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Significant Accounting Policies - Summary of Investments Values Based Upon Level 1and Level 2 (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Level 1 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of Investment	$ 61,162,721dhil_ValueOfInvestment / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	$ 62,595,546dhil_ValueOfInvestment / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Level 2 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of Investment	$ 15,121,155dhil_ValueOfInvestment / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member	$ 14,652,589dhil_ValueOfInvestment / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member

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- Definition

Value of investment.

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