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v3.22.2

Income Taxes - Narrative (Detail) | 6 Months Ended
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Jun. 30, 2022 | Jun. 30, 2021
Income Tax Disclosure [Abstract] |  |
Unconsolidated effective income tax rate | 25.20% | 26.40%

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- Definition Effective Income Tax Rate Reconciliation, Not Including Non-Controlling Interest, Percent + References No definition available. + Details
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Namespace Prefix: | dhil_
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Balance Type: | na
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- References No definition available. + Details
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