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Investment Portfolio (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Summary of market value of investments
Total Investment Portfolio	$ 16,503,731	$ 8,208,489
Diamond Hill Small Cap Fund [Member]
Summary of market value of investments
Total Investment Portfolio	215,550	189,042
Diamond Hill Small-Mid Cap Fund [Member]
Summary of market value of investments
Total Investment Portfolio	239,316	203,571
Diamond Hill Large Cap Fund [Member]
Summary of market value of investments
Total Investment Portfolio	246,744	213,110
Diamond Hill Select Fund [Member]
Summary of market value of investments
Total Investment Portfolio	242,252	214,833
Diamond Hill Long-Short Fund [Member]
Summary of market value of investments
Total Investment Portfolio	1,036,045	212,720
Diamond Hill Research Opportunities Fund [Member]
Summary of market value of investments
Total Investment Portfolio	10,658,665
Diamond Hill Strategic Income Fund [Member]
Summary of market value of investments
Total Investment Portfolio	214,598	197,284
Diamond Hill Investment Partners, L.P. [Member]
Summary of market value of investments
Total Investment Portfolio	7,336	156,122
Diamond Hill Investment Partners II, L.P. [Member]
Summary of market value of investments
Total Investment Portfolio		131,203
Diamond Hill Research Partners, L.P. [Member]
Summary of market value of investments
Total Investment Portfolio		5,770,874
Diamond Hill Research Partners - International, L.P. [Member]
Summary of market value of investments
Total Investment Portfolio	1,384,976	919,730
Diamond Hill Valuation-Based Index L.P. [Member]
Summary of market value of investments
Total Investment Portfolio	$ 2,258,249

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- Definition

Sum of the carrying amounts as of the balance sheet date of all investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(h))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph h

-Article 7

+ Details

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