Fair Values of Assets and Liabilities Information Regarding Proprietary Fund Products (Details 2) - Proprietary Funds [Member] $ in Thousands	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 227,756	$ 268,268
Number of Proprietary Fund Products with Seed Capital Investment in Excess of One Million Dollars	52	59
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 43,712	$ 43,854