XML 58 R45.htm IDEA: XBRL DOCUMENT
v3.25.2

Note 6 - Fair Value - Significant Level 3 Fair Value Measurement Inputs (Details) - Fair Value, Inputs, Level 3 [Member] $ in Thousands | Jun. 30, 2025 USD ($) | Dec. 31, 2024 USD ($)
--- | --- | ---
Investments, fair value |  | $ 620,990 | $ 695,465 |
Investments, measurement input |  | 3.99 |  |
Debt [Member] | Valuation Technique, Discounted Cash Flow [Member] |  |  |  |
Investments, fair value |  | $ 540,426 | $ 628,325 |
Debt [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum [Member] | Hypothetical Market Yield [Member] |  |  |  |
Investments, measurement input |  | 0.10 | 0.11 |
Debt [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum [Member] | Hypothetical Market Yield [Member] |  |  |  |
Investments, measurement input |  | 0.20 | 0.20 |
Debt [Member] | Valuation Technique, Discounted Cash Flow [Member] | Weighted Average [Member] | Hypothetical Market Yield [Member] |  |  |  |
Investments, measurement input | [1] | 0.13 | 0.14 |
Debt [Member] | Multiple Probability Weighted Cash Flow Model [Member] |  |  |  |
Investments, fair value |  | $ 38,745 | $ 10,454 |
Debt [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Minimum [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 0 | 0.10 |
Debt [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Maximum [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 1 | 1 |
Debt [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Weighted Average [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input | [1] | 0.47 | 0.57 |
Warrant [Member] | Black-scholes Valuation Model [Member] |  |  |  |
Investments, fair value |  | $ 15,193 | $ 16,438 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Measurement Input, Price Volatility [Member] |  |  |  |
Investments, measurement input |  | 0.24 | 0.24 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Minimum [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input |  | 0 | 0 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Minimum [Member] | Measurement Input, Discount for Lack of Marketability [Member] |  |  |  |
Investments, measurement input |  | 0 | 0 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Minimum [Member] | Estimated Time to Exit [Member] |  |  |  |
Investments, measurement input |  | 1 | 1 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Maximum [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input |  | 807.91 | 807.91 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Maximum [Member] | Measurement Input, Discount for Lack of Marketability [Member] |  |  |  |
Investments, measurement input |  | 0.20 | 0.20 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Maximum [Member] | Estimated Time to Exit [Member] |  |  |  |
Investments, measurement input |  | 5 | 5 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Weighted Average [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input | [1] | 16.26 | 16.8 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Weighted Average [Member] | Measurement Input, Price Volatility [Member] |  |  |  |
Investments, measurement input | [1] | 0.24 | 0.24 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Weighted Average [Member] | Measurement Input, Discount for Lack of Marketability [Member] |  |  |  |
Investments, measurement input | [1] | 0.20 | 0.15 |
Warrant [Member] | Black-scholes Valuation Model [Member] | Weighted Average [Member] | Estimated Time to Exit [Member] |  |  |  |
Investments, measurement input | [1] | 3 | 3 |
Warrant [Member] | Expected Proceeds [Member] |  |  |  |
Investments, fair value |  | $ 2,712 |  |
Warrant [Member] | Expected Proceeds [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input |  | 32.69 |  |
Warrant [Member] | Expected Proceeds [Member] | Weighted Average [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input | [1] | 32.69 |  |
Other Investments [Member] | Minimum [Member] |  |  |  |
Investments, measurement input |  |  | 0.15 |
Other Investments [Member] | Maximum [Member] |  |  |  |
Investments, measurement input |  |  | 0.25 |
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] |  |  |  |
Investments, fair value |  | $ 8,451 | $ 14,637 |
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Minimum [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 0 | 0.30 |
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Minimum [Member] | Measurement Input, Discount Rate [Member] |  |  |  |
Investments, measurement input |  | 0.25 |  |
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Maximum [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 1 | 1 |
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Maximum [Member] | Measurement Input, Discount Rate [Member] |  |  |  |
Investments, measurement input |  | 0.30 |  |
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Weighted Average [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 0.97 | 0.90 | [1]
Other Investments [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Weighted Average [Member] | Measurement Input, Discount Rate [Member] |  |  |  |
Investments, measurement input | [1] | 0.26 | 0.18 |
Equity Securities [Member] | Multiple Probability Weighted Cash Flow Model [Member] | Weighted Average [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input | [1] | 3.99 |  |
Equity Securities [Member] | Multiple Probability Weighted Scenario Model [Member] |  |  |  |
Investments, fair value |  | $ 2,551 |  |
Equity Securities [Member] | Multiple Probability Weighted Scenario Model [Member] | Probability Weighting [Member] |  |  |  |
Investments, fair value |  | $ 1,281 | $ 3,963 |
Equity Securities [Member] | Multiple Probability Weighted Scenario Model [Member] | Minimum [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 0.20 | 0.10 |
Equity Securities [Member] | Multiple Probability Weighted Scenario Model [Member] | Maximum [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 1 | 1 |
Equity Securities [Member] | Multiple Probability Weighted Scenario Model [Member] | Weighted Average [Member] | Probability Weighting [Member] |  |  |  |
Investments, measurement input |  | 0.33 | 0.33 | [1]
Equity Securities [Member] | Last Equity Financing [Member] |  |  |  |
Investments, fair value |  | $ 11,631 | $ 21,648 |
Equity Securities [Member] | Last Equity Financing [Member] | Minimum [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input |  | 0.06 | 0.06 |
Equity Securities [Member] | Last Equity Financing [Member] | Maximum [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input |  | 215.03 | 215.03 |
Equity Securities [Member] | Last Equity Financing [Member] | Weighted Average [Member] | Measurement Input, Share Price [Member] |  |  |  |
Investments, measurement input | [1] | 54.69 | 30.47 |
[1] | Weighted average is calculated by multiplying (a) the unobservable input for each investment in the investment type by (b) (1) the fair value of the related investment in the investment type divided by (2) the total fair value of the investment type.

X
- Definition Value of input used to measure investment assets. + References No definition available. + Details
Name: | hrzn_InvestmentAssetsMeasurementInput
Namespace Prefix: | hrzn_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 28 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-28 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -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/2009/role/commonPracticeRef -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/2009/role/commonPracticeRef -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 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_DebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_ValuationTechniqueDiscountedCashFlowMember
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: | us-gaap_MeasurementInputTypeAxis=hrzn_HypotheticalMarketYieldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=hrzn_MultipleProbabilityWeightedCashFlowModelMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=hrzn_ProbabilityWeightingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_WarrantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=hrzn_BlackscholesValuationModelMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputSharePriceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountForLackOfMarketabilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=hrzn_EstimatedTimeToExitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=hrzn_ExpectedProceedsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_OtherInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=hrzn_MultipleProbabilityWeightedScenarioModelMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=hrzn_LastEquityFinancingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |