Concentration of Credit Risk - Summary of Funds Provided Ten Percent or More of Total Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Virtus Emerging Markets Opportunities Fund [Member]
Concentration Risk [Line Items]
Investment management, administration and transfer agent fees	$ 62,329	$ 50,435	$ 53,202
Virtus Multi-Sector Short Term Bond Fund [Member]
Concentration Risk [Line Items]
Investment management, administration and transfer agent fees	49,174	55,401	52,568
Virtus Equity Trend Fund (formerly Virtus Premium AlphaSector Fund) [Member]
Concentration Risk [Line Items]
Investment management, administration and transfer agent fees	$ 30,398	$ 61,566	$ 41,921
Sales Revenue, Services, Net [Member] | Virtus Emerging Markets Opportunities Fund [Member]
Concentration Risk [Line Items]
Percent of total revenues	16.00%	11.00%	14.00%
Sales Revenue, Services, Net [Member] | Virtus Multi-Sector Short Term Bond Fund [Member]
Concentration Risk [Line Items]
Percent of total revenues	13.00%	12.00%	14.00%
Sales Revenue, Services, Net [Member] | Virtus Equity Trend Fund (formerly Virtus Premium AlphaSector Fund) [Member]
Concentration Risk [Line Items]
Percent of total revenues	8.00%	14.00%	11.00%