XML 43 R37.htm IDEA: XBRL DOCUMENT
v3.25.3

Portfolio Company Investments - Schedule of Debt Investment on Non-Accrual Status (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Fair Value |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | $ 3,409 | $ 10,270
Fair Value | Suited Connector LLC |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | 1,784 | 5,505
Fair Value | Virtex Enterprises, LP |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | 1,625 | 4,765
Cost |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | 32,382 | 44,379
Cost | Quantum IR Technologies, LLC |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total |  | 11,964
Cost | US GreenFiber, LLC |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | 5,223 | 5,223
Cost | Suited Connector LLC |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | 15,933 | 15,933
Cost | Virtex Enterprises, LP |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Total | $ 11,226 | $ 11,259

X
- Definition Amount of investment in debt security measured at amortized cost (held-to-maturity) on nonaccrual status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 16 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-16 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityNonaccrual
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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/exampleRef -Name Accounting Standards Codification -Section 55 -Paragraph 10 -SubTopic 10 -Topic 825 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482881/825-10-55-10 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-10 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-13 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482881/825-10-55-12 + Details
Name: | us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=fdus_SuitedConnectorLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=fdus_VirtexEnterprisesLpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=fdus_QuantumIRTechnologiesLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=fdus_UsGreenfiberLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |