurdle rate of 7.0% (annualized) that we must achieve under the Advisory Agreement to trigger the payment of an income-based incentive fee, we have assumed, for purposes of this example, that no income-based incentive fee would be payable if we realized a 5.0% annual return. (2)While the example assumes reinvestment of all distributions at NAV per share, participants in the dividend reinvestment plan will receive a number of shares of our common stock determined by dividing the total dollar amount of the distribution payable to a participant by the market price per share of our common stock at the close of trading on the valuation date for the distribution, and this price per share may differ from NAV per share. See “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Distributions and Dividends to Stockholders—Dividend Reinvestment Plan” for additional information regarding our dividend reinvestment plan. (3)For purposes of this example, we have assumed that the entire amount of the assumed 5.0% annual return would constitute capital gains and that no accumulated capital losses or unrealized depreciation would have to be overcome first before a capital gains-based incentive fee is payable. |  |  |  |  |  |  |  |  |  |
Expense Example, Year 01 |  |  |  |  |  |  |  |  |  | $ 167 |  |  |  |  |  |  |  |  |  |
Expense Example, Years 1 to 3 |  |  |  |  |  |  |  |  |  | 444 |  |  |  |  |  |  |  |  |  |
Expense Example, Years 1 to 5 |  |  |  |  |  |  |  |  |  | 660 |  |  |  |  |  |  |  |  |  |
Expense Example, Years 1 to 10 |  |  |  |  |  |  |  |  |  | $ 1,015 |  |  |  |  |  |  |  |  |  |
Purpose of Fee Table , Note [Text Block] |  |  |  |  |  |  |  |  |  | The following table is intended to assist stockholders in understanding the costs and expenses that common stockholders will bear directly or indirectly. The percentages indicated in the table below are estimates and may vary. Except where the context suggests otherwise, whenever this Annual Report contains a reference to fees or expenses paid by “us” or the “Company,” or that “we” will pay fees or expenses, common stockholders will indirectly bear such fees or expenses as investors in the Company. The following annualized percentages were calculated based on actual expenses, except with respect to capital gains-based incentive fees as discussed below, incurred in the quarter ended March 31, 2025 and average net assets for the quarter ended March 31, 2025. The table and examples below include all fees and expenses of our consolidated subsidiaries. |  |  |  |  |  |  |  |  |  |
Other Transaction Fees, Note [Text Block] |  |  |  |  |  |  |  |  |  | The amounts set forth in the table above do not reflect the impact of any sales load or other commission or offering expenses borne by the Company and its common stockholders. If applicable, the prospectus or prospectus supplement relating to an offering of our common stock will disclose the offering price and the estimated offering expenses and total stockholder transaction expenses borne by the Company and its common stockholders as a percentage of the offering price. In the event that shares of our common stock are sold to or through underwriters, the applicable prospectus or prospectus supplement will also disclose the applicable sales load or other commission. (2)The expenses of the dividend reinvestment plan, if any, are included in stock record expenses, a component of “Other expenses.” If a participant elects by written notice to the plan agent prior to termination of his or her account to have the plan agent sell part or all of the shares held by the plan agent in the participant’s account and remit the proceeds to the participant, the plan agent is authorized to deduct a transaction fee, plus per share brokerage commissions, from the proceeds. The participants in the dividend reinvestment plan will also bear a transaction fee, plus per share brokerage commissions incurred with respect to open market purchases, if any. See “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Distributions and Dividends to Stockholders—Dividend Reinvestment Plan” for information on the dividend reinvestment plan. |  |  |  |  |  |  |  |  |  |
Other Expenses, Note [Text Block] |  |  |  |  |  |  |  |  |  | Includes our overhead expenses, including payments under the Administration Agreement based on our projected allocable portion of overhead and other expenses estimated to be incurred by our Administrator for the current fiscal year. See “Item 1. Business—Transactions with Related Parties—Administration Agreement” for additional information. |  |  |  |  |  |  |  |  |  |
Management Fee not based on Net Assets, Note [Text Block] |  |  |  |  |  |  |  |  |  | The base management fee is payable quarterly to the Adviser pursuant to our Advisory Agreement and is assessed at an annual rate of 2% computed on the basis of the value of our average gross assets at the end of the two most recently completed quarters (inclusive of the current quarter), which are total assets, including investments made with proceeds of borrowings, less any uninvested cash or cash equivalents resulting from borrowings, valued at the end of the applicable quarters within the respective period and adjusted appropriately for any share issuances or repurchases during the period. In accordance with the requirements of the SEC, the table above shows our base management fee as a percentage of average net assets attributable to common stockholders. For purposes of the table, the annualized base management fee has been converted to 4.18% of the average net assets for the quarter ended March 31, 2025 by dividing the total annualized amount of the base management fee by our average net assets for the quarter ended March 31, 2025. The base management fee for the quarter ended March 31, 2025 before application of any credits was $5.2 million. Pursuant to the requirements of the 1940 Act, the Adviser makes available significant managerial assistance to our portfolio companies. The Adviser may also provide other services to our portfolio companies under certain agreements and may receive fees for services other than managerial assistance. Such services may include: (i) assistance obtaining, sourcing or structuring credit facilities, long term loans or additional equity from unaffiliated third parties; (ii) negotiating important contractual financial relationships; (iii) consulting services regarding restructuring of the portfolio company and financial modeling as it relates to raising additional debt and equity capital from unaffiliated third parties; and (iv) primary role in interviewing, vetting, and negotiating employment contracts with candidates in connection with adding and retaining key portfolio company management team members. The Adviser non-contractually, unconditionally, and irrevocably credits 100% of any fees received for such services against the base management fee that we would otherwise be required to pay to the Adviser; however, pursuant to the terms of the Advisory Agreement, a small percentage of certain of such fees is retained by the Adviser in the form of reimbursement, at cost, for tasks completed by personnel of the Adviser and primarily related to the valuation of portfolio companies. For the quarter ended March 31, 2025, $1.0 million of these fees were non-contractually, unconditionally and irrevocably credited against the base management fee. See “Item 1. Business — Transactions with Related Parties — Investment Advisory and Management Agreement” for additional information. |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities [Table Text Block] |  |  |  |  |  |  |  |  |  |
Class and Year | Total Amount Outstanding Exclusive of Treasury Securities (1) |  | Asset Coverage Per Unit (2) |  | Involuntary Liquidating Preference Per Unit (3) |  | Average Market Value Per Unit (4)
7.125% Series A Cumulative Term Preferred Stock(5) |  |  |  |  |  |  |
March 31, 2016 | $ | 40,000,000 |  |  | $ | 2,214 |  |  | $ | 25.00 |  |  | $ | 25.60 |
6.75% Series B Cumulative Term Preferred Stock(6) |  |  |  |  |  |  |
March 31, 2018 | $ | 41,400,000 |  |  | $ | 2,373 |  |  | $ | 25.00 |  |  | $ | 25.20 |
March 31, 2017 | $ | 41,400,000 |  |  | $ | 2,356 |  |  | $ | 25.00 |  |  | $ | 26.00 |
March 31, 2016 | $ | 41,400,000 |  |  | $ | 2,214 |  |  | $ | 25.00 |  |  | $ | 24.43 |
6.50% Series C Cumulative Term Preferred Stock due 2022(7) |  |  |  |  |  |
March 31, 2018 | $ | 40,250,000 |  |  | $ | 2,373 |  |  | $ | 25.00 |  |  | $ | 25.33 |
March 31, 2017 | $ | 40,250,000 |  |  | $ | 2,356 |  |  | $ | 25.00 |  |  | $ | 25.64 |
March 31, 2016 | $ | 40,250,000 |  |  | $ | 2,214 |  |  | $ | 25.00 |  |  | $ | 23.92 |
6.25% Series D Cumulative Term Preferred Stock due 2023(8) |  |  |  |  |  |
March 31, 2020 | $ | 57,500,000 |  |  | $ | 2,938 |  |  | $ | 25.00 |  |  | $ | 20.46 |
March 31, 2019 | $ | 57,500,000 |  |  | $ | 3,091 |  |  | $ | 25.00 |  |  | $ | 25.38 |
March 31, 2018 | $ | 57,500,000 |  |  | $ | 2,373 |  |  | $ | 25.00 |  |  | $ | 25.22 |
March 31, 2017 | $ | 57,500,000 |  |  | $ | 2,356 |  |  | $ | 25.00 |  |  | $ | 25.43 |
6.375% Series E Cumulative Term Preferred Stock due 2025(9) |  |  |  |  |  |
March 31, 2021 | $ | 94,371,325 |  |  | $ | 2,486 |  |  | $ | 25.00 |  |  | $ | 25.44 |
March 31, 2020 | $ | 74,750,000 |  |  | $ | 2,938 |  |  | $ | 25.00 |  |  | $ | 19.52 |
March 31, 2019 | $ | 74,750,000 |  |  | $ | 3,091 |  |  | $ | 25.00 |  |  | $ | 25.55 |
Revolving credit facilities |  |  |  |  |  |  |
March 31, 2025 | $ | — |  |  | $ | 2,044 |  |  | — |  |  | N/A
March 31, 2024 | $ | 67,000,000 |  |  | $ | 2,190 |  |  | — |  |  | N/A
March 31, 2023 | $ | 35,200,000 |  |  | $ | 2,447 |  |  | — |  |  | N/A
March 31, 2022 | $ | — |  |  | $ | 2,529 |  |  | — |  |  | N/A
March 31, 2021 | $ | 22,400,000 |  |  | $ | 3,980 |  |  | — |  |  | N/A
March 31, 2020 | $ | 49,200,000 |  |  | $ | 9,935 |  |  | — |  |  | N/A
March 31, 2019 | $ | 53,000,000 |  |  | $ | 9,976 |  |  | — |  |  | N/A
March 31, 2018 | $ | 107,000,000 |  |  | $ | 5,257 |  |  | — |  |  | N/A
March 31, 2017 | $ | 69,700,000 |  |  | $ | 6,613 |  |  | — |  |  | N/A
March 31, 2016 | $ | 95,000,000 |  |  | $ | 4,838 |  |  | — |  |  | N/A
5.00% 2026 Notes(10) |  |  |  |  |  |  |
March 31, 2025 | $ | 127,937,500 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 24.93 |
March 31, 2024 | $ | 127,937,500 |  |  | $ | 2,190 |  |  | $ | 25.00 |  |  | $ | 24.16 |
March 31, 2023 | $ | 127,937,500 |  |  | $ | 2,447 |  |  | $ | 25.00 |  |  | $ | 23.47 |
March 31, 2022 | $ | 127,937,500 |  |  | $ | 2,529 |  |  | $ | 25.00 |  |  | $ | 25.13 |
March 31, 2021 | $ | 127,937,500 |  |  | $ | 3,980 |  |  | $ | 25.00 |  |  | $ | 25.85 |
Class and Year | Total Amount Outstanding Exclusive of Treasury Securities (1) |  | Asset Coverage Per Unit (2) |  | Involuntary Liquidating Preference Per Unit (3) |  | Average Market Value Per Unit (4)
4.875% 2028 Notes(11) |  |  |  |  |  |  |
March 31, 2025 | $ | 134,550,000 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 23.33 |
March 31, 2024 | $ | 134,550,000 |  |  | $ | 2,190 |  |  | $ | 25.00 |  |  | $ | 22.95 |
March 31, 2023 | $ | 134,550,000 |  |  | $ | 2,447 |  |  | $ | 25.00 |  |  | $ | 23.00 |
March 31, 2022 | $ | 134,550,000 |  |  | $ | 2,529 |  |  | $ | 25.00 |  |  | $ | 25.07 |
8.00% 2028 Notes(12) |  |  |  |  |  |  |
March 31, 2025 | $ | 74,750,000 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 25.86 |
March 31, 2024 | $ | 74,750,000 |  |  | $ | 2,190 |  |  | $ | 25.00 |  |  | $ | 25.86 |
7.875% 2030 Notes(13) |  |  |  |  |  |  |
March 31, 2025 | $ | 126,500,000 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 25.38 |
Secured borrowings(14) |  |  |  |  |  |  |
March 31, 2022 | $ | 5,095,785 |  |  | $ | 2,529 |  |  | — |  |  | N/A
March 31, 2021 | $ | 5,095,785 |  |  | $ | 3,980 |  |  | — |  |  | N/A
March 31, 2020 | $ | 5,095,785 |  |  | $ | 9,935 |  |  | — |  |  | N/A
March 31, 2019 | $ | 5,095,785 |  |  | $ | 9,976 |  |  | — |  |  | N/A
March 31, 2018 | $ | 5,095,785 |  |  | $ | 5,257 |  |  | — |  |  | N/A
March 31, 2017 | $ | 5,095,785 |  |  | $ | 6,613 |  |  | — |  |  | N/A
March 31, 2016 | $ | 5,095,785 |  |  | $ | 4,838 |  |  | — |  |  | N/A
(1)Total amount of each class of senior securities outstanding as of the dates presented. (2)Asset coverage is the ratio of the carrying value of our total consolidated assets, less all liabilities and indebtedness not represented by senior securities, to the aggregate amount of senior securities representing indebtedness (including interest payable and guaranties). Asset coverage per unit is the asset coverage ratio expressed in terms of dollar amounts per one thousand dollars of indebtedness. (3)The amount to which such class of senior security would be entitled upon the involuntary liquidation of the issuer in preference to any security junior to it. (4)Only applicable to our Term Preferred Stock and the Notes because the other senior securities are not registered for public trading. Average market value per unit is the average of the closing price of the shares on Nasdaq during the last 10 trading days of the period. (5)Our Series A Term Preferred Stock was issued in March 2012 and redeemed in September 2016. (6)Our Series B Term Preferred Stock was issued in November 2014 and redeemed in August 2018. (7)Our Series C Term Preferred Stock was issued in May 2015 and redeemed in August 2018. (8)Our Series D Term Preferred Stock was issued in September 2016 and redeemed in March 2021. (9)Our Series E Term Preferred Stock was issued in August 2018 and redeemed in August 2021. (10)Our 5.00% 2026 Notes were issued in March 2021. (11)Our 4.875% 2028 Notes were issued in August 2021. (12)Our 8.00% 2028 Notes were issued in May 2023. (13)Our 7.875% 2030 Notes were issued in December 2024. (14)In August 2012, we entered into a participation agreement with a third-party related to $5.0 million of our secured second lien term debt investment in Ginsey Home Solutions, Inc. (“Ginsey”). In May 2014, we amended the agreement with the third-party to include an additional $0.1 million. Accounting Standards Codification Topic 860, “Transfers and Servicing” requires us to treat the participation as a financing-type transaction. Specifically, the third-party has a senior claim to our remaining investment in the event of default by Ginsey which, in part, resulted in the loan participation bearing a rate of interest lower than the contractual rate established at origination. In conjunction with the August 2022 refinancing at Ginsey, the $5.1 million secured borrowing liability was extinguished. |  |  |  |  |  |  |  |  |  |
Senior Securities, Note [Text Block] |  |  |  |  |  |  |  |  |  | Senior Securities Information about our senior securities is shown in the following table as of the end of each of our last ten fiscal years. The annual information has been derived from our audited financial statements for each respective period, which have been audited by PricewaterhouseCoopers LLP, our independent registered public accounting firm. The report of our independent registered public accounting firm, PricewaterhouseCoopers LLP, on the senior securities table as of March 31, 2025 is included elsewhere in this Annual Report.
Class and Year | Total Amount Outstanding Exclusive of Treasury Securities (1) |  | Asset Coverage Per Unit (2) |  | Involuntary Liquidating Preference Per Unit (3) |  | Average Market Value Per Unit (4)
7.125% Series A Cumulative Term Preferred Stock(5) |  |  |  |  |  |  |
March 31, 2016 | $ | 40,000,000 |  |  | $ | 2,214 |  |  | $ | 25.00 |  |  | $ | 25.60 |
6.75% Series B Cumulative Term Preferred Stock(6) |  |  |  |  |  |  |
March 31, 2018 | $ | 41,400,000 |  |  | $ | 2,373 |  |  | $ | 25.00 |  |  | $ | 25.20 |
March 31, 2017 | $ | 41,400,000 |  |  | $ | 2,356 |  |  | $ | 25.00 |  |  | $ | 26.00 |
March 31, 2016 | $ | 41,400,000 |  |  | $ | 2,214 |  |  | $ | 25.00 |  |  | $ | 24.43 |
6.50% Series C Cumulative Term Preferred Stock due 2022(7) |  |  |  |  |  |
March 31, 2018 | $ | 40,250,000 |  |  | $ | 2,373 |  |  | $ | 25.00 |  |  | $ | 25.33 |
March 31, 2017 | $ | 40,250,000 |  |  | $ | 2,356 |  |  | $ | 25.00 |  |  | $ | 25.64 |
March 31, 2016 | $ | 40,250,000 |  |  | $ | 2,214 |  |  | $ | 25.00 |  |  | $ | 23.92 |
6.25% Series D Cumulative Term Preferred Stock due 2023(8) |  |  |  |  |  |
March 31, 2020 | $ | 57,500,000 |  |  | $ | 2,938 |  |  | $ | 25.00 |  |  | $ | 20.46 |
March 31, 2019 | $ | 57,500,000 |  |  | $ | 3,091 |  |  | $ | 25.00 |  |  | $ | 25.38 |
March 31, 2018 | $ | 57,500,000 |  |  | $ | 2,373 |  |  | $ | 25.00 |  |  | $ | 25.22 |
March 31, 2017 | $ | 57,500,000 |  |  | $ | 2,356 |  |  | $ | 25.00 |  |  | $ | 25.43 |
6.375% Series E Cumulative Term Preferred Stock due 2025(9) |  |  |  |  |  |
March 31, 2021 | $ | 94,371,325 |  |  | $ | 2,486 |  |  | $ | 25.00 |  |  | $ | 25.44 |
March 31, 2020 | $ | 74,750,000 |  |  | $ | 2,938 |  |  | $ | 25.00 |  |  | $ | 19.52 |
March 31, 2019 | $ | 74,750,000 |  |  | $ | 3,091 |  |  | $ | 25.00 |  |  | $ | 25.55 |
Revolving credit facilities |  |  |  |  |  |  |
March 31, 2025 | $ | — |  |  | $ | 2,044 |  |  | — |  |  | N/A
March 31, 2024 | $ | 67,000,000 |  |  | $ | 2,190 |  |  | — |  |  | N/A
March 31, 2023 | $ | 35,200,000 |  |  | $ | 2,447 |  |  | — |  |  | N/A
March 31, 2022 | $ | — |  |  | $ | 2,529 |  |  | — |  |  | N/A
March 31, 2021 | $ | 22,400,000 |  |  | $ | 3,980 |  |  | — |  |  | N/A
March 31, 2020 | $ | 49,200,000 |  |  | $ | 9,935 |  |  | — |  |  | N/A
March 31, 2019 | $ | 53,000,000 |  |  | $ | 9,976 |  |  | — |  |  | N/A
March 31, 2018 | $ | 107,000,000 |  |  | $ | 5,257 |  |  | — |  |  | N/A
March 31, 2017 | $ | 69,700,000 |  |  | $ | 6,613 |  |  | — |  |  | N/A
March 31, 2016 | $ | 95,000,000 |  |  | $ | 4,838 |  |  | — |  |  | N/A
5.00% 2026 Notes(10) |  |  |  |  |  |  |
March 31, 2025 | $ | 127,937,500 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 24.93 |
March 31, 2024 | $ | 127,937,500 |  |  | $ | 2,190 |  |  | $ | 25.00 |  |  | $ | 24.16 |
March 31, 2023 | $ | 127,937,500 |  |  | $ | 2,447 |  |  | $ | 25.00 |  |  | $ | 23.47 |
March 31, 2022 | $ | 127,937,500 |  |  | $ | 2,529 |  |  | $ | 25.00 |  |  | $ | 25.13 |
March 31, 2021 | $ | 127,937,500 |  |  | $ | 3,980 |  |  | $ | 25.00 |  |  | $ | 25.85 |
Class and Year | Total Amount Outstanding Exclusive of Treasury Securities (1) |  | Asset Coverage Per Unit (2) |  | Involuntary Liquidating Preference Per Unit (3) |  | Average Market Value Per Unit (4)
4.875% 2028 Notes(11) |  |  |  |  |  |  |
March 31, 2025 | $ | 134,550,000 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 23.33 |
March 31, 2024 | $ | 134,550,000 |  |  | $ | 2,190 |  |  | $ | 25.00 |  |  | $ | 22.95 |
March 31, 2023 | $ | 134,550,000 |  |  | $ | 2,447 |  |  | $ | 25.00 |  |  | $ | 23.00 |
March 31, 2022 | $ | 134,550,000 |  |  | $ | 2,529 |  |  | $ | 25.00 |  |  | $ | 25.07 |
8.00% 2028 Notes(12) |  |  |  |  |  |  |
March 31, 2025 | $ | 74,750,000 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 25.86 |
March 31, 2024 | $ | 74,750,000 |  |  | $ | 2,190 |  |  | $ | 25.00 |  |  | $ | 25.86 |
7.875% 2030 Notes(13) |  |  |  |  |  |  |
March 31, 2025 | $ | 126,500,000 |  |  | $ | 2,044 |  |  | $ | 25.00 |  |  | $ | 25.38 |
Secured borrowings(14) |  |  |  |  |  |  |
March 31, 2022 | $ | 5,095,785 |  |  | $ | 2,529 |  |  | — |  |  | N/A
March 31, 2021 | $ | 5,095,785 |  |  | $ | 3,980 |  |  | — |  |  | N/A
March 31, 2020 | $ | 5,095,785 |  |  | $ | 9,935 |  |  | — |  |  | N/A
March 31, 2019 | $ | 5,095,785 |  |  | $ | 9,976 |  |  | — |  |  | N/A
March 31, 2018 | $ | 5,095,785 |  |  | $ | 5,257 |  |  | — |  |  | N/A
March 31, 2017 | $ | 5,095,785 |  |  | $ | 6,613 |  |  | — |  |  | N/A
March 31, 2016 | $ | 5,095,785 |  |  | $ | 4,838 |  |  | — |  |  | N/A
(1)Total amount of each class of senior securities outstanding as of the dates presented. (2)Asset coverage is the ratio of the carrying value of our total consolidated assets, less all liabilities and indebtedness not represented by senior securities, to the aggregate amount of senior securities representing indebtedness (including interest payable and guaranties). Asset coverage per unit is the asset coverage ratio expressed in terms of dollar amounts per one thousand dollars of indebtedness. (3)The amount to which such class of senior security would be entitled upon the involuntary liquidation of the issuer in preference to any security junior to it. (4)Only applicable to our Term Preferred Stock and the Notes because the other senior securities are not registered for public trading. Average market value per unit is the average of the closing price of the shares on Nasdaq during the last 10 trading days of the period. (5)Our Series A Term Preferred Stock was issued in March 2012 and redeemed in September 2016. (6)Our Series B Term Preferred Stock was issued in November 2014 and redeemed in August 2018. (7)Our Series C Term Preferred Stock was issued in May 2015 and redeemed in August 2018. (8)Our Series D Term Preferred Stock was issued in September 2016 and redeemed in March 2021. (9)Our Series E Term Preferred Stock was issued in August 2018 and redeemed in August 2021. (10)Our 5.00% 2026 Notes were issued in March 2021. (11)Our 4.875% 2028 Notes were issued in August 2021. (12)Our 8.00% 2028 Notes were issued in May 2023. (13)Our 7.875% 2030 Notes were issued in December 2024. (14)In August 2012, we entered into a participation agreement with a third-party related to $5.0 million of our secured second lien term debt investment in Ginsey Home Solutions, Inc. (“Ginsey”). In May 2014, we amended the agreement with the third-party to include an additional $0.1 million. Accounting Standards Codification Topic 860, “Transfers and Servicing” requires us to treat the participation as a financing-type transaction. Specifically, the third-party has a senior claim to our remaining investment in the event of default by Ginsey which, in part, resulted in the loan participation bearing a rate of interest lower than the contractual rate established at origination. In conjunction with the August 2022 refinancing at Ginsey, the $5.1 million secured borrowing liability was extinguished. |  |  |  |  |  |  |  |  |  |
Senior Securities Averaging Method, Note [Text Block] |  |  |  |  |  |  |  |  |  | Only applicable to our Term Preferred Stock and the Notes because the other senior securities are not registered for public trading. Average market value per unit is the average of the closing price of the shares on Nasdaq during the last 10 trading days of the period. |  |  |  |  |  |  |  |  |  |
Senior Securities Headings, Note [Text Block] |  |  |  |  |  |  |  |  |  | Total amount of each class of senior securities outstanding as of the dates presented. (2)Asset coverage is the ratio of the carrying value of our total consolidated assets, less all liabilities and indebtedness not represented by senior securities, to the aggregate amount of senior securities representing indebtedness (including interest payable and guaranties). Asset coverage per unit is the asset coverage ratio expressed in terms of dollar amounts per one thousand dollars of indebtedness. (3)The amount to which such class of senior security would be entitled upon the involuntary liquidation of the issuer in preference to any security junior to it. (4)Only applicable to our Term Preferred Stock and the Notes because the other senior securities are not registered for public trading. Average market value per unit is the average of the closing price of the shares on Nasdaq during the last 10 trading days of the period. (5)Our Series A Term Preferred Stock was issued in March 2012 and redeemed in September 2016. (6)Our Series B Term Preferred Stock was issued in November 2014 and redeemed in August 2018. (7)Our Series C Term Preferred Stock was issued in May 2015 and redeemed in August 2018. (8)Our Series D Term Preferred Stock was issued in September 2016 and redeemed in March 2021. (9)Our Series E Term Preferred Stock was issued in August 2018 and redeemed in August 2021. (10)Our 5.00% 2026 Notes were issued in March 2021. (11)Our 4.875% 2028 Notes were issued in August 2021. (12)Our 8.00% 2028 Notes were issued in May 2023. (13)Our 7.875% 2030 Notes were issued in December 2024. (14)In August 2012, we entered into a participation agreement with a third-party related to $5.0 million of our secured second lien term debt investment in Ginsey Home Solutions, Inc. (“Ginsey”). In May 2014, we amended the agreement with the third-party to include an additional $0.1 million. Accounting Standards Codification Topic 860, “Transfers and Servicing” requires us to treat the participation as a financing-type transaction. Specifically, the third-party has a senior claim to our remaining investment in the event of default by Ginsey which, in part, resulted in the loan participation bearing a rate of interest lower than the contractual rate established at origination. In conjunction with the August 2022 refinancing at Ginsey, the $5.1 million secured borrowing liability was extinguished. |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment Objectives and Practices [Text Block] |  |  |  |  |  |  |  |  |  | Investment Objectives and Strategy We were established for the purpose of investing in debt and equity securities of established private businesses operating in the United States ("U.S."). Our investment objectives are to: (i) achieve and grow current income by investing in debt securities of established businesses that we believe will provide stable earnings and cash flow to pay expenses, make principal and interest payments on our outstanding indebtedness and make distributions to stockholders that grow over time; and (ii) provide our stockholders with long-term capital appreciation in the value of our assets by investing in equity securities of established businesses, generally in combination with the aforementioned debt securities, that we believe can grow over time to permit us to sell our equity investments for capital gains. To achieve our investment objectives, our investment strategy is to invest in several categories of debt and equity securities, with individual investments in a particular portfolio company generally totaling up to $75 million, although investment size may vary, depending upon our total assets or available capital at the time of investment. We expect that our investment portfolio over time will consist of approximately 75% in debt investments and 25% in equity investments, at cost. As of March 31, 2025, our investment portfolio was comprised of 73.3% in debt investments and 26.7% in equity investments, at cost. We focus on investing in lower middle market private businesses (which we generally define as private companies with annual earnings before interest, taxes, depreciation and amortization (“EBITDA”) of $4 million to $15 million) (“Lower Middle Market”) in the U.S. that meet certain criteria, including: the sustainability of the business’ free cash flow and its ability to grow it over time, adequate assets for loan collateral, experienced management teams with a significant ownership interest in the portfolio company, reasonable capitalization of the portfolio company, including an ample equity contribution or cushion based on prevailing enterprise valuation multiples, and the potential to realize appreciation and gain liquidity in our equity position, if any. We anticipate that liquidity in our equity position will be achieved through a merger, acquisition, or recapitalization of the portfolio company, a public offering of the portfolio company’s stock or, to a lesser extent, by exercising our right to require the portfolio company to repurchase our warrants, as applicable, though there can be no assurance that we will always have these rights. We invest in portfolio companies that seek funds for management buyouts and/or growth capital to finance acquisitions, recapitalize or, to a lesser extent, refinance their existing debt facilities. We invest by ourselves or jointly with other funds and/or management of the portfolio company, depending on the opportunity. In July 2012, the SEC granted us an exemptive order (the “Co-Investment Order”) that expanded our ability to co-invest, under certain circumstances, with certain of our affiliates, including Gladstone Capital and Gladstone Alternative and any future BDC or registered closed-end management investment company that is advised (or sub-advised if it controls the fund) by the Adviser, or any combination of the foregoing, subject to the conditions in the Co-Investment Order. We believe the Co-Investment Order has enhanced and will continue to enhance our ability to further our investment objectives and strategies. If we are participating in an investment with one or more co-investors, whether or not an affiliate of ours, our investment is likely to be smaller than if we were investing alone. In general, our investments in debt securities have a term of five years, accrue interest at variable rates based on the 30 day Secured Overnight Financing Rate ("SOFR") and, to a lesser extent, at fixed rates. As of March 31, 2025, our loan portfolio consisted of 100.0% variable rate loans with floors, based on the total principal balance of all outstanding debt investments. We seek debt instruments that pay interest monthly or, at a minimum, quarterly, and which may include a yield enhancement such as a success fee or, to a lesser extent, deferred interest provision and are primarily interest only, with all principal and any accrued but unpaid interest due at maturity. Generally, success fees accrue at a set rate and are contractually due upon a change of control of the portfolio company. Some debt securities may have deferred interest whereby some portion of the interest payment is added to the principal balance so that the interest is paid, together with the principal, at maturity. This form of deferred interest is often called “paid-in-kind” (“PIK”) interest. As of March 31, 2025, we did not have any securities with a PIK feature. Typically, our investments in equity securities take the form of common stock, preferred stock, limited liability company interests, warrants or options to purchase any of the foregoing. Often, these equity investments occur in connection with our original investment, buyouts and recapitalizations of a business, or refinancing existing debt. From our initial public offering in 2005 through March 31, 2025, we invested in 62 companies, excluding investments in syndicated loans. We expect that our investment portfolio will continue to primarily include the following three categories of investments in private companies in the U.S.: •Secured First Lien Debt Securities: We seek to invest a portion of our assets in secured first lien debt securities also known as senior loans, senior term loans, lines of credit and senior notes. Using its assets as collateral, the borrower typically uses secured first lien debt to cover a substantial portion of the funding needs of the business. These debt securities usually take the form of first priority liens on all, or substantially all, of the assets of the business. •Secured Second Lien Debt Securities: We seek to invest a portion of our assets in secured second lien debt securities, which may also be referred to as subordinated loans, subordinated notes and mezzanine loans. These secured second lien debt securities rank junior to the borrower’s secured first lien debt securities and may be secured by second priority liens on all or a portion of the assets of the business. Additionally, we may receive other yield enhancements in addition to or in lieu of success fees, such as warrants to buy common and preferred stock or limited liability interests, in connection with these secured second lien debt securities. •Preferred and Common Equity/Equivalents: We seek to invest a portion of our assets in equity securities, which consist of preferred and common equity, limited liability company interests, warrants or options to acquire such securities, and are generally in combination with our debt investment in a business. Additionally, we may receive equity investments derived from restructurings on some of our existing debt investments. In many cases, we will own a significant portion of the equity of the businesses in which we invest. We expect that most, if not all, of the debt securities we acquire will not be rated by a rating agency. Investors should assume that these loans would be rated below what is considered “investment grade” quality. Investments rated below investment grade are often referred to as high yield securities or junk bonds and may be considered higher risk as compared to investment grade debt instruments. |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | RISK FACTORS You should carefully consider these risk factors, together with all of the other information included in this Annual Report and the other reports and documents filed by us with the SEC. The risks set out below are not the only risks we face. Additional risks and uncertainties not presently known to us, or not presently deemed material by us, may also impair our operations and performance. If any of the following events occur, our business, financial condition, results of operations and cash flows could be materially and adversely affected. If that happens, the trading price of our securities and the NAV of our common stock could decline, and you may lose all or part of your investment. The risk factors described below are the principal risk factors associated with an investment in our securities as well as those factors generally associated with an investment company with investment objectives, investment policies, capital structure or trading markets similar to ours. |  |  |  |  |  |  |  |  |  |
Effects of Leverage [Text Block] |  |  |  |  |  |  |  |  |  | We financed certain of our investments with borrowed money and capital from the issuance of senior securities, which will magnify the potential for gain or loss on amounts invested and may increase the risk of investing in us. |  |  |  |  |  |  |  |  |  |
Annual Interest Rate [Percent] |  |  |  |  |  |  |  |  |  | 6.20% |  |  |  |  |  |  |  |  |  |
Annual Coverage Return Rate [Percent] |  |  |  |  |  |  |  |  |  | 3.00% |  |  |  |  |  |  |  |  |  |
Effects of Leverage [Table Text Block] |  |  |  |  |  |  |  |  |  | The following table illustrates the effect of leverage on returns from an investment in our common stock assuming various annual returns on our portfolio, net of expenses. The calculations in the table below are hypothetical and actual returns may be higher or lower than those appearing in the table below.
| Assumed Return on Our Portfolio (Net of Expenses)
| (10)% | (5)% | 0% | 5% | 10%
Corresponding return to common stockholder(A) | (25.96)% | (15.87)% | (5.79)% | 4.29% | 14.37%
(A)The hypothetical return to common stockholders is calculated by multiplying our total assets as of March 31, 2025 by the assumed rates of return and subtracting all interest on our debt expected to be paid during the twelve months following March 31, 2025, and then dividing the resulting difference by our total net assets attributable to common stock as of March 31, 2025. Based on $1.0 billion in total assets, no borrowings outstanding on our Credit Facility, $127.9 million of 5.00% 2026 Notes, at cost, $134.6 million of 4.875% 2028 Notes, at cost, $74.8 million of 8.00% 2028 Notes, at cost, $126.5 million of 7.875% 2030 Notes, at cost, and $499.1 million in net assets as of March 31, 2025. |  |  |  |  |  |  |  |  |  |
Return at Minus Ten [Percent] |  |  |  |  |  |  |  |  |  | (25.96%) |  |  |  |  |  |  |  |  |  |
Return at Minus Five [Percent] |  |  |  |  |  |  |  |  |  | (15.87%) |  |  |  |  |  |  |  |  |  |
Return at Zero [Percent] |  |  |  |  |  |  |  |  |  | (5.79%) |  |  |  |  |  |  |  |  |  |
Return at Plus Five [Percent] |  |  |  |  |  |  |  |  |  | 4.29% |  |  |  |  |  |  |  |  |  |
Return at Plus Ten [Percent] |  |  |  |  |  |  |  |  |  | 14.37% |  |  |  |  |  |  |  |  |  |
Effects of Leverage, Purpose [Text Block] |  |  |  |  |  |  |  |  |  | The use of leverage, including through the issuance of senior securities that are debt or stock, magnifies the potential for gain or loss on amounts invested and, if we incur additional leverage, this potential will be further magnified. We have incurred leverage in the past and currently incur leverage through the Credit Facility, the 5.00% 2026 Notes, the 4.875% 2028 Notes, the 8.00% 2028 Notes and 7.875% 2030 Notes and, from time to time, may incur additional leverage to the extent permitted under the 1940 Act. The use of leverage is generally considered a speculative investment technique and increases the risks associated with investing in our securities. In the future, we may borrow from, and issue senior securities to, banks and other lenders. Holders of these senior securities will have fixed dollar claims on our assets that are superior to the claims of our common stockholders, and we would expect such holders to seek recovery against our assets in the event of a default. |  |  |  |  |  |  |  |  |  |
Share Price [Table Text Block] |  |  |  |  |  |  |  |  |  | Our common stock is traded on Nasdaq under the symbol “GAIN.” The following table reflects, by quarter, the high and low intraday sales prices per share of our common stock on Nasdaq, the intraday sales prices as a percentage of NAV per share and quarterly distributions declared per common share for each fiscal quarter during the last two completed fiscal years and the current fiscal year through May 12, 2025.
Quarter Ended/Ending |  | NAV(A) |  | Sales Prices |  | Premium / (Discount) of High to NAV(B) |  | Premium (Discount) of Low to NAV(B) |  | Declared Common Stock Distributions |
|  | High |  | Low |  |  |
Fiscal Year ended March 31, 2024: |  |  |  |  |  |  |  |  |  |  |  |  |
6/30/2023 |  | $ | 12.99 |  |  | $ | 13.91 |  |  | $ | 12.53 |  |  | 7 | % |  | (4) | % |  | $ | 0.3600 |  | (C)
9/30/2023 |  | $ | 14.03 |  |  | $ | 13.88 |  |  | $ | 12.44 |  |  | (1) | % |  | (11) | % |  | $ | 0.3600 |  | (C)
12/31/2023 |  | $ | 13.01 |  |  | $ | 14.92 |  |  | $ | 12.14 |  |  | 15 | % |  | (7) | % |  | $ | 1.2400 |  | (C)
3/31/2024 |  | $ | 13.43 |  |  | $ | 14.96 |  |  | $ | 13.30 |  |  | 11 | % |  | (1) | % |  | $ | 0.2400 |  |
Fiscal Year ended March 31, 2025: |  |  |  |  |  |  |  |  |  |  |  |  |
6/30/2024 |  | $ | 13.01 |  |  | $ | 14.55 |  |  | $ | 13.66 |  |  | 12 | % |  | 5 | % |  | $ | 0.2400 |  |
9/30/2024 |  | $ | 12.49 |  |  | $ | 14.58 |  |  | $ | 12.46 |  |  | 17 | % |  | — | % |  | $ | 0.2400 |  |
12/31/2024 |  | $ | 13.30 |  |  | $ | 14.85 |  |  | $ | 12.81 |  |  | 12 | % |  | (4) | % |  | $ | 0.9400 |  | (D)
3/31/2025 |  | $ | 13.55 |  |  | $ | 14.01 |  |  | $ | 12.54 |  |  | 3 | % |  | (7) | % |  | $ | 0.2400 |  |
Fiscal Year ending March 31, 2026: |  |  |  |  |  |  |  |  |  |  |  |  |
6/30/2025 (through May 12, 2025) |  | * |  | $ | 14.11 |  |  | $ | 11.42 |  |  | * |  | * |  | $ | 0.7800 |  | (E)
(A)NAV per share is determined as of the last day in the relevant quarter and therefore may not reflect the NAV per share on the date of the high and low intraday sales prices. The NAVs per share shown are based on outstanding shares at the end of each period. (B)The premiums (discounts) set forth in these columns represent the high or low, as applicable, intraday sale prices per share for the relevant quarter minus the NAV per share as of the end of such quarter, and therefore may not reflect the premium (discount) to NAV per share on the date of the high and low intraday sales prices. (C)Includes $0.12, $0.12, $0.12 and $0.88 per common share supplemental distributions paid in June 2023, September 2023, November 2023 and December 2023, respectively. (D)Includes a $0.70 per common share supplemental distribution paid in October 2024. (E)Includes a $0.54 per common share supplemental distribution to be paid in June 2025. * Not yet available, as the NAV per share as of the end of this quarter has not yet been finalized. |  |  |  |  |  |  |  |  |  |
Lowest Price or Bid | $ 11.42 | $ 12.54 | $ 12.81 | $ 12.46 | $ 13.66 | $ 13.30 | $ 12.14 | $ 12.44 | $ 12.53 |  |  |  |  |  |  |  |  |  |  |
Highest Price or Bid | $ 14.11 | $ 14.01 | $ 14.85 | $ 14.58 | $ 14.55 | $ 14.96 | $ 14.92 | $ 13.88 | $ 13.91 |  |  |  |  |  |  |  |  |  |  |
Highest Price or Bid, Premium (Discount) to NAV [Percent] |  | 3.00% | 12.00% | 17.00% | 12.00% | 11.00% | 15.00% | (1.00%) | 7.00% |  |  |  |  |  |  |  |  |  |  |
Lowest Price or Bid, Premium (Discount) to NAV [Percent] |  | (7.00%) | (4.00%) | 0.00% | 5.00% | (1.00%) | (7.00%) | (11.00%) | (4.00%) |  |  |  |  |  |  |  |  |  |  |
Share Price |  | $ 13.36 |  |  |  |  |  |  |  | $ 13.36 |  |  |  |  |  |  |  |  |  |
NAV Per Share |  | $ 13.55 |  |  |  | $ 13.43 |  |  |  | $ 13.55 | $ 13.43 | $ 13.09 | $ 13.43 | $ 11.52 | $ 11.17 | $ 12.40 | $ 10.85 | $ 9.95 | $ 9.22 | $ 9.18
Latest Premium (Discount) to NAV [Percent] |  |  |  |  |  |  |  |  |  | (1.40%) |  |  |  |  |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt [Table Text Block] |  |  |  |  |  |  |  |  |  | Revolving Line of Credit As of March 31, 2025, our Credit Facility had a total commitment amount of $270.0 million with an “accordion” feature that permits us to increase the size of the facility to $300.0 million. The Credit Facility has a revolving period end date of October 30, 2026 and a final maturity date of October 30, 2028 (at which time all principal and interest will be due and payable if the Credit Facility is not extended by the revolving period end date). Advances under the Credit Facility generally bear interest at 30-day Term SOFR, subject to a floor of 0.35%, with a SOFR credit spread adjustment of 10 basis points, plus a margin of 3.15% per annum until October 30, 2026, with the margin then increasing to 3.40% for the period from October 30, 2026 to October 30, 2027, and increasing further to 3.65% thereafter. The Credit Facility has an unused commitment fee on the daily unused commitment amount of 0.50% per annum if the daily unused commitment amount is less than or equal to 50% of the total commitment amount, 0.75% per annum if the daily unused commitment amount is greater than 50% but less than or equal to 65% of the total commitment amount, and 1.00% per annum if the daily unused commitment amount is greater than 65% of the total commitment amount. At March 31, 2025, we had no borrowings outstanding on our Credit Facility and as of the date of this report, we had $56.0 million outstanding under our Credit Facility. Interest is payable monthly during the term of our Credit Facility. Available borrowings are subject to various constraints and applicable advance rates, which are generally based on the size, characteristics, and quality of the collateral pledged by Business Investment. Our Credit Facility also requires that any interest and principal payments on pledged loans be remitted directly by the borrower into a lockbox account with KeyBank. KeyBank is also the trustee of the account and generally remits the collected funds to us once a month. Among other things, our Credit Facility contains covenants that require Business Investment to maintain its status as a separate legal entity, prohibit certain significant corporate transactions (such as mergers, consolidations, liquidations or dissolutions) and restrict certain material changes to our credit and collection policies without the lenders’ consent. Our Credit Facility also generally seeks to restrict distributions to stockholders to the sum of (i) our net investment income, (ii) net capital gains, and (iii) amounts deemed by the Company to be considered as having been paid during the prior fiscal year in accordance with Section 855(a) of the Code. Loans eligible to be pledged as collateral are subject to certain limitations, including, among other things, restrictions on geographic concentrations, industry concentrations, loan size, payment frequency and status, average life, portfolio company leverage, and lien property. Our Credit Facility also requires Business Investment to comply with other financial and operational covenants, which obligate Business Investment to, among other things, maintain certain financial ratios, including asset and interest coverage and a minimum number of obligors required in the borrowing base. Additionally, our Credit Facility contains a performance guaranty that requires the Company to maintain (i) a minimum net worth (defined in our Credit Facility to include any outstanding mandatorily redeemable preferred stock) of the greater of $210.0 million or $210.0 million plus 50% of all equity and subordinated debt raised minus 50% of any equity or subordinated debt redeemed or retired after November 16, 2016, which equated to $412.9 million as of March 31, 2025, (ii) asset coverage with respect to senior securities representing indebtedness of at least 150% (or such percentage as may be set forth in Section 18 of the 1940 Act, as modified by Section 61 of the 1940 Act); and (iii) our status as a BDC under the 1940 Act and as a RIC under the Code. As of March 31, 2025, and as defined in the performance guaranty of our Credit Facility, we had a net worth of $953.3 million, asset coverage on our senior securities representing indebtedness of 204.4%, calculated in compliance with the requirements of Sections 18 and 61 of the 1940 Act, and an active status as a BDC and RIC. As of March 31, 2025, we had availability, after adjustments for various constraints based on collateral quality, of $270.0 million under our Credit Facility and were in compliance with all covenants under our Credit Facility. Notes Payable 5.00% Notes due 2026 In March 2021, we completed a public offering of the 5.00% 2026 Notes with an aggregate principal amount of $127.9 million, which resulted in net proceeds of approximately $123.8 million after deducting underwriting discounts, commissions and offering costs borne by us. The 5.00% 2026 Notes are traded under the ticker symbol “GAINN” on Nasdaq. The 5.00% 2026 Notes will mature on May 1, 2026 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 5.00% 2026 Notes bear interest at a rate of 5.00% per year (which equates to $6.4 million per year), payable quarterly in arrears. The indenture relating to the 5.00% 2026 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 5.00% 2026 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. The 5.00% 2026 Notes are recorded at the aggregate principal amount, less underwriting discounts, commissions, and offering costs, on our accompanying Consolidated Statements of Assets and Liabilities. Total underwriting discounts, commissions, and offering costs related to this offering were $4.1 million, which have been recorded as discounts to the aggregate principal amount on our accompanying Consolidated Statements of Assets and Liabilities and are being amortized over the period ending May 1, 2026, the maturity date. |  |  |  |  |  |  |  |  |  |
Risks Related to the Economy [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to the Economy Market conditions could negatively impact our business, results of operations, financial condition, and cash flows. The market in which we operate is affected by a number of factors that are largely beyond our control but can nonetheless have a potentially significant, negative impact on us. These factors include, among other things: •changes in interest rates and credit spreads and the effects of inflation on us and our portfolio companies; •the availability of credit, including the price, terms and conditions under which it can be obtained; •the quality, pricing, and availability of suitable investments and credit losses with respect to our investments; •the ability to obtain accurate market-based valuations; •investment values relative to the value of the underlying assets; •default rates on the loans underlying our investments and the amount of related losses; •prepayment rates, delinquency rates and the timing and amount of servicer advances; •competition; •the actual and perceived state of the economy and capital markets generally; •amendments or repeals of legislation, or changes in regulations or regulatory interpretations thereof, and transitions of government, including uncertainty regarding any of the foregoing; •the national and global political environment, including war, armed conflicts, foreign relations and trading policies; •the impact of potential changes to the Code; and •the attractiveness of other types of investments relative to investments in Lower Middle Market companies generally. Changes in these factors are difficult to predict, and a change in one factor could affect other factors, which could result in adverse effects to our business, results of operations, financial condition, and cash flows. Volatility in the capital markets could make it more difficult to raise capital and may adversely affect the valuations of our investments. Given the volatility and dislocation that the capital markets have experienced from time to time, many BDCs have faced, and may in the future face, a challenging environment in which to raise capital. We may in the future have difficulty accessing debt and equity capital, and a severe disruption in U.S. or global financial markets or deterioration in credit and financing conditions could have a material adverse effect on our business, financial condition, results of operations, and cash flows. In addition, significant changes in the capital markets have had, and may in the future have, a negative effect on the valuations of our investments and on the potential for liquidity events involving our investments. An inability to raise capital, and any required sale of our investments for liquidity purposes, could have a material adverse impact on our business, financial condition, results of operations, or cash flows. Tariffs may adversely affect us or our portfolio companies. Existing or new tariffs imposed on foreign goods imported by the United States or on U.S. goods imported by foreign countries could subject us or our portfolio companies to additional risks. Among other effects, tariffs could increase the cost of production for certain of our portfolio companies or reduce demand for their products, which could affect their results of operations. We cannot predict whether, or to what extent, any tariff or other trade protections may affect us or our portfolio companies. We may experience fluctuations in our quarterly and annual results based on the impact of inflation in the U.S. Certain of our portfolio companies are in industries that have been and, in the future, may be impacted by inflation, such as consumer goods and services and manufacturing. Our portfolio companies may not be able to pass on to customers increases in their costs of operations which could greatly affect their operating results, impacting their ability to repay our loans. In addition, any projected future decreases in our portfolio companies’ operating results due to inflation could adversely impact the fair value of those investments. Any decreases in the fair value of our investments could result in future unrealized losses and therefore reduce our net assets resulting from operations. |  |  |  |  |  |  |  |  |  |
Risks Related to Interest Rates [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to Interest Rates Market interest rates may have an effect on the value of our securities. One of the factors that influences the price of our securities is the distribution yield on our securities (as a percentage of the price of our securities) relative to market interest rates. An increase in market interest rates may lead prospective purchasers of our securities to expect a higher distribution yield. In addition, higher interest rates have increased our borrowing costs. As a result, higher market interest rates could to cause the market price of our securities to decrease. Changes in interest rates may negatively impact our investments and have an adverse effect on our business, financial condition, results of operations, and cash flows. Generally, interest rate fluctuations and changes in credit spreads on floating rate loans may have a negative impact on our investments and investment opportunities and, accordingly, may have a material adverse effect on our rate of return on invested capital, our net investment income, our NAV and the market price of our securities. As interest rates increase, generally, the cost of borrowing under our Credit Facility increases, which may affect our ability to make new investments on favorable terms or at all. A substantial portion of our debt investments have variable interest rates that reset periodically and are generally based on SOFR. If interest rates increase, the operating performance of certain of our portfolio companies may be affected by increasing debt service obligations and, therefore, may affect our results of operations. In addition, to the extent that increases in interest rates make it difficult or impossible to make payments on outstanding indebtedness to us or other financial sponsors or refinance debt that is maturing in the near term, some of our portfolio companies may be unable to repay such debt at maturity and may be forced to sell assets, undergo a recapitalization or seek bankruptcy protection. Elevated interest rates could also cause borrowers to shift cash from other productive uses to the payment of interest, which may have a material adverse effect on their business and operations and could, over time, lead to increased defaults. Additionally, as interest rates increase and the corresponding risk of a default by borrowers increases, the liquidity of higher interest rate loans may decrease as fewer investors may be willing to purchase such loans in the secondary market in light of the increased risk of a default by the borrower and the heightened risk of a loss of an investment in such loans. Decreases in credit spreads on debt that pays a floating rate of return would have an impact on the income generation of our floating rate assets. Trading prices for debt that pays a fixed rate of return tend to fall as interest rates rise. Trading prices tend to fluctuate more for fixed rate securities that have longer maturities. If interest rates remain elevated or rise again in the future, it could have a negative effect on our investments, which could negatively impact our operating results, financial condition, and cash flows. Conversely, reduced interest rates, including recent rate decreases, will result in a decrease in our total investment income unless offset by interest rate floors or an increase in the spread of our debt investments with variable interest rates. In addition, our net investment income could decrease if there is no reduction or credit to the base management or incentive fees that we pay to the Adviser or if we are unable to refinance our fixed rate debt obligations or issue new fixed rate debt at lower rates. In addition, when interest rates decline, borrowers may refinance their loans at lower interest rates, which could shorten the average life of the loans and reduce the associated returns on the investment, as well as require the Adviser and its investment professionals to incur management time and expense to re-deploy such proceeds, including on terms that may not be as favorable as our existing loans. A change in interest rates may adversely affect our profitability and any hedging strategy may expose us to additional risks. We use combination of equity and long-term and short-term borrowings to finance our investment activities. As a result, a portion of our income depends upon the spread between the rate at which we borrow funds and the rate at which we loan these funds. An increase or decrease in interest rates could reduce the spread between the rate at which we invest and the rate at which we borrow, and thus, adversely affect our profitability if we have not appropriately hedged against such event. Alternatively, interest rate hedging arrangements may limit our ability to participate in the benefits of lower interest rates with respect to the hedged portfolio. Ultimately, we expect approximately 90% of the loans in our portfolio to be at variable rates determined on the basis of the SOFR and approximately up to 10% to be at fixed rates. As of March 31, 2025, based on the total principal balance of debt investments outstanding, our portfolio consisted of 100.0% of loans at variable rates with floors. As of March 31, 2025, we did not have any hedging arrangements, such as interest rate hedges, in place. While hedging arrangements may insulate us against adverse fluctuations in interest rates, they may also limit our ability to participate in the benefits of lower interest rates with respect to the hedged portfolio. Adverse developments resulting from changes in interest rates or any future hedging transactions could have a material adverse effect on our business, financial condition, results of operations, and cash flows. Our ability to receive payments pursuant to a hedging arrangement is linked to the ability of the counter-party to that hedging arrangement to make the required payments. To the extent that the counter-party to the hedging arrangement is unable to pay pursuant to the terms of the agreement, we may lose the hedging protection of the arrangement. Also, the fair value of certain of our debt investments is based, in part, on the current market yields or interest rates of similar securities. A change in interest rates could have a significant impact on our determination of the fair value of these debt investments. In addition, a change in interest rates could also have an impact on the fair value of any hedging arrangements then in effect that could result in the recording of unrealized appreciation or depreciation in future periods. Therefore, adverse developments resulting from changes in interest rates could have a material adverse effect on our business, financial condition, results of operations, and cash flows. Refer to “Quantitative and Qualitative Disclosures About Market Risk” for additional information on interest rate fluctuations. |  |  |  |  |  |  |  |  |  |
Risks Related to Our Investments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to Our Investments We operate in a highly competitive market for investment opportunities. There is competitive pressure in the BDC and investment company marketplace for first and second lien secured debt, which can result in reduced yields on investment. A large number of entities compete with us to make the types of investments we seek to make in Lower Middle Market companies. We compete with public and private buyout funds, commercial and investment banks, commercial financing companies, and, to the extent that they provide an alternative form of financing, hedge funds, mutual funds, and private equity. Many of our competitors are substantially larger and have considerably greater financial, technical and marketing resources than we do. For example, some competitors may have a lower cost of funds and access to funding sources that are not available to us. In addition, some of our competitors may have higher risk tolerances or different risk assessments, which would allow them to consider a wider variety of investments and establish more relationships than us. Furthermore, many of our competitors are not subject to the regulatory restrictions that the 1940 Act imposes on us as a BDC. The competitive pressures we face could have a material adverse effect on our business, financial condition and results of operations. Also, as a result of this competition, we may not be able to take advantage of attractive investment opportunities from time to time and we can offer no assurance that we will be able to identify and make investments that are consistent with our investment objectives. We do not seek to compete based on the interest rates we offer, and we believe that some of our competitors may make loans with interest rates that will be comparable to or lower than the rates we offer. We may lose investment opportunities if we do not match our competitors’ pricing, terms, and structure. However, if we match our competitors’ pricing, terms, and structure, we may experience decreased net interest income and increased risk of credit loss. Our investments in Lower Middle Market portfolio companies are extremely risky and could cause you to lose all or a part of your investment. Investments in Lower Middle Market portfolio companies are subject to a number of significant risks including the following: •Lower Middle Market businesses are likely to have greater exposure to economic downturns than larger businesses. Our portfolio companies may have fewer resources than larger businesses, and any economic downturns or recessions are more likely to have a material adverse effect on them. When the economy contracts, the financial results of Lower Middle Market businesses, like those in which we invest, could experience deterioration or limited growth from current levels, which could ultimately lead to difficulty in meeting their debt service requirements and an increase in defaults. Consequently, for any portfolio company that is adversely impacted by an economic downturn or recession, its ability to repay our loan(s) or engage in a liquidity event, such as a sale, recapitalization or initial public offering would be diminished. •Lower Middle Market businesses may have limited financial resources and may not be able to repay the loans we make to them. Our strategy includes providing financing to portfolio companies that typically do not have readily available access to financing. While we believe that this provides an attractive opportunity for us to generate profits, this may make it difficult for the portfolio companies to repay their loans to us upon maturity. A borrower’s ability to repay its loan(s) may be adversely affected by numerous factors, including the failure to meet its business plan, a downturn in its industry or negative economic conditions. Deterioration in a borrower’s financial condition and prospects usually will be accompanied by deterioration in the value of any collateral and a reduction in the likelihood of realizing on any guaranties we may have obtained from the borrower’s management. As of March 31, 2025, loans to four portfolio companies were on non-accrual status with an aggregate debt cost basis of $90.2 million, or 13.1% of the cost basis of all debt investments in our portfolio. We cannot assure you that our efforts to improve profitability and cash flows of these companies will prove successful. In some of our loans we expect to be subordinated to a senior lender and our security interest in any collateral would, accordingly, likely be second lien and subordinate to another lender’s security interest. •Lower Middle Market businesses typically have narrower product lines and smaller market shares than large businesses. Our target portfolio companies tend to be more vulnerable to competitors’ actions and market conditions, as well as general economic downturns. In addition, our portfolio companies may face intense competition, including competition from companies with greater financial resources, more extensive development, manufacturing, marketing and other capabilities and a larger number of qualified managerial and technical personnel. •There is generally little or no publicly available information about these businesses. Because we seek to invest in privately owned businesses, there is generally little or no publicly available operating and financial information about our potential portfolio companies. As a result, we rely on our officers, the Adviser and its employees, Gladstone Securities and consultants to perform due diligence investigations of these portfolio companies, their operations, and their prospects. We may not learn all of the material information we need to know regarding these businesses through our investigations to make a well-informed investment decision. •Lower Middle Market businesses generally have less predictable operating results. We expect that our portfolio companies may have significant variations in their operating results, may from time to time be exposed to litigation, may be engaged in rapidly changing businesses with products subject to a substantial risk of obsolescence, may require substantial additional capital to support their operations, to finance expansion or to maintain their competitive position, may otherwise have a weak financial position or may be adversely affected by changes in the business cycle. Our portfolio companies may not meet net income, cash flow and other coverage tests typically imposed by their senior lenders. A borrower’s failure to satisfy financial or operating covenants imposed by senior lenders could lead to defaults and, potentially, foreclosure on its senior credit facility, which could additionally trigger cross-defaults in other agreements. If this were to occur, it is possible that the borrower’s ability to repay our loan(s) would be jeopardized. •Lower Middle Market businesses are more likely to be dependent on one or two persons. Typically, the success of a Lower Middle Market business also depends on the management talents and efforts of one or two persons or a small group of persons. The death, disability or resignation of one or more of these persons could have a material adverse impact on our portfolio company and, in turn, on us. •Lower Middle Market businesses may have limited operating histories. While we intend to continue to target stable companies with proven track records, we may invest in new companies that meet our other investment criteria. Portfolio companies with limited operating histories will be exposed to all of the operating risks that new businesses face and may be particularly susceptible to, among other risks, market downturns, competitive pressures and the departure of key executive officers. •Debt securities of Lower Middle Market companies typically are not rated by a credit rating agency. Typically, a Lower Middle Market business cannot or will not expend the resources to have their debt securities rated by a credit rating agency. We expect that most, if not all, of the debt securities we acquire will be unrated. Investors should assume that these loans would be at rates below what is considered “investment grade” quality. Investments rated below investment grade are often referred to as high yield securities or junk bonds and may be considered high risk as compared to investment grade debt instruments. •Lower Middle Market companies may be highly leveraged. Some of our portfolio companies are highly leveraged, which could have adverse consequences to these companies and to us as an investor. These companies may be subject to restrictive financial and operating covenants and the leverage could impair these companies’ ability to finance their future operations and capital needs. As a result, these companies’ flexibility to respond to changing business and economic conditions and to take advantage of business opportunities may be limited. Further, a leveraged company’s income and net assets will tend to increase or decrease at a greater rate than if borrowed money were not used. •Lower Middle Market companies may operate in regulated industries or provide services to governments. Some of our portfolio companies may operate in regulated industries and/or provide services to federal, state or local governments, or operate in industries that provide services to regulated industries or federal, state or local governments, any of which could lead to delayed payments for services or subject the company to changing payment and reimbursement rates or other terms. Because the majority of the loans we make and equity securities we invest in are not publicly traded, there is uncertainty regarding the value of our privately-held securities. Substantially all of our portfolio investments are, and we expect will continue to be, in the form of securities that are not publicly traded. The fair value of securities and other investments that are not publicly traded may not be readily determinable. In valuing our investment portfolio, several techniques are used, including, a total enterprise value approach, a yield analysis, and market quotes. A third-party valuation firm provides estimates of fair value on generally all of our debt investments that are not valued using total enterprise value (“TEV”) and we use another independent valuation firm to provide valuation inputs for our significant equity investments, which are generally valued using TEV, including earnings multiple ranges, as well as other information. In addition to these techniques, inputs and information, other factors are considered when determining fair value of our investments, including: the nature and realizable value of the collateral, including external parties’ guaranties; any relevant offers or letters of intent to acquire the portfolio company; timing of expected loan repayments; and the markets in which the portfolio company operates. Fair value measurements of our investments may involve subjective judgments and estimates and, due to the uncertainty inherent in valuing these securities, the determination of fair value may fluctuate from period to period and may differ materially from the values that could be obtained if a ready market for these securities existed. Additionally, changes in the market environment and other events that may occur over the life of the investment may cause the gains or losses ultimately realized on these investments to be different than the valuations currently assigned. Our NAV would be adversely affected if the fair value of our investments are higher than the values that we ultimately realize upon the disposal of such securities. The valuation process for certain of our portfolio holdings creates a conflict of interest. A substantial portion of our portfolio investments are securities for which market quotations are not readily available. In connection with the determination of the fair value of these securities, our Valuation Team prepares portfolio company valuations based upon the most recent portfolio company financial statements available and projected financial results of each portfolio company. The participation of our Adviser’s investment professionals in our valuation process and Mr. Gladstone’s pecuniary interest in our Adviser may result in a conflict of interest, as the management fees that we pay our Adviser are based on our average gross assets, less uninvested cash or cash equivalents from borrowings, and adjusted appropriately for any share issuances or repurchases during the period. The lack of liquidity of our privately-held investments may adversely affect our business. We generally make investments in private companies whose securities are not traded in any public market. Substantially all of the investments we presently hold and the investments we expect to acquire in the future are, and will be, subject to legal and other restrictions on resale and will otherwise be less liquid than publicly-traded securities. The illiquidity of our investments may make it difficult for us to quickly obtain cash equal to the value at which we record our investments if the need arises. This could cause us to miss important investment opportunities. In addition, if we are required to liquidate all or a portion of our portfolio quickly, we may record substantial realized losses upon liquidation. We may also face other restrictions on our ability to liquidate an investment in a portfolio company to the extent that we, the Adviser, the Administrator, or our respective officers, or affiliates have material non-public information regarding such portfolio company. Due to the uncertainty inherent in valuing these securities, the Adviser’s determinations of fair value may differ materially from the values that could be obtained if a ready market for these securities existed. Our NAV could be materially affected if the Adviser’s determinations regarding the fair value of our investments are materially different from the values that we ultimately realize upon our disposal of such securities. Our financial results could be negatively affected if a significant portfolio investment fails to perform as expected. Our total investment in one or more companies may be significant individually or in the aggregate. As a result, if a significant investment in one or more companies fails to perform as expected, our financial results could be more negatively affected and the magnitude of the loss could be more significant than if we had made smaller investments in more companies. Our five largest investments represented 41.0% and 42.7% of the fair value of our total portfolio as of March 31, 2025 and 2024, respectively. Any disposition of a significant investment in one or more portfolio companies may negatively impact our net investment income and limit our ability to pay distributions. We typically invest in transactions involving acquisitions, buyouts and recapitalizations of companies, which subjects us to the risks associated with change in control transactions. Our strategy, in part, includes making debt and equity investments in companies in connection with acquisitions, buyouts and recapitalizations, which subjects us to the risks associated with change in control transactions. Change in control transactions often present a number of uncertainties. Companies undergoing change in control transactions often face challenges retaining key employees and maintaining relationships with customers and suppliers. While we hope to avoid many of these difficulties by participating in transactions where the management team is retained and by conducting thorough due diligence in advance of our decision to invest, if our portfolio companies experience one or more of these problems, we may not realize the value that we expect in connection with our investments, which would likely harm our operating results, financial condition, and cash flows. Our portfolio companies may incur debt that ranks equally with, or senior to, our investments in such companies and/or we could be subject to lender liability claims. We primarily invest in secured first and second lien debt securities issued by our portfolio companies. In some cases, portfolio companies will be permitted to have other debt that ranks equally with, or senior to, the debt securities in which we invest. By their terms, such debt securities may provide that the holders thereof are entitled to receive payment of interest and principal on or before the dates on which we are entitled to receive payments in respect of the debt securities in which we invest. Also, in the event of insolvency, liquidation, dissolution, reorganization, or bankruptcy of a portfolio company, holders of debt instruments ranking senior to our investment in that portfolio company would typically be entitled to receive payment in full before we receive any distribution in respect of our investment. Additionally, depending on the facts and circumstances, including the extent to which we provide managerial assistance to any portfolio company subject to bankruptcy, a bankruptcy court might re-characterize our debt investments and subordinate all or a portion of our claims to that of other creditors. After repaying such senior creditors, such portfolio company may not have any remaining assets to use for repaying its obligation to us. We may also be subject to lender liability claims for actions taken by us with respect to a borrower’s business or in instances in which we exercised control over the borrower as a result of actions taken in rendering any managerial assistance. Furthermore, in the case of debt ranking equally with debt securities in which we invest, we would have to share on an equal basis any distributions with other creditors holding such debt in the event of an insolvency, liquidation, dissolution, reorganization, or bankruptcy of a portfolio company. Our portfolio is concentrated in a limited number of companies and industries, which subjects us to an increased risk of significant loss if any one of these companies does not repay us or if the industries experience downturns. As of March 31, 2025, we had investments in 25 portfolio companies, the five largest of which included SFEG, Ricardo, Brunswick, Nielsen-Kellerman and E3 and comprised $401.7 million, or 41.0%, of our total investment portfolio, at fair value. A consequence of a limited number of investments is that the aggregate returns we realize may be substantially adversely affected by the unfavorable performance of a small number of such investments or a substantial write-down of any one investment. Beyond our regulatory and income tax diversification requirements, as well as Credit Facility requirements, we do not have fixed guidelines for industry concentration and our investments could potentially be concentrated in relatively few industries. In addition, while we do not intend to invest 25% or more of our total assets in a particular industry or group of industries at the time of investment, it is possible that as the values of our portfolio companies change, one industry or a group of industries may comprise in excess of 25% of the value of our total assets. A downturn in a particular industry in which we have invested a significant portion of our total assets could have a materially adverse effect on us. As of March 31, 2025, our largest industry concentration was in Diversified/Conglomerate Services, representing 17.4% of our total investments, at fair value. Volatility of oil and natural gas prices could impair certain of our portfolio companies’ operations and ability to satisfy obligations to their respective lenders and investors, including us, which could negatively impact our financial condition. Our portfolio includes companies related to the oil and gas industry with the fair value of these investments representing approximately $69.6 million, or 7.1% of our total portfolio at fair value, as of March 31, 2025. These businesses provide services to oil and gas companies and are indirectly impacted by the prices of, and demand for, oil and natural gas, which have from time to time experienced volatility, including rapid and significant changes in prices, and such volatility could continue or increase in the future. A substantial decline in oil and natural gas demand or prices may adversely affect the business, financial condition, cash flows, liquidity or results of operations of these portfolio companies and might impair their ability to meet capital expenditure obligations and financial commitments. Any decline in oil prices, especially for a prolonged period, could therefore have a material adverse effect on our business, financial condition and results of operations. Our investments are typically long-term and will require several years to realize liquidation events. Since we generally make five year term loans and hold our loans and equity positions until the loans mature and/or we exit the investment, investors should not expect realization events, if any, to occur over the near term. In addition, we expect that any equity investments may require several years to appreciate in value and we cannot give any assurance that such appreciation will occur or ultimately be realized. The disposition of our investments may result in contingent liabilities. Currently, all but one of our investments involve private securities. In connection with the disposition of an investment in private securities, we may be required to make representations about the business and financial affairs of the underlying portfolio company typical of those made in connection with the sale of a business. We may also be required to indemnify the purchasers of such investment to the extent that any such representations turn out to be inaccurate or with respect to certain potential liabilities. These arrangements may result in contingent liabilities that may ultimately yield funding obligations that must be satisfied through our return of certain distributions previously made to us. Portfolio company litigation or other litigation or claims against us or our personnel could result in additional costs and the diversion of management time and resources. In the course of investing in and often providing significant managerial assistance to certain of our portfolio companies, certain persons employed by the Adviser sometimes serve as directors on the boards of such companies. To the extent that litigation arises out of our investments in these companies or otherwise, even if meritless, we or such employees may be named as defendants in such litigation, which could result in additional costs, including defense costs, and the diversion of management time and resources. We may be unable to accurately estimate our exposure to litigation risk if we record balance sheet reserves for probable loss contingencies. As a result, any reserves we establish to cover any settlements or judgments may not be sufficient to cover our actual financial exposure, which may have a material impact on our results of operations, financial condition, or cash flows. While we believe we would have valid defenses to potential claims brought due to our investment in any portfolio company, and will defend any such claims vigorously, we may nevertheless expend significant amounts of money in defense costs and expenses. Further, if we enter into settlements or suffer an adverse outcome in any litigation, we could be required to pay significant amounts. In addition, if any of our portfolio companies become subject to direct or indirect claims or other obligations, such as defense costs or damages in litigation or settlement, our investment in such companies could diminish in value and we could suffer indirect losses. Further, these matters could cause us to expend significant management time and effort in connection with assessment and defense of any claims. Any unrealized depreciation we experience on our investment portfolio may be an indication of future realized losses, which could reduce any gains available for distribution. As a BDC, we are required to carry our investments at market value or, if no market value is ascertainable, at fair value. We will record decreases in the market values or fair values of our investments as unrealized depreciation. Since our inception, we have, at times, incurred a cumulative net unrealized depreciation of our portfolio. Any unrealized depreciation in our investment portfolio could result in realized losses in the future and ultimately in reductions of any gains available for distribution to stockholders in future periods. |  |  |  |  |  |  |  |  |  |
Risks Related to Our External Financing [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to Our External Financing In addition to regulatory limitations on our ability to raise capital, our Credit Facility contains various covenants which, if not complied with, could accelerate our repayment obligations under the facility, thereby materially and adversely affecting our liquidity, financial condition, results of operations, cash flows, and ability to pay distributions. We will have a continuing need for capital to finance our investments. As of March 31, 2025, we, through our wholly-owned subsidiary, Business Investment, had no borrowings outstanding under our Credit Facility, which provides for maximum borrowings of $270.0 million, with a revolving period end date of October 30, 2026 (the “Revolving Period End Date”). Our Credit Facility permits us to fund additional loans and investments as long as we are within the conditions and covenants set forth in the credit agreement. Among other things, our Credit Facility contains covenants that require Business Investment to maintain its status as a separate legal entity, prohibit certain significant corporate transactions (such as mergers, consolidations, liquidations or dissolutions) and restrict certain material changes to our credit and collection policy without the lenders’ consent. Our Credit Facility also generally seeks to restrict distributions to stockholders to the sum of (i) our net investment income, (ii) net capital gains, and (iii) amounts deemed by the Company to be considered as having been paid during the prior fiscal year in accordance with Section 855(a) of the Code. Loans eligible to be pledged as collateral are subject to certain limitations, including, among other things, restrictions on geographic concentrations, industry concentrations, loan size, payment frequency and status, average life, portfolio company leverage, and lien property. Our Credit Facility also requires Business Investment to comply with other financial and operational covenants, which obligate Business Investment to, among other things, maintain certain financial ratios, including asset and interest coverage and a minimum number of obligors in the borrowing base. Additionally, our Credit Facility contains a performance guarantee that requires the Company to maintain (i) a minimum net worth of the greater of $210.0 million or $210.0 million plus 50% of all equity and subordinated debt raised minus 50% of any equity or subordinated debt redeemed or retired after November 16, 2016, which equated to $412.9 million as of March 31, 2025; (ii) asset coverage with respect to senior securities representing indebtedness of at least 150% (or such percentage as may be set forth in Section 18 of the 1940 Act, as modified by Section 61 of the 1940 Act); and (iii) our status as a BDC under the 1940 Act and as a RIC under the Code. As of March 31, 2025, and as defined in the performance guaranty of our Credit Facility, we had a net worth of $953.3 million, asset coverage on our senior securities representing indebtedness of 204.4%, calculated in accordance with the requirements of Sections 18 and 61 of the 1940 Act, and an active status as a BDC and RIC. As of March 31, 2025, we were in compliance with all covenants under our Credit Facility; however, our continued compliance depends on many factors, some of which are beyond our control. Any unrealized depreciation in our portfolio may increase in future periods and threaten our ability to comply with the minimum net worth covenant and other covenants under our Credit Facility. Our failure to satisfy these covenants could result in foreclosure by our lenders, which would accelerate our repayment obligations under the facility and thereby have a material adverse effect on our business, liquidity, financial condition, results of operations, cash flows, and ability to pay distributions to our stockholders. Any inability to renew, extend or replace our Credit Facility on terms favorable to us, or at all, could adversely impact our liquidity and ability to fund new investments or maintain distributions to our stockholders. If our Credit Facility is not renewed or extended by the Revolving Period End Date, all principal and interest will be due and payable on October 30, 2028 (two years after the Revolving Period End Date). Subject to certain terms and conditions, our Credit Facility may be expanded to a total of $300.0 million through additional commitments of existing or new lenders. However, if such lenders are unwilling to provide additional commitments under the terms of our Credit Facility, we will be unable to expand our Credit Facility and thus will continue to have limited availability to finance new investments under our Credit Facility. There can be no guaranty that we will be able to renew, extend or replace our Credit Facility upon its Revolving Period End Date on terms that are favorable to us, if at all. Our ability to expand our Credit Facility, and to obtain replacement financing at or before the time of its Revolving Period End Date, will be constrained by then current economic conditions affecting the credit markets. In the event that we are not able to expand our Credit Facility, or to renew, extend or refinance our Credit Facility by the Revolving Period End Date, this could have a material adverse effect on our liquidity and ability to fund new investments, our ability to make distributions to our stockholders and our ability to qualify as a RIC under the Code. If we are unable to secure replacement financing, we may be forced to sell certain assets on disadvantageous terms, which may result in realized losses, and such realized losses could materially exceed the amount of any unrealized depreciation on these assets as of our most recent balance sheet date, which would have a material adverse effect on our results of operations. In addition to selling assets, or as an alternative, we may issue common equity to repay amounts outstanding under our Credit Facility. Depending upon the trading prices of our common stock (and with the approval of our independent directors and stockholders), such an equity offering may have a dilutive impact on our existing stockholders’ interest in our earnings, assets and voting interest in us. If we are able to renew, extend or refinance our Credit Facility prior to maturity, renewal, extension or refinancing, it could potentially result in significantly higher interest rates and related charges and may impose significant restrictions on the use of borrowed funds to fund investments or maintain distributions to stockholders. Because we expect to distribute substantially all of our Investment Company Taxable Income, at least 90%, on an annual basis, our business plan is dependent upon external financing, which is constrained by the limitations of the 1940 Act. There can be no assurance that we will be able to raise capital through issuing equity in the near future. Our business requires a substantial amount of cash to operate and grow. We may acquire such additional capital from the following sources: •Senior Securities: We may issue "senior securities representing indebtedness" (including borrowings under our Credit Facility, our 5.00% 2026 Notes, our 4.875% 2028 Notes, our 8.00% 2028 Notes and our 7.875% 2030 Notes) and "senior securities that are stock", up to the maximum amount permitted by the 1940 Act. The 1940 Act currently permits us, as a BDC, to issue senior securities representing indebtedness and senior securities which are stock, in amounts such that our asset coverage, as defined in Section 18(h) of the 1940 Act, is at least 150% on each such senior security immediately after each issuance of each such senior security. As a result of issuing senior securities (in whatever form), we will be exposed to the risks associated with leverage. Although borrowing money for investments increases the potential for gain, it also increases the risk of a loss. A decrease in the value of our investments will have a greater impact on the value of our common stock to the extent that we have borrowed money to make investments. There is a possibility that the costs of borrowing could exceed the income we receive on the investments we make with such borrowed funds. In addition, our ability to pay distributions, issue senior securities or repurchase shares of our common stock would be restricted if the asset coverage on each of our senior securities is not at least 150%. If the aggregate fair value of our assets declines, we might be unable to satisfy that 150% requirement. To satisfy the 150% asset coverage requirement in the event that we are seeking to pay a distribution, we might either have to (i) liquidate a portion of our loan portfolio to repay a portion of our indebtedness or (ii) issue common stock. This may occur at a time when a sale of a portfolio asset may be disadvantageous, or when we have limited access to capital markets on agreeable terms. In addition, any amounts that we use to service our indebtedness, pay dividends on our preferred stock or for offering costs will not be available for distributions to common stockholders. Pursuant to Section 61(a)(3) of the 1940 Act, we are permitted, under specified conditions, to issue multiple classes of "senior securities representing indebtedness". However, pursuant to Section 18(c) of the 1940 Act, we are permitted to issue only one class of "senior securities that are stock". •Common and Convertible Preferred Stock: Because we are constrained in our ability to issue debt or senior securities for the reasons given above, we may at times be dependent on the issuance of equity as a financing source. If we raise additional funds by issuing more common stock, the percentage ownership of our common stockholders at the time of the issuance would decrease and our existing common stockholders may experience dilution. In addition, under the 1940 Act, we will generally not be able to issue additional shares of our common stock at a price below NAV per common share to purchasers, other than to our existing common stockholders through a rights offering, without first obtaining the approval of our stockholders and our independent directors. If we were to sell shares of our common stock below our then current NAV per common share, such sales would result in an immediate dilution to the NAV per common share. This dilution would occur as a result of the sale of common shares at a price below the then current NAV per share of our common stock and a proportionately greater decrease in a common stockholder’s interest in our earnings and assets and voting percentage than the increase in our assets resulting from such issuance. For example, if we issue and sell an additional 10% of our common stock at a 5% discount from NAV, a common stockholder who does not participate in that offering for its proportionate interest will suffer NAV dilution of up to 0.5% or $5 per $1,000 of NAV. This imposes constraints on our ability to raise capital when our common stock is trading below NAV per common share, as it generally has for the last several years. As noted above, the 1940 Act prohibits the issuance of multiple classes of "senior securities that are stock". We financed certain of our investments with borrowed money and capital from the issuance of senior securities, which will magnify the potential for gain or loss on amounts invested and may increase the risk of investing in us. The use of leverage, including through the issuance of senior securities that are debt or stock, magnifies the potential for gain or loss on amounts invested and, if we incur additional leverage, this potential will be further magnified. We have incurred leverage in the past and currently incur leverage through the Credit Facility, the 5.00% 2026 Notes, the 4.875% 2028 Notes, the 8.00% 2028 Notes and 7.875% 2030 Notes and, from time to time, may incur additional leverage to the extent permitted under the 1940 Act. The use of leverage is generally considered a speculative investment technique and increases the risks associated with investing in our securities. In the future, we may borrow from, and issue senior securities to, banks and other lenders. Holders of these senior securities will have fixed dollar claims on our assets that are superior to the claims of our common stockholders, and we would expect such holders to seek recovery against our assets in the event of a default. The following table illustrates the effect of leverage on returns from an investment in our common stock assuming various annual returns on our portfolio, net of expenses. The calculations in the table below are hypothetical and actual returns may be higher or lower than those appearing in the table below.
| Assumed Return on Our Portfolio (Net of Expenses)
| (10)% | (5)% | 0% | 5% | 10%
Corresponding return to common stockholder(A) | (25.96)% | (15.87)% | (5.79)% | 4.29% | 14.37%
(A)The hypothetical return to common stockholders is calculated by multiplying our total assets as of March 31, 2025 by the assumed rates of return and subtracting all interest on our debt expected to be paid during the twelve months following March 31, 2025, and then dividing the resulting difference by our total net assets attributable to common stock as of March 31, 2025. Based on $1.0 billion in total assets, no borrowings outstanding on our Credit Facility, $127.9 million of 5.00% 2026 Notes, at cost, $134.6 million of 4.875% 2028 Notes, at cost, $74.8 million of 8.00% 2028 Notes, at cost, $126.5 million of 7.875% 2030 Notes, at cost, and $499.1 million in net assets as of March 31, 2025. Based on an aggregate outstanding indebtedness of $463.7 million, at cost, as of March 31, 2025, the effective annual cash interest rate of 6.2% as of that date, our investment portfolio at fair value would have to produce an annual return of at least 3.0% to cover annual interest payments on the outstanding debt. |  |  |  |  |  |  |  |  |  |
Risks Related to Our Regulation and Structure [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to Our Regulation and Structure We will be subject to corporate-level tax if we are unable to satisfy the Code requirements for RIC qualification. To maintain our qualification as a RIC, we must maintain our status as a BDC and meet annual distribution, income source, and asset diversification requirements. The annual distribution requirement is satisfied if we distribute at least 90% of our Investment Company Taxable Income to our stockholders on an annual basis. Because we use leverage, we are subject to certain asset coverage ratio requirements under the 1940 Act and could, under certain circumstances, be restricted from making distributions necessary to qualify as a RIC. Warrants we may receive with respect to debt investments generally create original issue discount (“OID”), which we must recognize as ordinary income over the term of the debt investment. Similarly, PIK interest which is accrued generally over the term of the debt investment but not paid in cash, is recognized as ordinary income. Both OID and PIK interest will increase the amounts we are required to distribute to maintain our RIC status. Because such OIDs and PIK interest will not produce distributable cash for us at the same time as we are required to make distributions, we will need to use cash from other sources to satisfy such distribution requirements. As of March 31, 2025, we did not have investments with OID or a PIK feature. Additionally, we must meet asset diversification and income source requirements at the end of each calendar quarter. If we fail to meet these tests, we may need to quickly dispose of certain investments to prevent the loss of RIC status. Since most of our investments will be illiquid, such dispositions, if even possible, may not be made at prices advantageous to us and may result in substantial losses. If we fail to qualify as a RIC as of a calendar quarter or annually for any reason and become fully subject to U.S. federal corporate income tax, the resulting corporate taxes could substantially reduce our net assets, the amount of income available for distribution, and the actual amount distributed. Such a failure would have a material adverse effect on us and our common stock. Some of our debt investments may include success fees that would generally generate payments to us upon a change of control. Because the satisfaction of these success fees, and the ultimate payment of these fees, is uncertain and highly contingent, we generally only recognize them as income when the payment is received. Success fee amounts are characterized as ordinary income for tax purposes and, as a result, we are required to distribute such amounts to our stockholders to maintain our RIC status. If we do not invest a sufficient portion of our assets in “qualifying assets,” we could fail to qualify as a BDC under the 1940 Act or be precluded from investing according to our current business strategy. As a BDC, we may not acquire any assets other than “qualifying assets” unless, at the time of and after giving effect to such acquisition, at least 70% of our total assets, exclusive of Operating Assets, are qualifying assets, as defined in Section 55(a) of the 1940 Act. We believe that most of the investments that we may acquire in the future will constitute qualifying assets. However, we may be precluded from investing in what we believe to be attractive investments if such investments are not qualifying assets for purposes of the 1940 Act. If we do not invest a sufficient portion of our assets in qualifying assets, we could violate the 1940 Act provisions applicable to BDCs. As a result of such violation, specific rules under the 1940 Act could prevent us, for example, from making follow-on investments in existing portfolio companies (which could result in the dilution of our position) or could require us to dispose of investments at inappropriate times to come into compliance with the 1940 Act. If we need to dispose of such investments quickly, it could be difficult to dispose of such investments on favorable terms. We may not be able to find a buyer for such investments and, even if we do find a buyer, we may have to sell the investments at a substantial loss. Any such outcomes would have a material adverse effect on our business, financial condition, results of operations and cash flows. If we do not maintain our status as a BDC, we would be subject to regulation as a registered closed-end investment company under the 1940 Act. As a registered closed-end investment company, we would be subject to substantially more regulatory restrictions under the 1940 Act, which would significantly decrease our operating flexibility. Refer to “Business — Regulation as a BDC — Qualifying Assets” for additional information regarding qualifying assets. Provisions of the Delaware General Corporation Law and of our certificate of incorporation and bylaws could restrict a change in control and have an adverse impact on the price of our common stock. We are subject to provisions of the Delaware General Corporation Law that, in general, prohibit any business combination with a beneficial owner of 15% or more of our common stock for three years unless the holder’s acquisition of our stock was either approved in advance by our Board of Directors or ratified by our Board of Directors and stockholders owning two-thirds of our outstanding stock not owned by the acquiring holder. Although we believe these provisions collectively provide for an opportunity to receive higher bids by requiring potential acquirers to negotiate with our Board of Directors, they would apply even if the offer may be considered beneficial by some stockholders. We have also adopted other measures that may make it difficult for a third party to obtain control of us, including provisions of our certificate of incorporation classifying our Board of Directors in three classes serving staggered three-year terms, and provisions of our certificate of incorporation authorizing our Board of Directors to induce the issuance of additional shares of our stock. These provisions, as well as other provisions of our certificate of incorporation and bylaws, may delay, defer, or prevent a transaction or a change in control that might otherwise be in the best interests of our stockholders. We may not be permitted to declare a dividend or make any distribution to stockholders or repurchase shares until such time as we satisfy the asset coverage tests under the provisions of the 1940 Act that apply to BDCs. Regulations governing our operation as a BDC and RIC will affect our ability to raise, and the way in which we raise, additional capital or borrow for investment purposes, which may have a negative effect on our growth. As a result of the annual distribution requirement to qualify as a RIC, we may need to periodically access the capital markets to raise cash to fund new investments. We may issue senior securities representing indebtedness, including borrowing money from banks or other financial institutions, or senior securities that are stock, only in amounts such that our asset coverage, as defined in the 1940 Act, equals at least 150% after each such incurrence or issuance. Further, we may not be permitted to declare a dividend or make any distribution to our outstanding stockholders or repurchase shares until such time as we satisfy this test. Our ability to issue different types of securities is also limited. Compliance with these requirements may unfavorably limit our investment opportunities and reduce our ability in comparison to other companies to profit from favorable spreads between the rates at which we can borrow and the rates at which we can lend. As a BDC, therefore, we may issue equity at a rate more frequent than our privately owned competitors, which may lead to greater stockholder dilution. We have incurred leverage to generate capital to make additional investments. If the value of our assets declines, we may be unable to satisfy the asset coverage test under the 1940 Act, which could prohibit us from paying distributions and could prevent us from qualifying as a RIC. If we cannot satisfy the asset coverage test, we may be required to sell a portion of our investments and, depending on the nature of our debt financing, repay a portion of our indebtedness at a time when such sales and repayments may be disadvantageous. Such events, if they were to occur, could have a significant adverse effect on our business, financial condition, results of operations, and cash flows. |  |  |  |  |  |  |  |  |  |
Risks Related to Our External Management [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to Our External Management We are dependent upon our key management personnel and the key management personnel of the Adviser, particularly David Gladstone and David Dullum, and on the continued operations of the Adviser, for our future success. We have no employees. Our chief executive officer, chief operating officer, chief financial officer and treasurer, chief valuation officer, and the employees of the Adviser do not spend all of their time managing our activities and our investment portfolio. We are particularly dependent upon David Gladstone and David Dullum for their experience, skills, and networks. Our executive officers and the employees of the Adviser allocate some, and in some cases a material portion, of their time to businesses and activities that are not related to our business. We have no separate facilities and are completely reliant on the Adviser, which has significant discretion as to the implementation and execution of our business strategies and risk management practices. We are subject to the risk of discontinuation of the Adviser’s operations or termination of the Advisory Agreement and the risk that, upon such event, no suitable replacement will be found. We believe that our success depends to a significant extent upon the Adviser and that discontinuation of its operations or the loss of its key management personnel could have a material adverse effect on our ability to achieve our investment objectives. Our success depends on the Adviser’s ability to attract and retain qualified personnel in a competitive environment. The Adviser experiences competition in attracting and retaining qualified personnel, particularly investment professionals and senior executives, and we may be unable to maintain or grow our business if we cannot attract and retain such personnel. The Adviser’s ability to attract and retain personnel with the requisite credentials, experience and skills depends on several factors including, its ability to offer competitive wages, benefits and professional growth opportunities. The Adviser competes with investment funds (such as private equity funds and mezzanine funds) and traditional financial services companies for qualified personnel, many of which have greater resources than us. Searches for qualified personnel may divert management’s time from the operation of our business. Strain on the existing personnel resources of the Adviser, in the event that it is unable to attract experienced investment professionals and senior executives, could have a material adverse effect on our business. The Adviser can resign on 60 days’ notice, and we may not be able to find a suitable replacement within that time, resulting in a disruption in our operations that could adversely affect our financial condition, business and results of operations. The Adviser has the right to resign under the Advisory Agreement at any time upon not less than 60 days’ written notice, whether we have found a replacement or not. If the Adviser resigns, we may not be able to find a new investment adviser or hire internal management with similar expertise and ability to provide the same or equivalent services on acceptable terms within 60 days, or at all. If we are unable to do so quickly, our operations are likely to experience a disruption, our financial condition, business and results of operations as well as our ability to pay distributions are likely to be adversely affected and the market price of our common stock may decline. In addition, the coordination of our internal management and investment activities is likely to suffer if we are unable to identify and reach an agreement with a single institution or group of executives having the expertise possessed by the Adviser and its affiliates. Even if we are able to retain comparable management, whether internal or external, the integration of such management and their lack of familiarity with our investment objectives may result in additional costs and time delays that may adversely affect our business, financial condition, results of operations and cash flows. The Adviser’s liability is limited under the Advisory Agreement, and we are required to indemnify our investment adviser against certain liabilities, which may lead the Adviser to act in a riskier manner on our behalf than it would when acting for its own account. The Adviser has not assumed any responsibility to us other than to render the services described in the Advisory Agreement, and it will not be responsible for any action of our Board of Directors in declining to follow the Adviser’s advice or recommendations. Pursuant to the Advisory Agreement, the Adviser and its officers, managers, partners, agents, employees, controlling persons, members and any other person or entity affiliated with the Adviser will not be liable to us for their acts under the Advisory Agreement, absent willful misfeasance, bad faith or gross negligence in the performance of their duties or by reason of the reckless disregard of their duties and obligations under the Advisory Agreement. We have agreed to indemnify, defend and protect the Adviser and its officers, managers, partners, agents, employees, controlling persons, members and any other person or entity affiliated with the Adviser with respect to all damages, liabilities, costs and expenses arising out of or otherwise based upon the performance of any of the Adviser’s duties or obligations under the Advisory Agreement or otherwise as an investment adviser for us, and not arising out of willful misfeasance, bad faith or gross negligence in the performance of their duties or by reason of the reckless disregard of their duties and obligations under the Advisory Agreement. These protections may lead the Adviser to act in a riskier manner when acting on our behalf than it would when acting for its own account. Our incentive fee may induce the Adviser to make certain investments, including speculative investments. The management compensation structure that has been implemented under the Advisory Agreement may cause the Adviser to invest in high-risk investments or take other investment risks. In addition to its management fee, the Adviser is entitled under the Advisory Agreement to receive incentive compensation based in part upon our achievement of specified levels of income. In evaluating investments and other management strategies, the opportunity to earn incentive compensation based on net investment income may lead the Adviser to place undue emphasis on the maximization of net investment income at the expense of other criteria, such as preservation of capital, maintaining sufficient liquidity, or management of credit risk or market risk, to achieve higher incentive compensation. Investments with higher yield potential are generally riskier or more speculative. This could result in increased risk to the value of our investment portfolio. We may be obligated to pay the Adviser incentive compensation even if we incur a net decrease in net assets. The Advisory Agreement entitles the Adviser to incentive compensation for each fiscal quarter in an amount equal to a percentage of the excess of our net investment income for that quarter (before deducting the incentive fee) above a threshold return of 1.75% of our net assets, as adjusted, for that quarter. When calculating our incentive fee, our pre-incentive fee net investment income excludes realized losses and unrealized depreciation that we may incur in the fiscal quarter, even if such losses or depreciation result in a net decrease in net assets on our statement of operations for that quarter. Thus, we may be required to pay the Adviser incentive compensation for a fiscal quarter even if there is a decline in the value of our portfolio or we incur a net realized or unrealized loss for that quarter. For additional information on incentive compensation under the Advisory Agreement with the Adviser, see “Business — Investment Advisory and Management Agreement.” We may be required to pay the Adviser incentive compensation on income accrued, but not yet received in cash. The part of the incentive fee payable by us that relates to our net investment income is computed and paid on income that may include income that has been accrued but not yet received in cash, such as debt instruments with PIK interest. If a portfolio company defaults on a loan, it is possible that such accrued interest previously used in the calculation of the incentive fee will become uncollectible. Consequently, we may make incentive fee payments on income accruals that we may not collect in the future and with respect to which we do not have a clawback right against the Adviser. The Adviser’s failure to identify and invest in securities that meet our investment criteria or perform its responsibilities under the Advisory Agreement would likely adversely affect our ability for future growth. Our ability to achieve our investment objectives will depend on our ability to grow, which in turn will depend on the Adviser’s ability to identify and invest in securities that meet our investment criteria. Accomplishing this result on a cost-effective basis will be largely a function of the Adviser’s structuring of the investment process, its ability to provide competent and efficient services to us, and our access to financing on acceptable terms. The Adviser’s senior management team has substantial responsibilities under the Advisory Agreement. To grow, the Adviser will need to hire, train, supervise, and manage new employees successfully. Any failure to manage our future growth effectively would likely have a material adverse effect on our business, financial condition, results of operations, and cash flows. There are significant potential conflicts of interest, including with the Adviser, which could impact our investment returns. Our executive officers and directors, and the officers and directors of the Adviser, serve or may serve as officers, directors, or principals of entities that operate in the same or a related line of business as we do or of investment funds managed by our affiliates. Accordingly, they may have obligations to investors in those entities, the fulfillment of which might not be in our or our stockholders’ best interests. For example, Mr. Gladstone, our chairman and chief executive officer, is the chairman of the board and chief executive officer of the Adviser and Administrator, and the Affiliated Public Funds. Mr. Dullum, our president, is also an executive vice president of the Adviser. While portfolio managers and the officers and other employees of the Adviser devote as much time to the management of us as appropriate to enable the Adviser to perform its duties in accordance with the Advisory Agreement, the portfolio managers and other of the Adviser's officers may have conflicts in allocating their time and services among us, on the one hand, and other investment vehicles managed by the Adviser, on the other hand. These activities could be viewed as creating a conflict of interest insofar as the time and effort of the portfolio managers and the officers and employees of the Adviser will not be devoted exclusively to our business but will instead be allocated between our business and the management of these other investment vehicles. Moreover, the Adviser may establish or sponsor other investment vehicles which from time to time may have potentially overlapping investment objectives with ours and accordingly may invest in, whether principally or secondarily, asset classes we target. While the Adviser generally has broad authority to make investments on behalf of the investment vehicles that it advises, the Adviser has adopted investment allocation procedures to address these potential conflicts and intends to direct investment opportunities to the Company or the Affiliated Public Fund with the investment strategy that most closely fits the investment opportunity. Nevertheless, the management of the Adviser may face conflicts in the allocation of investment opportunities to other entities it manages. As a result, it is possible that we may not be given the opportunity to participate in certain investments made by other funds managed by the Adviser. In certain circumstances, we may make investments in a portfolio company in which one of our affiliates has or will have an investment, subject to satisfaction of any regulatory restrictions and, where required, the prior approval of our Board of Directors. As of March 31, 2025, our Board of Directors has approved the following types of transactions: •Our affiliate, Gladstone Commercial, may, under certain circumstances, lease property to portfolio companies that we do not control. We may pursue such transactions only if (i) the portfolio company is not controlled by us or any of our affiliates, (ii) the portfolio company satisfies the tenant underwriting criteria of Gladstone Commercial, and (iii) the transaction is approved by a majority of our independent directors and a majority of the independent directors of Gladstone Commercial. We expect that any such negotiations between Gladstone Commercial and our portfolio companies would result in lease terms consistent with the terms that the portfolio companies would be likely to receive were they not portfolio companies of ours. •Pursuant to the Co-Investment Order, we may co-invest, under certain circumstances, with certain of our affiliates, including Gladstone Capital, Gladstone Alternative and any future BDC or closed-end management investment company that is advised (or sub-advised if it controls the fund) by the Adviser, or any combination of the foregoing subject to the conditions in the Co-Investment Order. Certain of our officers, who are also officers of the Adviser, may from time to time serve as directors of certain of our portfolio companies. If an officer serves in such capacity for one of our portfolio companies, such officer will owe fiduciary duties to stockholders of the portfolio company, which duties may from time to time conflict with the interests of our stockholders. In the course of our investing activities, we will pay management and incentive fees to the Adviser and will reimburse the Administrator for certain expenses it incurs. As a result, investors in our common stock will invest on a “gross” basis and receive distributions on a “net” basis after expenses, resulting in, among other things, a lower rate of return than one might achieve through our investors themselves making direct investments. As a result of this arrangement, there may be times when the management team of the Adviser has interests that differ from those of our stockholders, giving rise to a conflict. In addition, as a BDC, we make available significant managerial assistance to our portfolio companies and provide other services to such portfolio companies. While neither we nor the Adviser currently receive fees in connection with managerial assistance, the Adviser and Gladstone Securities have, at various times, provided other services to certain of our portfolio companies and received fees for these other services. The Adviser is not obligated to provide credits of the base management fee or incentive fees, which could negatively impact our earnings and our ability to maintain our current level of distributions to our stockholders. The Advisory Agreement provides for a base management fee, based on our gross assets, and an incentive fee, that is based on our income and capital gains. Our Board of Directors has accepted in the past and may accept in the future non-contractual, unconditional, and irrevocable credits to reduce the annual 2.0% base management fee or the incentive fee, on a quarterly or annual basis. Any fees credited may not be recouped by the Adviser in the future. However, the Adviser is not required to issue these or other credits of fees under the Advisory Agreement. If the Adviser does not issue these credits in the future, it could negatively impact our earnings and may compromise our ability to maintain our current level of distributions to our stockholders, which could have a material adverse impact on our common stock price. Our business model is dependent upon developing and sustaining strong referral relationships with investment bankers, business brokers and other intermediaries and any change in our referral relationships may impact our business plan. We are dependent upon informal relationships with investment bankers, business brokers and traditional lending institutions to provide us with deal flow. If we fail to maintain our relationship with such funds or institutions, or if we fail to establish strong referral relationships with other funds, we will not be able to grow our portfolio of investments and fully execute our business plan. Our base management fee may induce the Adviser to incur leverage. The fact that our base management fee is payable based upon our gross assets, which would include any investments made with proceeds of borrowings, may encourage the Adviser to use leverage to make additional investments. Under certain circumstances, the use of increased leverage may increase the likelihood of default, which would disfavor holders of our securities. Given the subjective nature of the investment decisions made by the Adviser on our behalf, we will not be able to monitor this potential conflict of interest. |  |  |  |  |  |  |  |  |  |
Risks Related to an Investment in Our Securities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to an Investment in Our Securities There is a risk that you may not receive distributions or that distributions may not grow over time. Our current intention is to distribute up to 100% of our Investment Company Taxable Income to our stockholders by paying monthly distributions. We may retain some or all of our net realized long-term capital gains, if any, and designate them as deemed distributions to supplement our equity capital and support the growth of our portfolio, although our Board of Directors may determine to distribute these net realized long-term capital gains to our stockholders in cash. In addition, our Credit Facility restricts the amount of distributions we are permitted to make annually. We cannot assure investors that we will achieve investment results or maintain a tax status that will allow or require any specified level of cash distributions. Investing in our securities may involve an above average degree of risk. The investments we make in accordance with our investment objectives may result in a higher amount of risk than alternative investment options and a higher risk of volatility or loss of principal. Our investments in portfolio companies may be highly speculative, and therefore, an investment in our securities may not be suitable for someone with lower risk tolerance. Distributions to our common stockholders have included and may in the future include a return of capital. Our Board of Directors declares monthly common distributions each quarter based on estimates of Investment Company Taxable Income and capital gains for each fiscal year, which may differ, and in the past have differed, from actual results. Because our common distributions are based on estimates of Investment Company Taxable Income and capital gains that may differ from actual results, future common distributions payable to our common stockholders may include a return of capital. To the extent that we distribute amounts that exceed our accumulated earnings and profits, these distributions constitute a return of capital to the extent of the common stockholder’s adjusted tax basis in its shares of our common stock. A return of capital represents a return of a common stockholder’s original investment in shares of our common stock and should not be confused with a distribution from earnings and profits. Although return of capital distributions may not be taxable, such distributions may increase an investor’s tax liability for capital gains upon the sale of our common stock by reducing the investor’s tax basis in its shares of our common stock. Such returns of capital reduce our asset base and also adversely impact our ability to raise debt capital as a result of the leverage restrictions under the 1940 Act, which could have a material adverse impact on our ability to make new investments. Common stockholders may incur dilution if we sell shares of our common stock in one or more offerings at prices below the then current NAV per share. Absent stockholder approval, we are not able to access the capital markets in an offering of our securities at prices below the then-current NAV per share, due to restrictions applicable to BDCs under the 1940 Act. Should we decide to issue shares of common stock at a price below NAV per share in the future, we will seek the requisite approval of our stockholders at such time. If we were to sell shares of our common stock below NAV per share, such sales would result in an immediate dilution to the NAV per share. This dilution would occur as a result of the sale of shares at a price below the then current NAV per share of our common stock and a proportionately greater decrease in a common stockholder’s interest in our earnings and assets and voting interest in us than the increase in our assets resulting from such issuance. The greater the difference between the sale price and the NAV per share at the time of the offering, the more significant the dilutive impact would be. Because the number of shares of common stock that could be so issued and the timing of any issuance is not currently known, the actual dilutive effect, if any, cannot be currently predicted. However, if, for example, we sold an additional 10% of our common stock at a 5% discount from NAV, an existing common stockholder who did not participate in that offering for its proportionate interest would suffer NAV dilution of up to 0.5% or $5 per $1,000 of NAV. |  |  |  |  |  |  |  |  |  |
Risks Related to the 5.00% 2026 Notes, 4.875% 2028 Notes and 8.00% 2028 Notes (collectively, the "Notes") [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | Risks Related to the 5.00% 2026 Notes, 4.875% 2028 Notes, 8.00% 2028 Notes and 7.875% 2030 Notes (collectively, the "Notes") The Notes are unsecured and therefore are effectively subordinated to any secured indebtedness we may incur in the future and will rank pari passu with, or equal to, all outstanding and future unsecured indebtedness issued by us and our general liabilities (total liabilities, less debt). The Notes are not secured by any of our assets or any of the assets of our subsidiaries. As a result, the Notes are effectively subordinated to any secured indebtedness we may incur in the future (or any indebtedness that is initially unsecured to which we subsequently grant security) to the extent of the value of the assets securing such indebtedness. In any liquidation, dissolution, bankruptcy or other similar proceeding, the holders of any of our existing or future secured indebtedness and the secured indebtedness of our subsidiaries may assert rights against the assets pledged to secure that indebtedness to receive full payment of their indebtedness before the assets may be used to pay other creditors, including the holders of the Notes. In addition, the Notes will rank pari passu with, or equal to, all outstanding and future unsecured indebtedness issued by us and our general liabilities (total liabilities, less debt). The Notes are structurally subordinated to the indebtedness and other liabilities of our subsidiaries. The Notes are obligations exclusively of the Company and not of any of our subsidiaries. None of our subsidiaries is a guarantor of the Notes and the Notes are not required to be guaranteed by any subsidiaries we may acquire or create in the future. Except to the extent we are a creditor with recognized claims against our subsidiaries, all claims of creditors of our subsidiaries will have priority over our equity interests in such subsidiaries (and therefore the claims of our creditors, including holders of the Notes) with respect to the assets of such subsidiaries. Even if we are recognized as a creditor of one or more of our subsidiaries, our claims would still be effectively subordinated to any security interests in the assets of any such subsidiary and to any indebtedness or other liabilities of any such subsidiary senior to our claims. Consequently, the Notes are structurally subordinated to all indebtedness and other liabilities of any of our subsidiaries and any subsidiaries that we may in the future acquire or establish. Our wholly-owned subsidiary, Business Investment, is the obligor under our Credit Facility, which is structurally senior to the Notes. In addition, our subsidiaries may incur substantial additional indebtedness in the future, all of which would be structurally senior to the Notes. The indenture under which the Notes were issued contains limited protection for holders of the Notes. The indenture under which the Notes were issued offers limited protection to holders of the Notes. The terms of the indenture and the Notes do not restrict our or any of our subsidiaries’ ability to engage in, or otherwise be a party to, a variety of corporate transactions, circumstances or events that could have an adverse impact on your investment in the Notes. In particular, the terms of the indenture and the Notes do not place any restrictions on our or our subsidiaries’ ability to: •issue securities or otherwise incur additional indebtedness or other obligations, including (1) any indebtedness or other obligations that would be equal in right of payment to the Notes, (2) any indebtedness or other obligations that would be secured and therefore rank effectively senior in right of payment to the Notes to the extent of the values of the assets securing such debt, (3) indebtedness of ours that is guaranteed by one or more of our subsidiaries and which therefore is structurally senior to the Notes and (4) securities, indebtedness or obligations issued or incurred by our subsidiaries that would be senior to our equity interests in our subsidiaries and therefore rank structurally senior to the Notes with respect to the assets of our subsidiaries, in each case other than an incurrence of indebtedness or other obligation that would cause a violation of Section 18(a)(1)(A) as modified by Section 61(a)(2) of the 1940 Act or any successor provisions, whether or not we continue to be subject to such provisions of the 1940 Act, which generally prohibit us incurring additional debt or issuing additional debt or preferred securities, unless our asset coverage, as defined in the 1940 Act, equals at least 150% after such incurrence or issuance; •pay dividends on, or purchase or redeem or make any payments in respect of, capital stock or other securities ranking junior in right of payment to the Notes, including preferred stock and any subordinated indebtedness, in each case other than dividends, purchases, redemptions or payments that would cause our asset coverage to fall below the threshold specified in Section 18(a)(1)(B) as modified by Section 61(a)(2) of the 1940 Act or any successor provisions thereto, whether or not we are subject to such provisions of the 1940 Act, giving effect to any no-action relief granted by the SEC to another BDC and upon which we may reasonably rely (or to us if we determine to seek such similar SEC no-action or other relief) permitting the BDC to declare any cash dividend or distribution notwithstanding the prohibition contained in Section 18(a)(1)(B) as modified by Section 61(a)(2) of the 1940 Act to maintain the BDC’s status as a RIC under Subchapter M of the Code; •sell assets (other than certain limited restrictions on our ability to consolidate, merge or sell all or substantially all of our assets); •enter into transactions with affiliates; •create liens (including liens on the shares of our subsidiaries) or enter into sale and leaseback transactions; •make investments; or •create restrictions on the payment of dividends or other amounts to us from our subsidiaries. In addition, the indenture and the Notes do not require us to make an offer to purchase the Notes in connection with a change of control or any other event. Furthermore, the terms of the indenture and the Notes do not protect holders of the Notes in the event that we experience changes (including significant adverse changes) in our financial condition, results of operations or credit ratings, if any, as they do not require that we or our subsidiaries adhere to any financial tests or ratios or specified levels of net worth, revenues, income, cash flow, or liquidity. Our ability to recapitalize, incur additional debt (including additional debt that matures prior to the maturity of the Notes) and take a number of other actions that are not limited by the terms of the Notes may have important consequences for you as a holder of the Notes, including making it more difficult for us to satisfy our obligations with respect to the Notes or negatively affecting the trading value of the Notes. Other debt we issue or incur in the future could contain more protections for its holders than the indenture and the Notes, including additional covenants and events of default. The issuance or incurrence of any such debt with incremental protections could affect the market for, trading levels, and prices of the Notes. An active trading market for the Notes may not exist, which could limit your ability to sell the Notes or affect the market price of the Notes. An active trading market for the Notes may not exist in the future and holders may not be able to sell their Notes. Even if an active trading market does exist, the Notes may trade at a discount from their initial offering price depending on prevailing interest rates, the market for similar securities, our credit ratings, if any, general economic conditions, our financial condition, performance and prospects and other factors. To the extent an active trading market does not exist, the liquidity and trading price for the Notes may be harmed. Accordingly, holders of the Notes may be required to bear the financial risk of an investment in the Notes for an indefinite period of time. If we default on our obligations to pay our other indebtedness, we may not be able to make payments on the Notes. Any default under the agreements governing our indebtedness, including a default under the Credit Facility or other indebtedness to which we may be a party, that is not waived by the required lenders or holders, and the remedies sought by the holders of such indebtedness could make us unable to pay principal, premium, if any, and interest on the Notes and substantially decrease the market value of the Notes. If we are unable to generate sufficient cash flow and are otherwise unable to obtain funds necessary to meet required payments of principal, premium, if any, and interest on our indebtedness, or if we otherwise fail to comply with the various covenants, including financial and operating covenants, in the instruments governing our indebtedness, we could be in default under the terms of the agreements governing such indebtedness, including the Notes. In the event of such default, the holders of such indebtedness could elect to declare all the funds borrowed thereunder to be due and payable, together with accrued and unpaid interest, the lenders under the Credit Facility or other debt we may incur in the future could elect to terminate their commitments, cease making further loans and institute foreclosure proceedings against our assets, and we could be forced into bankruptcy or liquidation. If our operating performance declines, we may in the future need to refinance or restructure our debt, including the Notes, sell assets, reduce or delay capital investments, seek to raise additional capital or seek to obtain waivers from the required lenders under the Credit Facility or other debt that we may incur in the future to avoid being in default. If we are unable to implement one or more of these alternatives, we may not be able to meet our payment obligations under the Notes or our other debt. If we breach our covenants under the Credit Facility or other debt and seek a waiver, we may not be able to obtain a waiver from the required lenders or holders. If this occurs, we would be in default under the Credit Facility or other debt, the lenders or holders could exercise their rights as described above, and we could be forced into bankruptcy or liquidation. If we are unable to repay debt, lenders having secured obligations, including the lenders under the Credit Facility, could proceed against the collateral securing the debt. Because the Credit Facility has, and any future credit facilities will likely have, customary cross-default provisions, if the indebtedness under the Notes or the Credit Facility or under any future credit facility is accelerated, we may be unable to repay or finance the amounts due. We may choose to redeem the Notes when prevailing interest rates are relatively low. At any time with respect to the 5.00% 2026 Notes and the 4.875% 2028 Notes, on or after August 1, 2025, with respect to the 8.00% 2028 Notes and on or after February 1, 2027, with respect to the 7.875% 2030 Notes, we may choose to redeem the Notes from time to time, especially if prevailing interest rates are lower than the rate borne by the Notes. If prevailing rates are lower at the time of redemption, and we redeem the Notes, you likely would not be able to reinvest the redemption proceeds in a comparable security at an effective interest rate as high as the interest rate on the Notes being redeemed. Our redemption right also may adversely impact your ability to sell the Notes as the optional redemption date or period approaches. A downgrade, suspension or withdrawal of any credit rating assigned by a rating agency to us or the Notes could cause the liquidity or market value of the Notes to decline significantly. Any credit rating is an assessment by the assigning rating agency of our ability to pay our debts when due. Consequently, real or anticipated changes in any credit ratings will generally affect the market value of the Notes. These credit ratings may not reflect the potential impact of risks relating to the structure or marketing of the Notes. Credit ratings are not a recommendation to buy, sell or hold any security, and may be revised or withdrawn at any time by the issuing organization in its sole discretion. There can be no assurance that any credit ratings will remain for any given period of time or that such credit ratings will not be lowered or withdrawn entirely by the rating agencies if in their judgment future circumstances relating to the basis of the credit ratings, such as adverse changes in our Company, so warrant. |  |  |  |  |  |  |  |  |  |
General Risk Factors [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk [Text Block] |  |  |  |  |  |  |  |  |  | General Risk Factors Cybersecurity risks and cyber incidents may adversely affect our business by causing a disruption to our operations, or the operations of businesses in which we invest, a compromise or corruption of our confidential information and/or damage to our business relationships, all of which could negatively impact our business, financial condition and operating results. Maintaining our network security is of critical importance because our systems store highly confidential financial models and portfolio company information. Although we have implemented, and will continue to implement, security measures, our technology platform may be vulnerable to intrusion, computer viruses or similar disruptive problems caused by cyber-attacks, including those employing artificial intelligence. A cyber incident is considered to be any adverse event that threatens the confidentiality, integrity or availability of our information resources or those of our portfolio companies. These incidents may be an intentional attack or an unintentional event and could involve gaining unauthorized access to our information systems or those of our portfolio companies for purposes of misappropriating assets, stealing confidential information, corrupting data or causing operational disruption. The result of these incidents may include disrupted operations, misstated or unreliable financial data, liability for stolen assets or information, increased cybersecurity protection and insurance costs, litigation and damage to our business relationships or those of our portfolio companies. As our and our portfolio companies’ reliance on technology has increased, so have the risks posed to our information systems, both internal and those provided to us by third-party service providers, and the information systems of our portfolio companies. We have implemented processes, procedures and internal controls to help mitigate cybersecurity risks and cyber intrusions, but these measures, as well as our increased awareness of the nature and extent of a risk of a cyber incident, do not guarantee that a cyber incident will not occur and/or that our financial results, operations or confidential information will not be negatively impacted by such an incident. In addition, any such incident, disruption or other loss of information could result in legal claims or proceedings, liability under laws that protect the privacy of personal information, and regulatory penalties, disrupt our operations, and damage our and our Adviser’s reputations, resulting in a loss of confidence in our services and our Adviser’s services, which could adversely affect our business. We are subject to risks associated with artificial intelligence and machine learning technology. Recent technological advances in artificial intelligence and machine learning technology pose risks to our Company and our portfolio companies. We and our portfolio companies could be exposed to the risks of artificial intelligence and machine learning technology if third-party service providers or any counterparties, whether or not known to us, also use artificial intelligence and machine learning technology in their business activities. We and our portfolio companies may not be in a position to control the use of artificial intelligence and machine learning technology in third-party products or services. Use of artificial intelligence and machine learning technology could include the input of confidential information in contravention of applicable policies, contractual or other obligations or restrictions, resulting in such confidential information becoming partly accessible by other third-party artificial intelligence and machine learning technology applications and users. Independent of its context of use, artificial intelligence and machine learning technology is generally highly reliant on the collection and analysis of large amounts of data, and it is not possible or practicable to incorporate all relevant data into the model that artificial intelligence and machine learning technology utilizes to operate. Certain data in such models will inevitably contain a degree of inaccuracy and error—potentially materially so—and could otherwise be inadequate or flawed, which would be likely to degrade the effectiveness of artificial intelligence and machine learning technology. To the extent that we or our portfolio companies are exposed to the risks of artificial intelligence and machine learning technology use, any such inaccuracies or errors could have adverse impacts on our Company or our investments. Artificial intelligence and machine learning technology and its applications, including in the private investment and financial sectors, continue to develop rapidly, and it is impossible to predict the future risks that may arise from such developments. We are subject to risks related to corporate social responsibility. Our business (including that of our portfolio companies) faces increasing public scrutiny related to environmental, social and governance (“ESG”) activities, which are increasingly considered to contribute to the long-term sustainability of a company’s performance. A variety of organizations measure the performance of companies on ESG topics, and the results of these assessments are widely publicized. Adverse incidents with respect to ESG activities could impact the value of our brand, our relationship with future portfolio companies, the cost of our operations and relationships with investors, all of which could adversely affect our business and results of operations. Additionally, new regulatory initiatives related to ESG that are applicable to us and our portfolio companies could adversely affect our business. Compliance with these rules may be onerous and expensive. Further, compliance with any new laws, regulations or disclosure obligations increases our regulatory burden and could make compliance more difficult and expensive, affect the manner in which we or our portfolio companies conduct our businesses and adversely affect our profitability. We are dependent on information systems and systems failures could significantly disrupt our business, which may, in turn, negatively affect the market price of our common stock and our ability to pay dividends. Our business is dependent on our and third parties’ communications and information systems. Any failure or interruption of those systems, including as a result of the termination of an agreement with any third-party service providers, could cause delays or other problems in our activities. Our financial, accounting, data processing, backup or other operating systems and facilities may fail to operate properly or become disabled or damaged as a result of a number of factors including events that are wholly or partially beyond our control and adversely affect our business. There could be: •sudden electrical or telecommunications outages; •natural disasters such as earthquakes, tornadoes and hurricanes; •disease pandemics; •events arising from local or larger scale political or social matters, including terrorist acts; and •cyber-attacks. These events, in turn, could have a material adverse effect on our operating results and negatively affect the market price of our common stock and our ability to pay dividends to our stockholders. Changes in laws or regulations governing our operations, or changes in the interpretation thereof, and any failure by us to comply with laws or regulations governing our operations may adversely affect our business. We, and our portfolio companies, are subject to regulation by laws at the local, state and federal levels. These laws and regulations, as well as their interpretation, may be changed from time to time. Accordingly, any change in these laws or regulations, or their interpretation, or any failure by us or our portfolio companies to comply with these laws or regulations may adversely affect our business. We may experience fluctuations in our quarterly and annual operating results. We may experience fluctuations in our quarterly and annual operating results due to a number of factors, including, among others, variations in our investment income, the level of our expenses, variations in and the timing of the recognition of realized and unrealized gains or losses, rapidly changing valuation of our portfolio companies, placing and removing investments on non-accrual status, the degree to which we encounter competition in our markets, the ability to sell investments at attractive terms, the ability to fund and close suitable investments, and general economic conditions, including the impacts of inflation and elevated interest rates. The majority of our portfolio companies are in industries that are directly impacted by inflation, such as manufacturing and consumer goods and services. Our portfolio companies may not be able to pass on to customers increases in their costs of production which could greatly affect their operating results, impacting their ability to service and repay our loans. In addition, any potential future decreases in our portfolio companies’ operating results due to inflation could adversely impact the fair value of those investments. Any decreases in the fair value of our investments could result in future realized and unrealized losses and therefore reduce our net assets. As a result of these factors, results for any period should not be relied upon as being indicative of performance in future periods. |  |  |  |  |  |  |  |  |  |
7.125% Series A Cumulative Term Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 40,000,000 |
Senior Securities Coverage per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,214 |
Preferred Stock Liquidating Preference |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00 |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25.60 |
6.75% Series B Cumulative Term Preferred Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 41,400,000 | $ 41,400,000 | $ 41,400,000 |
Senior Securities Coverage per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,373 | $ 2,356 | $ 2,214 |
Preferred Stock Liquidating Preference |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00 | 25.00 | 25.00 |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25.20 | $ 26.00 | $ 24.43 |
6.50% Series C Cumulative Term Preferred Stock due 2022 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 40,250,000 | $ 40,250,000 | $ 40,250,000 |
Senior Securities Coverage per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,373 | $ 2,356 | $ 2,214 |
Preferred Stock Liquidating Preference |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00 | 25.00 | 25.00 |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25.33 | $ 25.64 | $ 23.92 |
6.25% Series D Cumulative Term Preferred Stock due 2023 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 57,500,000 | $ 57,500,000 | $ 57,500,000 | $ 57,500,000 |  |
Senior Securities Coverage per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,938 | $ 3,091 | $ 2,373 | $ 2,356 |  |
Preferred Stock Liquidating Preference |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00 | 25.00 | 25.00 | 25.00 |  |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 20.46 | $ 25.38 | $ 25.22 | $ 25.43 |  |
6.375% Series E Cumulative Term Preferred Stock due 2025 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 94,371,325 | $ 74,750,000 | $ 74,750,000 |  |  |  |
Senior Securities Coverage per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,486 | $ 2,938 | $ 3,091 |  |  |  |
Preferred Stock Liquidating Preference |  |  |  |  |  |  |  |  |  |  |  |  |  | 25.00 | 25.00 | 25.00 |  |  |  |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 25.44 | $ 19.52 | $ 25.55 |  |  |  |
Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  | $ 0 |  |  |  | $ 67,000,000 |  |  |  | $ 0 | $ 67,000,000 | $ 35,200,000 | $ 0 | $ 22,400,000 | $ 49,200,000 | $ 53,000,000 | $ 107,000,000 | $ 69,700,000 | $ 95,000,000 |
Senior Securities Coverage per Unit |  | $ 2,044 |  |  |  | $ 2,190 |  |  |  | $ 2,044 | $ 2,190 | $ 2,447 | $ 2,529 | $ 3,980 | $ 9,935 | $ 9,976 | $ 5,257 | $ 6,613 | $ 4,838 |
5.00% Notes Due 2026 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  | $ 127,937,500 |  |  |  | $ 127,937,500 |  |  |  | $ 127,937,500 | $ 127,937,500 | $ 127,937,500 | $ 127,937,500 | $ 127,937,500 |  |  |  |  |  |
Senior Securities Coverage per Unit |  | $ 2,044 |  |  |  | $ 2,190 |  |  |  | $ 2,044 | $ 2,190 | $ 2,447 | $ 2,529 | $ 3,980 |  |  |  |  |  |
Preferred Stock Liquidating Preference |  | $ 25.00 |  |  |  | $ 25.00 |  |  |  | 25.00 | 25.00 | 25.00 | 25.00 | 25.00 |  |  |  |  |  |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  | $ 24.93 | $ 24.16 | $ 23.47 | $ 25.13 | $ 25.85 |  |  |  |  |  |
4.875% Notes due 2028 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  | $ 134,550,000 |  |  |  | $ 134,550,000 |  |  |  | $ 134,550,000 | $ 134,550,000 | $ 134,550,000 | $ 134,550,000 |  |  |  |  |  |  |
Senior Securities Coverage per Unit |  | $ 2,044 |  |  |  | $ 2,190 |  |  |  | $ 2,044 | $ 2,190 | $ 2,447 | $ 2,529 |  |  |  |  |  |  |
Preferred Stock Liquidating Preference |  | $ 25.00 |  |  |  | $ 25.00 |  |  |  | 25.00 | 25.00 | 25.00 | 25.00 |  |  |  |  |  |  |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  | $ 23.33 | $ 22.95 | $ 23.00 | $ 25.07 |  |  |  |  |  |  |
8.00% Notes Due 2028 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  | $ 74,750,000 |  |  |  | $ 74,750,000 |  |  |  | $ 74,750,000 | $ 74,750,000 |  |  |  |  |  |  |  |  |
Senior Securities Coverage per Unit |  | $ 2,044 |  |  |  | $ 2,190 |  |  |  | $ 2,044 | $ 2,190 |  |  |  |  |  |  |  |  |
Preferred Stock Liquidating Preference |  | $ 25.00 |  |  |  | $ 25.00 |  |  |  | 25.00 | 25.00 |  |  |  |  |  |  |  |  |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  | $ 25.86 | $ 25.86 |  |  |  |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt, Title [Text Block] |  |  |  |  |  |  |  |  |  | 8.00% Notes due 2028 |  |  |  |  |  |  |  |  |  |
Long Term Debt, Structuring [Text Block] |  |  |  |  |  |  |  |  |  | In May 2023, we completed a public offering of the 8.00% 2028 Notes with an aggregate principal amount of $74.8 million, which resulted in net proceeds of approximately $72.3 million after deducting underwriting discounts, commissions and offering costs borne by us. The 8.00% 2028 Notes are traded under the ticker symbol “GAINL” on Nasdaq. The 8.00% 2028 Notes will mature on August 1, 2028 and may be redeemed in whole or in part at any time or from time to time at the Company’s option on or after August 1, 2025. The 8.00% 2028 Notes bear interest at a rate of 8.00% per year (which equates to $6.0 million per year), payable quarterly in arrears. |  |  |  |  |  |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] |  |  |  |  |  |  |  |  |  | The indenture relating to the 8.00% 2028 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 8.00% 2028 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |  |  |  |  |  |
7.875% Notes Due 2030 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  | $ 126,500,000 |  |  |  |  |  |  |  | $ 126,500,000 |  |  |  |  |  |  |  |  |  |
Senior Securities Coverage per Unit |  | $ 2,044 |  |  |  |  |  |  |  | $ 2,044 |  |  |  |  |  |  |  |  |  |
Preferred Stock Liquidating Preference |  | $ 25.00 |  |  |  |  |  |  |  | 25.00 |  |  |  |  |  |  |  |  |  |
Senior Securities Average Market Value per Unit |  |  |  |  |  |  |  |  |  | $ 25.38 |  |  |  |  |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt, Title [Text Block] |  |  |  |  |  |  |  |  |  | 7.875% Notes due 2030 |  |  |  |  |  |  |  |  |  |
Long Term Debt, Structuring [Text Block] |  |  |  |  |  |  |  |  |  | In December 2024, we completed a public offering of the 7.875% 2030 Notes with an aggregate principal amount of $126.5 million, which resulted in net proceeds of approximately $122.4 million after deducting underwriting discounts, commissions and offering costs borne by us. The 7.875% 2030 Notes are traded under the ticker symbol “GAINI” on Nasdaq. The 7.875% 2030 Notes will mature on February 1, 2030 and may be redeemed in whole or in part at any time or from time to time at the Company’s option on or after February 1, 2027. The 7.875% 2030 Notes bear interest at a rate of 7.875% per year (which equates to $10.0 milli on per year), payable quarterly in arrears. |  |  |  |  |  |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] |  |  |  |  |  |  |  |  |  | The indenture relating to the 7.875% 2030 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 7.875% 2030 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |  |  |  |  |  |
Secured Debt [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Securities Amount |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,095,785 | $ 5,095,785 | $ 5,095,785 | $ 5,095,785 | $ 5,095,785 | $ 5,095,785 | $ 5,095,785 |
Senior Securities Coverage per Unit |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,529 | $ 3,980 | $ 9,935 | $ 9,976 | $ 5,257 | $ 6,613 | $ 4,838 |
Notes 2026 Five Point Zero [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt, Title [Text Block] |  |  |  |  |  |  |  |  |  | 5.00% Notes due 2026 |  |  |  |  |  |  |  |  |  |
Long Term Debt, Structuring [Text Block] |  |  |  |  |  |  |  |  |  | In March 2021, we completed a public offering of the 5.00% 2026 Notes with an aggregate principal amount of $127.9 million, which resulted in net proceeds of approximately $123.8 million after deducting underwriting discounts, commissions and offering costs borne by us. The 5.00% 2026 Notes are traded under the ticker symbol “GAINN” on Nasdaq. The 5.00% 2026 Notes will mature on May 1, 2026 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 5.00% 2026 Notes bear interest at a rate of 5.00% per year (which equates to $6.4 million per year), payable quarterly in arrears. |  |  |  |  |  |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] |  |  |  |  |  |  |  |  |  | The indenture relating to the 5.00% 2026 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 5.00% 2026 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |  |  |  |  |  |
Notes 2028 Four Point Eight Seven Five [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long Term Debt, Title [Text Block] |  |  |  |  |  |  |  |  |  | 4.875% Notes due 2028 |  |  |  |  |  |  |  |  |  |
Long Term Debt, Structuring [Text Block] |  |  |  |  |  |  |  |  |  | In August 2021, we completed a public offering of the 4.875% 2028 Notes with an aggregate principal amount of $134.6 million, which resulted in net proceeds of approximately $131.3 million after deducting underwriting discounts, commissions and offering costs borne by us. The 4.875% 2028 Notes are traded under the ticker symbol “GAINZ” on Nasdaq. The 4.875% 2028 Notes will mature on November 1, 2028 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 4.875% 2028 Notes bear interest at a rate of 4.875% per year (which equates to $6.6 million per year), payable quarterly in arrears. |  |  |  |  |  |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] |  |  |  |  |  |  |  |  |  | The indenture relating to the 4.875% 2028 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 4.875% 2028 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |  |  |  |  |  |

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