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Concentration Risk - Schedule of Revenue Concentration (Details) - Product Concentration Risk
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Equity Assets    
Concentration Risk [Line Items]    
Concentration risk 38.00% 40.00%
Money Market Assets    
Concentration Risk [Line Items]    
Concentration risk 43.00% 38.00%
Fixed-Income Assets    
Concentration Risk [Line Items]    
Concentration risk 13.00% 14.00%