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Investments and Other Marketable Securities - Investments Available For Sale (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Available for sale debt securities, Cost | $ 154,211 | $ 127,681
Available for sale debt securities, Fair Value | 143,126 | 118,752
Available for sale and equity securities, Cost | 192,794 | 163,409
Available for sale and equity securities, Gross Unrealized Gains | 1,947 | 952
Available for sale and equity securities, Gross Unrealized (Losses) | (11,085) | (8,948)
Available for sale and equity securities, Fair Value | 183,656 | 155,413
Available for sale debt securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Available for sale debt securities, Cost | 154,211 | 127,681
Available for sale debt securities, Gross Unrealized Gains | 0 | 0
Available for sale debt securities, Gross Unrealized (Losses) | (11,085) | (8,929)
Available for sale debt securities, Fair Value | 143,126 | 118,752
SEI-sponsored investment products |  |
Debt Securities, Available-for-sale [Line Items] |  |
Equity securities, FV-NI, Cost | 33,029 | 30,427
Equity securities, FV-NI, Gross Unrealized Gains | 1,615 | 818
Equity securities, FV-NI, Gross Unrealized (Losses) | 0 | (19)
Equity securities, FV-NI, Fair Value | 34,644 | 31,226
Equities and other investment products |  |
Debt Securities, Available-for-sale [Line Items] |  |
Equity securities, FV-NI, Cost | 5,554 | 5,301
Equity securities, FV-NI, Gross Unrealized Gains | 332 | 134
Equity securities, FV-NI, Gross Unrealized (Losses) | 0 | 0
Equity securities, FV-NI, Fair Value | $ 5,886 | $ 5,435

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