Revenue from Contracts with Customers - Disaggregation of Revenue by Performance Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total Revenue	$ 1,609,574	$ 1,445,814	$ 1,300,447
Asset Management
Disaggregation of Revenue [Line Items]
Total Revenue	1,115,783	1,011,631	915,984
Administrative Services
Disaggregation of Revenue [Line Items]
Total Revenue	343,332	294,557	306,639
Distribution
Disaggregation of Revenue [Line Items]
Total Revenue	126,350	112,356	49,600
Other
Disaggregation of Revenue [Line Items]
Total Revenue	$ 24,109	$ 27,270	$ 28,224