XML 39 R28.htm IDEA: XBRL DOCUMENT
v3.19.2

Significant Accounting Policies - Narrative (Detail) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) Segment | Jun. 30, 2018 USD ($) | Dec. 31, 2018 USD ($)
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Number of business segment | Segment |  |  | 1 |  |
Accounts receivable, related parties | $ 9,600,000 |  | $ 9,600,000 |  | $ 9,400,000
Client performance period |  |  | 5 years |  |
Revenue | 33,545,016 | $ 35,927,715 | $ 66,124,389 | $ 73,709,717 |
Advance commissions amortization period |  |  | 12 months |  |
Variable Rate Fees |  |  |  |  |
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Revenue | $ 0 | $ 0 | $ 0 | $ 0 |

X
- Definition Advance commissions amortization period. + References No definition available. + Details
Name: | dhil_AdvanceCommissionsAmortizationPeriod
Namespace Prefix: | dhil_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition [Line Items] for Business Organization And Significant Accounting Policies [Table] + References No definition available. + Details
Name: | dhil_BusinessOrganizationAndSignificantAccountingPoliciesLineItems
Namespace Prefix: | dhil_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rolling Client Investment Performance Period + References No definition available. + Details
Name: | dhil_RollingClientInvestmentPerformancePeriod
Namespace Prefix: | dhil_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition For an unclassified balance sheet, amount of receivables arising from transactions with related parties. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(3)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(3)(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(k)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_AccountsReceivableRelatedParties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References No definition available. + Details
Name: | us-gaap_NumberOfOperatingSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
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_VariableRateFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |