Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues	$ 227,029	$ 219,271	$ 673,455	$ 630,681
Investment management fees
Disaggregation of Revenue [Line Items]
Revenues	193,843	184,869	573,855	529,326
Open-end funds
Disaggregation of Revenue [Line Items]
Revenues	79,428	80,294	237,991	229,721
Closed-end funds
Disaggregation of Revenue [Line Items]
Revenues	14,942	14,673	43,741	44,025
Retail separate accounts
Disaggregation of Revenue [Line Items]
Revenues	52,068	44,441	153,265	127,323
Institutional accounts
Disaggregation of Revenue [Line Items]
Revenues	$ 47,405	$ 45,461	$ 138,858	$ 128,257