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Securities, at Fair Value - Impairment and Other Net Gain/(Loss) on Securities and Other Portfolio Investments (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2025 | Mar. 31, 2024
Gain (Loss) on Securities [Line Items] |  |
Total Impairment and other net gain/(loss) on securities and other portfolio investments | $ 21,179 | $ (4,776)
Securities |  |
Gain (Loss) on Securities [Line Items] |  |
Net unrealized gain/(loss) on other portfolio investments | 20,201 | (4,112)
Net realized gain/(loss) on other portfolio investments | 234 | 0
Impairment of securities | 0 | 0
Total Impairment and other net gain/(loss) on securities and other portfolio investments | 20,435 | (4,112)
Other Portfolio Investments |  |
Gain (Loss) on Securities [Line Items] |  |
Net unrealized gain/(loss) on other portfolio investments | 753 | (664)
Net realized gain/(loss) on other portfolio investments | $ (9) | $ 0

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