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Borrowings - SBA-guaranteed Debentures, Narrative (Details) $ in Thousands | 12 Months Ended |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
SBA-guaranteed debentures outstanding | $ 300,000 | $ 300,000 | $ 300,000 | $ 300,000 | $ 225,000 | $ 165,000 | $ 150,000 | $ 121,700 | $ 117,700 | $ 37,500
Upfront fees percentage | 0.03435 |  |  |  |  |  |  |  |  |
Commitment fee percentage | 0.0100 |  |  |  |  |  |  |  |  |
Issuance discount percentage | 0.02435 |  |  |  |  |  |  |  |  |
SBIC I |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory capital | $ 75,000 | 75,000 |  |  |  |  |  |  |  |
SBA-guaranteed debentures outstanding | 150,000 | 150,000 |  |  |  |  |  |  |  |
SBIC II |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory capital | 75,000 | 75,000 |  |  |  |  |  |  |  |
SBA-guaranteed debentures outstanding | $ 150,000 | $ 150,000 |  |  |  |  |  |  |  |
SBA-guaranteed debentures |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Term of debt | 10 years |  |  |  |  |  |  |  |  |
Interest rate margin | 0.41% |  |  |  |  |  |  |  |  |

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