XML 58 R43.htm IDEA: XBRL DOCUMENT v3.10.0.1

Operating Leases - Textual (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) ft² Location	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Leases [Abstract]
Lessee leasing agreements, operating leases, area under lease (in sqft) | ft²	37,829
Number of office space locations | Location	1
Operating lease expense excluding rent | $	$ 0.4	$ 0.4	$ 0.4

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

Operating Lease Expense Excluding Rent

+ References

No definition available.

+ Details

Name:	dhil_OperatingLeaseExpenseExcludingRent
Namespace Prefix:	dhil_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

The number of units (items of property) under operating lease arrangements.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseNumberOfUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant