Investments - Summary of Financial Information for Company's Equity Method Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statements of operations:
Total revenues	$ 2,025,401	$ 1,795,302	$ 2,015,364
Total expenses	1,992,830	1,717,115	2,178,215
Net income (loss) available to common stockholders	38,775	58,867	153,488
Statements of financial condition:
Cash and cash equivalents	655,641	484,989
Fixed assets, net	178,300	183,478
Other assets	496,655	463,014
Assets	3,175,937	3,074,971
Payables to related parties	17,456	10,550
Total partners’ capital	898,156	733,208	663,315	$ 811,297
Total liabilities, redeemable partnership interest, and equity	3,175,937	3,074,971
Equity Method Investment Nonconsolidated Investee
Statements of operations:
Total revenues	111,242	125,405	108,458
Total expenses	84,216	88,050	82,581
Net income (loss) available to common stockholders	27,026	37,355	$ 25,877
Statements of financial condition:
Cash and cash equivalents	79,440	82,725
Fixed assets, net	1,900	1,848
Other assets	51,336	54,744
Assets	132,676	139,317
Payables to related parties	0	0
Other liabilities	81,898	78,740
Total partners’ capital	50,779	60,577
Total liabilities, redeemable partnership interest, and equity	$ 132,677	$ 139,317