XML 38 R27.htm IDEA: XBRL DOCUMENT
v3.20.1

Significant Accounting Policies - Assets under Management (AUM) Subject to Incentive Fees and Incentive Fees (Detail) | 3 Months Ended
--- | ---
Mar. 31, 2020 USD ($)
Quarter Ending December 31, 2019 |
Principal Transaction Revenue [Line Items] |
AUM subject to variable rate fees | $ 48,120,435
Unearned variable rate fees | 357,648
Quarter Ending September 30, 2021 |
Principal Transaction Revenue [Line Items] |
AUM subject to variable rate fees | 227,221,875
Unearned variable rate fees | 7,465,020
Total |
Principal Transaction Revenue [Line Items] |
AUM subject to variable rate fees | 275,342,310
Unearned variable rate fees | $ 7,822,668

X
- Definition Assets under management (AUM) subject to variable rate fees and variable rate fees. + References No definition available. + Details
Name: | dhil_AssetsUnderManagementVariableRateFees
Namespace Prefix: | dhil_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Potential Variable Fees Based Upon Current Investment Results + References No definition available. + Details
Name: | dhil_PotentialVariableFeesBasedUponCurrentInvestmentResults
Namespace Prefix: | dhil_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_PrincipleTransactionRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PrincipleTransactionRevenueDescriptionOfReportingCategoryAxis=dhil_AssetUnderManagementContractualPeriodEndDateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PrincipleTransactionRevenueDescriptionOfReportingCategoryAxis=dhil_AssetUnderManagementContractualPeriodEndDate4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PrincipleTransactionRevenueDescriptionOfReportingCategoryAxis=dhil_AssetUnderManagementContractualPeriodEndTotalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |