Concentration of Credit Risk - Summary of Funds Provided Ten Percent or More of Total Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Virtus Emerging Markets Opportunities Fund [Member]
Concentration Risk [Line Items]
Investment management, administration and transfer agent fees	$ 49,085	$ 62,329	$ 50,435
Virtus Multi-Sector Short Term Bond Fund [Member]
Concentration Risk [Line Items]
Investment management, administration and transfer agent fees	$ 43,579	$ 49,174	$ 55,401
Sales Revenue, Services, Net [Member] | Virtus Emerging Markets Opportunities Fund [Member]
Concentration Risk [Line Items]
Percent of total revenues	15.00%	16.00%	11.00%
Sales Revenue, Services, Net [Member] | Virtus Multi-Sector Short Term Bond Fund [Member]
Concentration Risk [Line Items]
Percent of total revenues	14.00%	13.00%	12.00%