XML 47 R40.htm IDEA: XBRL DOCUMENT
v3.20.1

Operating Lease - Narrative (Detail) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2020 USD ($) ft² location
Leases [Abstract] |
Area of operating lease | ft² | 37,829
Number of office space locations | location | 1
Operating lease, right-of-use asset | $ 2.4
Operating lease, liability | $ 3.0

X
- Definition Lessee Leasing Agreements, Operating Leases, Area under Lease + References No definition available. + Details
Name: | dhil_LesseeLeasingAgreementsOperatingLeasesAreaunderLease
Namespace Prefix: | dhil_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessee Leasing Agreements, Operating Leases, locations + References No definition available. + Details
Name: | dhil_LesseeLeasingAgreementsOperatingLeaseslocations
Namespace Prefix: | dhil_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LeasesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
Name: | us-gaap_OperatingLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
Name: | us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant