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Investments - Textual (Details) - USD ($) | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
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Debt and Equity Securities, FV-NI [Line Items] |  |  |
Investments from the Deferred Compensation Plans | $ 9,000,000.0 | $ 6,900,000 | $ 3,800,000
Company sponsored equity method investments | $ 94,023,248 | $ 84,530,289 |
DMHF |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Equity method investment | 84.00% | 85.00% | 85.00%
Company sponsored equity method investments | $ 22,900,000 | $ 17,700,000 |
Large Cap Concentrated Fund |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Equity method investment | 43.00% | 47.00% | 48.00%
Diamond Hill International Fund |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Equity method investment | 40.00% | 49.00% |
Securities held in Consolidated Funds |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Trading Investments | $ 35,583,162 | $ 0 |
Parent | Securities held in Consolidated Funds |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Trading Investments | 35,400,000 |  |
Redeemable Noncontrolling Interest | Securities held in Consolidated Funds |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Trading Investments | $ 200,000 |  |

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