Fair Value Measurements - Classes of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financial Assets
Cash and Cash Equivalents	$ 504,441	$ 383,180
Investments—Consolidated Investment Companies	82,441	70,543
Investments—Affiliates and Other	54,160	106,952
Other	9,570	7,804
Total Financial Assets	650,612	568,479
Financial Liabilities
Total Financial Liabilities	3,172	7,961
Level 1
Financial Assets
Cash and Cash Equivalents	504,441	383,180
Investments—Consolidated Investment Companies	12,090	11,402
Investments—Affiliates and Other	51,847	104,341
Other	9,570	6,160
Total Financial Assets	577,948	505,083
Financial Liabilities
Total Financial Liabilities	0	0
Level 2
Financial Assets
Cash and Cash Equivalents	0	0
Investments—Consolidated Investment Companies	70,351	59,141
Investments—Affiliates and Other	2,290	2,588
Other	0	1,644
Total Financial Assets	72,641	63,373
Financial Liabilities
Total Financial Liabilities	2,819	335
Level 3
Financial Assets
Cash and Cash Equivalents	0	0
Investments—Consolidated Investment Companies	0	0
Investments—Affiliates and Other	23	23
Other	0	0
Total Financial Assets	23	23
Financial Liabilities
Total Financial Liabilities	$ 353	$ 7,626