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Investments - Selected Statement of Operations Information for SLP III and SLP IV (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Investment Company, Nonconsolidated Subsidiary [Line Items] |  |  |  |
Total investment income | $ 95,327 | $ 94,349 | $ 280,471 | $ 281,794
Interest and other financing expenses | 37,661 | 31,425 | 101,790 | 93,921
Total expenses | 60,791 | 55,315 | 171,469 | 165,575
Net investment income | 35,506 | 40,047 | 111,734 | 119,391
Net realized gains (losses) on investments |  |  | (43,524) | 7,904
Net change in unrealized (depreciation) appreciation of investments |  |  | 23,368 | (18,340)
SLP III |  |  |  |
Investment Company, Nonconsolidated Subsidiary [Line Items] |  |  |  |
Interest income | 17,860 | 16,848 | 51,245 | 48,083
Other income | 49 | 295 | 134 | 452
Total investment income | 17,909 | 17,143 | 51,379 | 48,535
Interest and other financing expenses | 8,888 | 9,061 | 26,599 | 26,336
Other expenses | 229 | 317 | 737 | 853
Total expenses | 9,117 | 9,378 | 27,336 | 27,189
Net investment income | 8,792 | 7,765 | 24,043 | 21,346
Net realized gains (losses) on investments | 74 | (545) | (5,833) | (2,400)
Net change in unrealized (depreciation) appreciation of investments | (1,493) | 11,856 | 5,005 | 27,810
Net increase in members' capital | 7,373 | 19,076 | 23,215 | 46,756
SLP IV |  |  |  |
Investment Company, Nonconsolidated Subsidiary [Line Items] |  |  |  |
Interest income | 12,906 | 12,476 | 37,025 | 35,669
Other income | 10 | 100 | 77 | 258
Total investment income | 12,916 | 12,576 | 37,102 | 35,927
Interest and other financing expenses | 6,694 | 6,447 | 19,436 | 18,455
Other expenses | 202 | 221 | 651 | 653
Total expenses | 6,896 | 6,668 | 20,087 | 19,108
Net investment income | 6,020 | 5,908 | 17,015 | 16,819
Net realized gains (losses) on investments | 133 | (97) | (4,741) | (1,751)
Net change in unrealized (depreciation) appreciation of investments | (2,076) | 10,361 | 1,468 | 19,942
Net increase in members' capital | $ 4,077 | $ 16,172 | $ 13,742 | $ 35,010

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