XML 64 R53.htm IDEA: XBRL DOCUMENT
v3.25.3

REGISTRATION STATEMENT AND COMMON EQUITY OFFERINGS (Details) - USD ($) | 3 Months Ended | 6 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2025 | Sep. 30, 2025 | Sep. 30, 2024 | May 31, 2024 | Feb. 28, 2024 | Aug. 31, 2022
Government Assistance [Line Items] |  |  |  |  |  |
Net proceeds |  | $ 38,893,000 | $ 0 |  |  |
Registration Statement on Form N-2 (File No. 333-277452) |  |  |  |  |  |
Government Assistance [Line Items] |  |  |  |  |  |
Securities, aggregate value authorized |  |  |  |  | $ 450,000,000 |
Securities, remaining capacity of aggregate value authorized | $ 282,600,000 | 282,600,000 |  |  |  |
2024 Common Stock ATM Program |  |  |  |  |  |
Government Assistance [Line Items] |  |  |  |  |  |
Sale of stock, aggregate offering price authorized |  |  |  | $ 75,000,000.0 |  |
Sale of stock, remaining capacity of authorized offering price | $ 34,100,000 | $ 34,100,000 |  |  |  |
2022 Common Stock ATM Program |  |  |  |  |  |
Government Assistance [Line Items] |  |  |  |  |  |
Sale of stock, aggregate offering price authorized |  |  |  |  |  | $ 50,000,000
Sale of stock, number of shares sold (in shares) |  |  | 0 |  |  |
Common Stock ATM Program |  |  |  |  |  |
Government Assistance [Line Items] |  |  |  |  |  |
Sale of stock, number of shares sold (in shares) | 2,238,361 | 2,753,656 |  |  |  |
Sale of stock, weighted-average gross price per share (in USD per share) | $ 14.10 | $ 14.12 |  |  |  |
Sale of stock, weighted-average net price per share after deducting commissions and offering costs (in USD per share) | $ 13.90 | $ 13.93 |  |  |  |
Gross proceeds | $ 31,600,000 | $ 38,900,000 |  |  |  |
Net proceeds | $ 31,100,000 | $ 38,400,000 |  |  |  |

X
- Definition Sale Of Stock, Aggregate Offering Price Authorized + References No definition available. + Details
Name: | gain_SaleOfStockAggregateOfferingPriceAuthorized
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Sale Of Stock, Aggregate Value Of Securities Authorized + References No definition available. + Details
Name: | gain_SaleOfStockAggregateValueOfSecuritiesAuthorized
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Sale Of Stock, Remaining Capacity Of Aggregate Value Of Securities Authorized + References No definition available. + Details
Name: | gain_SaleOfStockRemainingCapacityOfAggregateValueOfSecuritiesAuthorized
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Sale Of Stock, Remaining Capacity Of Authorized Offering Price + References No definition available. + Details
Name: | gain_SaleOfStockRemainingCapacityOfAuthorizedOfferingPrice
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Sale Of Stock, Weighted-Average Gross Price Per Share + References No definition available. + Details
Name: | gain_SaleOfStockWeightedAverageGrossPricePerShare
Namespace Prefix: | gain_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Sale Of Stock, Weighted-Average Net Price Per Share After Deducting Commissions And Offering Costs + References No definition available. + Details
Name: | gain_SaleOfStockWeightedAverageNetPricePerShareAfterDeductingCommissionsAndOfferingCosts
Namespace Prefix: | gain_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 832 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483507/832-10-50-3 + Details
Name: | us-gaap_GovernmentAssistanceLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 14 -Subparagraph (a) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-14 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cash received on stock transaction after deduction of issuance costs. + References No definition available. + Details
Name: | us-gaap_SaleOfStockConsiderationReceivedOnTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=gain_RegistrationStatementOnFormN2FileNo.333277452Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=gain_CommonStockATMProgram2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=gain_CommonStockATMProgram2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=gain_CommonStockATMProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |