Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 1,140,120	$ 1,075,985	$ 2,292,766	$ 2,159,856
Not subject to contracts with customers:
Dividend and interest income, net of broker-dealer related interest expense	16,689	20,475	34,154	37,308
Investment gains (losses)	13,505	(7,825)	44,564	(28,363)
Other revenues	690	272	1,246	713
Total revenue not from contract with customer	30,884	12,922	79,964	9,658
Net revenues	1,171,004	1,088,907	2,372,730	2,169,514
Base fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	860,302	805,319	1,709,484	1,623,185
Performance-based fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	46,644	38,659	112,676	75,905
All-in-management fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	89,887	86,926	180,695	175,370
12b-1 fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	14,772	15,248	29,538	31,500
Other distribution fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	96,260	96,193	193,504	190,517
Shareholder servicing fees
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	23,752	21,278	47,940	37,920
JV related revenues
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	6,628	9,013	12,989	18,347
Other
Disaggregation of Revenue [Line Items]
Revenue subject to contracts with customers	$ 1,875	$ 3,349	$ 5,940	$ 7,112