Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Total revenue	$ 139,951	$ 154,187	$ 441,571	$ 424,203
Open-end funds
Disaggregation of Revenue [Line Items]
Total revenue	80,500	88,026	256,246	237,082
Institutional accounts
Disaggregation of Revenue [Line Items]
Total revenue	32,500	38,039	103,612	106,407
Closed-end funds
Disaggregation of Revenue [Line Items]
Total revenue	26,951	28,122	81,713	80,714
North America
Disaggregation of Revenue [Line Items]
Total revenue	122,944	134,243	387,572	368,685
Japan
Disaggregation of Revenue [Line Items]
Total revenue	8,824	9,960	27,610	28,021
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenue	4,986	6,593	16,344	17,869
Asia Pacific excluding Japan
Disaggregation of Revenue [Line Items]
Total revenue	$ 3,197	$ 3,391	$ 10,045	$ 9,628