Concentration of Credit Risk - Summary of Funds Provided Ten Percent or More of Total Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Virtus Vontobel Emerging Markets Opportunities Fund
Concentration Risk [Line Items]
Investment management, administration and shareholder service fees	$ 52,548	$ 48,826	$ 49,085
Virtus Newfleet Multi-Sector Short Term Bond Fund
Concentration Risk [Line Items]
Investment management, administration and shareholder service fees	$ 54,257	$ 44,577	$ 43,579
Sales Revenue, Services, Net | Virtus Vontobel Emerging Markets Opportunities Fund
Concentration Risk [Line Items]
Percent of total revenues	10.00%	12.00%	15.00%
Sales Revenue, Services, Net | Virtus Newfleet Multi-Sector Short Term Bond Fund
Concentration Risk [Line Items]
Percent of total revenues	10.00%	11.00%	14.00%