| Income Taxes - Schedule of Aggregate Unrealized Appreciation of Company investment Federal Income Tax (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023 | 
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| Income Tax Disclosure [Abstract] | ||
| Aggregate Gross Unrealized Appreciation | $ 127.7 | $ 118.3 | 
| Aggregate Gross Unrealized Depreciation | 129.5 | 115.9 | 
| Net Unrealized Appreciation (Depreciation) over cost for U.S. federal income tax purposes | (1.8) | 2.4 | 
| Aggregate cost of securities for U.S. federal income tax purposes (in billions) | $ 3,600.0 | $ 3,200.0 | 
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- References No definition available. 
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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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