Taxable/Distributable Income and Dividend Distributions - Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
Sep. 30, 2024 |
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| Investments, Owned, Federal Income Tax Note [Line Items] | |||||
| Undistributed ordinary income, net | $ 696.0 | ||||
| Valuation allowance | $ 6.2 | $ 6.2 | |||
| Deferred tax assets | 6.5 | 6.5 | |||
| Investment income, operating, tax expense (benefit), realized and unrealized gains (loss) | 0.1 | $ 0.2 | 0.6 | $ 0.6 | |
| Unrealized gain (loss), investment and derivative, operating, tax expense (benefit) | $ 0.3 | 0.4 | |||
| Current income tax | $ 0.1 | ||||
| Cost of investments | 3,153.0 | ||||
| Unrealized appreciation | 674.5 | ||||
| Unrealized depreciation | 812.5 | ||||
| Unrealized appreciation (depreciation) | 138.0 | ||||
| Short-Term Capital Loss Carryforward | |||||
| Investments, Owned, Federal Income Tax Note [Line Items] | |||||
| Undistributed ordinary income, net | 73.0 | ||||
| Long-Term Capital Loss Carryforward | |||||
| Investments, Owned, Federal Income Tax Note [Line Items] | |||||
| Undistributed ordinary income, net | $ 623.0 | ||||
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- Definition Investment Income, Operating, Tax Expense (Benefit), Realized And Unrealized Gains (Loss) No definition available.
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of accumulated undistributed deficit from capital loss carryforward of investment company. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- 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. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount of cost of investment for federal income tax purpose. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of cumulative increase in investment from unrealized gain when value exceeds cost for federal income tax purpose. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of cumulative decrease in investment from unrealized loss when cost for federal income tax purpose exceeds value. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of cumulative increase (decrease) in investment from unrealized gain (loss) when value exceeds (is less than) cost for federal income tax purpose. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of tax expense (benefit) from unrealized gain (loss) from investment and derivative, classified as operating. Investment includes, but is not limited to, debt and equity securities, security sold short, real estate, and commodity. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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