Business and Organization	6 Months Ended
Jun. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Organization	Business and Organization Diamond Hill Investment Group, Inc., an Ohio corporation (“DHIL” and, collectively with its subsidiaries, the “Company”), derives its consolidated revenues and net income from investment advisory and fund administration services provided by its wholly-owned subsidiary, Diamond Hill Capital Management, Inc., an Ohio corporation (“DHCM”). DHCM is a registered investment adviser. DHCM is the investment adviser and administrator for the Diamond Hill Funds, a series of open-end mutual funds (each a “Diamond Hill Fund”, and collectively, the “Diamond Hill Funds”), and the Diamond Hill Securitized Credit Fund, a closed-end registered investment company (“DHSC”, and collectively with the Diamond Hill Funds, the “Proprietary Funds”). DHCM also provides investment advisory and related services to the Diamond Hill Micro Cap Fund, LP (“DHMF”), a private fund, as well as separately managed accounts (“SMAs”), collective investment trusts (“CITs”), other pooled vehicles including sub-advised funds, and model delivery programs.

Business and Organization

6 Months Ended

Jun. 30, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Diamond Hill Investment Group, Inc., an Ohio corporation (“DHIL” and, collectively with its subsidiaries, the “Company”), derives its consolidated revenues and net income from investment advisory and fund administration services provided by its wholly-owned subsidiary, Diamond Hill Capital Management, Inc., an Ohio corporation (“DHCM”).

DHCM is a registered investment adviser. DHCM is the investment adviser and administrator for the Diamond Hill Funds, a series of open-end mutual funds (each a “Diamond Hill Fund”, and collectively, the “Diamond Hill Funds”), and the Diamond Hill Securitized Credit Fund, a closed-end registered investment company (“DHSC”, and collectively with the Diamond Hill Funds, the “Proprietary Funds”). DHCM also provides investment advisory and related services to the Diamond Hill Micro Cap Fund, LP (“DHMF”), a private fund, as well as separately managed accounts (“SMAs”), collective investment trusts (“CITs”), other pooled vehicles including sub-advised funds, and model delivery programs.