XML 42 R23.htm IDEA: XBRL DOCUMENT v2.4.0.8

Business and Organization - Additional Information (Detail)	Sep. 30, 2013 Subsidiary
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of operating subsidiaries	3

X

- Definition

Number of operating subsidiaries.

+ References

No definition available.

+ Details

Name:	dhil_NumberOfOperatingSubsidiaries
Namespace Prefix:	dhil_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration