Revenue Recognition - Receivables from Contracts with Customers (Details) - USD ($) $ in Thousands |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Disaggregation of revenue | ||
| Receivables from contracts with customers | $ 41,734 | $ 41,133 |
| Non-customer receivables | 2,450 | 2,987 |
| Accounts Receivable, Net, Total | 44,184 | 44,120 |
| Mutual funds | ||
| Disaggregation of revenue | ||
| Receivables from contracts with customers | 21,328 | 21,025 |
| ETF's | ||
| Disaggregation of revenue | ||
| Receivables from contracts with customers | 870 | 909 |
| Separate accounts and other vehicles | ||
| Disaggregation of revenue | ||
| Receivables from contracts with customers | $ 19,536 | $ 19,199 |