Business Segment Information - Summary of Net Revenues Derived From Investment Management, Research and Related Services (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Revenues:
Total revenues	$ 1,214,731	$ 1,098,124
Less: Broker-dealer related Interest expense	13,005	17,517
Net revenues	1,201,726	1,080,607
Reportable Segment
Revenues:
Total revenues	1,214,731	1,098,124
Less: Broker-dealer related Interest expense	13,005	17,517
Net revenues	1,201,726	1,080,607
Institutions | Reportable Segment
Revenues:
Total revenues	214,593	172,005
Retail | Reportable Segment
Revenues:
Total revenues	613,866	599,972
Private Wealth Management | Reportable Segment
Revenues:
Total revenues	313,761	298,797
Other | Reportable Segment
Revenues:
Total revenues	$ 72,511	$ 27,350