XML 36 R25.htm IDEA: XBRL DOCUMENT
v3.19.2

Significant Accounting Policies - Revenues From Contracts with Customers (Details) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | $ 33,545,016 | $ 35,927,715 | $ 66,124,389 | $ 73,709,717
Investment advisory |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 31,510,672 | 33,526,273 | 62,023,389 | 68,157,563
Mutual fund administration, net |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 2,034,344 | 2,401,442 | 4,101,000 | 5,552,154
Proprietary funds |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 26,369,713 | 28,696,350 | 52,016,246 | 59,152,260
Proprietary funds | Investment advisory |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 24,335,369 | 26,294,908 | 47,915,246 | 53,600,106
Proprietary funds | Mutual fund administration, net |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 2,034,344 | 2,401,442 | 4,101,000 | 5,552,154
Sub-advised funds and institutional accounts |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 7,175,303 | 7,231,365 | 14,108,143 | 14,557,457
Sub-advised funds and institutional accounts | Investment advisory |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | 7,175,303 | 7,231,365 | 14,108,143 | 14,557,457
Sub-advised funds and institutional accounts | Mutual fund administration, net |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue | $ 0 |  | $ 0 | $ 0

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_DisaggregationOfRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_ProductOrServiceAxis=dhil_InvestmentAdvisoryServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=dhil_MutualFundAdministrativeServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=dhil_ProprietaryFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=dhil_SubadvisedFundsAndInstitutionalAccountsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |