XML 55 R45.htm IDEA: XBRL DOCUMENT
v3.23.3

BORROWINGS - Revolving Line of Credit Narrative (Details) - USD ($) $ in Millions |  |  | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Apr. 10, 2023 | Mar. 08, 2021 | Sep. 30, 2023 | Mar. 31, 2023
Debt Instrument [Line Items] |  |  |  |
Indebtedness asset coverage on our senior securities |  |  | 211.50% | 244.70%
Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Unused fee percentage |  |  |  | 1.00%
Credit Facility |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Term |  | 2 years |  |
Credit Facility | Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Unused fee percentage |  |  | 0.75% |
Credit Facility | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Covenant, required minimum net worth of mandatory redeemable term preferred stock |  |  | $ 210.0 |
Covenant, required minimum net worth of mandatory redeemable term preferred stock, plus percent of all equity and subordinated debt raised |  |  | 50.00% |
Covenant, required minimum net worth of mandatory redeemable term preferred stock, minus percent of any equity or subordinated debt redeemed or retired |  |  | 50.00% |
Covenant, required minimum net worth of mandatory redeemable term preferred stock, plus percent of all equity and subordinated debt raised, minus percent of any equity or subordinated debt redeemed or retired |  |  | $ 328.5 |
Indebtedness asset coverage on our senior securities |  |  | 211.50% |
Senior security, indebtedness, asset coverage amount |  |  | $ 805.9 |
Credit Facility | Line of Credit | Revolving Line of Credit | Minimum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Indebtedness asset coverage on our senior securities |  |  | 150.00% |
Credit Facility | Line of Credit | Revolving Line of Credit | Less than or Equal to 50% of Commitment |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Unused fee percentage |  |  | 0.50% |
Credit Facility | Line of Credit | Revolving Line of Credit | Greater Than 50% But Less Than or Equal to 65% of Commitment |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Unused fee percentage |  |  | 0.75% |
Credit Facility | Line of Credit | Revolving Line of Credit | Greater Than 65% Of Commitment |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Unused fee percentage |  |  | 1.00% |
Credit Facility | Secured Overnight Financing Rate (SOFR) | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate | 0.11% |  | 3.25% |
Debt instrument, variable rate floor |  |  | 0.35% | 0.50%
Credit Facility | SOFR, Tranche One | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 2.85% |
Credit Facility | SOFR, Tranche Two | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 3.10% |
Credit Facility | SOFR, Thereafter | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 3.35% |
Credit Facility | SOFR, Thereafter, Adjustment | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate |  |  | 0.11% |
Credit Facility | LIBOR | Line of Credit | Revolving Line of Credit |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate |  |  |  | 2.94%

X
- Definition Debt Instrument, Covenant, Net Worth Of Mandatory Redeemable Term Preferred Stock, Plus Percent of All Equity and Subordinated Debt Raised, Minus Any Equity Or Subordinated Debt Redeemed or Retired + References No definition available. + Details
Name: | gain_DebtInstrumentCovenantNetWorthOfMandatoryRedeemableTermPreferredStockPlusPercentOfAllEquityAndSubordinatedDebtRaisedMinusAnyEquityOrSubordinatedDebtRedeemedOrRetired
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Instrument, Covenant, Required Minimum Net Worth Of Mandatory Redeemable Term Preferred Stock + References No definition available. + Details
Name: | gain_DebtInstrumentCovenantRequiredMinimumNetWorthOfMandatoryRedeemableTermPreferredStock
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Instrument, Covenant, Required Minimum Net Worth Of Mandatory Redeemable Term Preferred Stock, Minus Percent of Any Equity Or Subordinated Debt Redeemed Or Retired + References No definition available. + Details
Name: | gain_DebtInstrumentCovenantRequiredMinimumNetWorthOfMandatoryRedeemableTermPreferredStockMinusPercentOfAnyEquityOrSubordinatedDebtRedeemedOrRetired
Namespace Prefix: | gain_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Instrument, Covenant, Required Minimum Net Worth Of Mandatory Redeemable Term Preferred Stock, Plus Percent of All Equity and Subordinated Debt Raised + References No definition available. + Details
Name: | gain_DebtInstrumentCovenantRequiredMinimumNetWorthOfMandatoryRedeemableTermPreferredStockPlusPercentOfAllEquityAndSubordinatedDebtRaised
Namespace Prefix: | gain_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Instrument, Variable Rate Floor + References No definition available. + Details
Name: | gain_DebtInstrumentVariableRateFloor
Namespace Prefix: | gain_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investment Company, Senior Security, Indebtedness, Asset Coverage Amount + References No definition available. + Details
Name: | gain_InvestmentCompanySeniorSecurityIndebtednessAssetCoverageAmount
Namespace Prefix: | gain_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
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 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482900/835-30-50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(f)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(a)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-3 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69B -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69B Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69C -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69C Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69E -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69E Reference 8: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69F -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69F Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 11: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1E -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E Reference 19: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1E -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E Reference 20: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1E -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E Reference 21: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 22: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 23: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 24: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 25: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1I -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of total assets less all liabilities and indebtedness not represented by senior security, to senior security representing indebtedness. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name Investment Company Act of 1940 -Section 61 -Paragraph a -Subparagraph (1) -Publisher SEC + Details
Name: | us-gaap_InvestmentCompanySeniorSecurityIndebtednessAssetCoverageRatio
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gain_RevolvingLineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gain_DebtCovenantsAxis=gain_LessThanOrEqualTo50OfCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gain_DebtCovenantsAxis=gain_GreaterThan50ButLessThanOrEqualTo65OfCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gain_DebtCovenantsAxis=gain_GreaterThan65OfCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gain_SecuredOvernightFinancingRateSOFRMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gain_SecuredOvernightFinancingRateSOFRTrancheOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gain_SecuredOvernightFinancingRateSOFRTrancheTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gain_SecuredOvernightFinancingRateSOFRThereafterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gain_SecuredOvernightFinancingRateSOFRThereafterAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gain_LondonInterbankOfferedRateLIBOR1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |