Segment Information - Segment's Contribution with Respect to Net Revenue, Operating Expenses, Operating Income (Loss) and Total Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net Revenue	$ 726,744	$ 717,429	$ 2,061,182	$ 2,200,673
Operating Expenses	568,602	562,470	1,617,474	1,745,163
Operating Income (Loss)	158,142	154,959	443,708	455,510
Total Assets	6,207,925		6,207,925		$ 7,147,181
Operating Segments [Member] | Financial Advisory Segment [Member]
Segment Reporting Information [Line Items]
Net Revenue	456,521	384,976	1,254,621	1,155,328
Operating Expenses	341,578	304,482	956,410	931,612
Operating Income (Loss)	114,943	80,494	298,211	223,716
Total Assets	1,175,237		1,175,237		1,239,964
Operating Segments [Member] | Asset Management Segment [Member]
Segment Reporting Information [Line Items]
Net Revenue	298,797	338,747	926,449	1,051,492
Operating Expenses	233,614	246,094	707,676	747,511
Operating Income (Loss)	65,183	92,653	218,773	303,981
Total Assets	912,481		912,481		1,128,549
Corporate [Member]
Segment Reporting Information [Line Items]
Net Revenue	(28,574)	(6,294)	(119,888)	(6,147)
Operating Expenses	(6,590)	11,894	(46,612)	66,040
Operating Income (Loss)	(21,984)	$ (18,188)	(73,276)	$ (72,187)
Total Assets	$ 4,120,207		$ 4,120,207		$ 4,778,668