Acquisitions - Additional Information (Details) - USD ($)
3 Months Ended 12 Months Ended
Jul. 01, 2019
Sep. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Sep. 21, 2018
Acquisitions            
Contingent consideration liability $ 98,800,000   $ 118,700,000 $ 716,000 $ 1,195,000  
Goodwill     $ 404,750,000 284,108,000 284,108,000  
Percentage of projected annual growth rate for non managed money revenue 3.00%          
Percentage of market price risk 4.00%          
Percentage of revenue volatility 20.00%          
Discount rate 7.00%   5.00%      
Change in fair value of contingent consideration obligations     $ 19,886,000 (37,000) (294,000)  
Percentage of projected annual growth rate for non managed money revenue during earn out period     4.00%      
Acquisition-related costs     $ 2,300,000   400,000  
Minimum            
Acquisitions            
Undiscounted earn out payments $ 119,000,000          
Estimated undiscounted earn out payments     133,000,000      
Maximum            
Acquisitions            
Undiscounted earn out payments $ 150,000,000          
Estimated undiscounted earn out payments     150,000,000      
USAA AMCO            
Acquisitions            
Percentage of outstanding common stock acquired 100.00%          
Total consideration $ 950,100,000          
Payments to acquire business 851,300,000          
Payments to acquire business, restricted cash 71,900,000          
Contingent consideration liability 98,800,000          
Maximum aggregate contingent payment 150,000,000          
Maximum annual contingent payment $ 37,500,000          
Period of time over which contingent payments will be made 4 years          
Contingent consideration threshold percentage 80.00%          
Annual revenue percentage requirement to achieve the maximum contingent payment 100.00%          
Goodwill $ 120,643,000   $ 120,600,000      
Post-closing adjustment period     1 year      
Change in fair value of contingent consideration obligations     $ (19,900,000)      
Acquisition-related costs     8,700,000 0 0  
Harvest            
Acquisitions            
Equity interest to be acquired (as a percent)           100.00%
CEMP            
Acquisitions            
Change in fair value of contingent consideration obligations     $ 14,000 37,000    
Earnout period     4 years      
Base and earn-out payments made   $ 6,000,000 $ 6,000,000 $ 4,400,000 $ 2,700,000