Segment information - Schedule of Reported Revenue and Pre-Tax Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue
Revenue	$ 373,352	$ 312,667	$ 1,057,079	$ 940,536
Pre-Tax Income (Loss)
Pre-Tax Income (Loss)	35,370	21,587	88,690	28,938
Corporate/Other
Revenue
Revenue	3,273	4,007	10,289	11,189
Pre-Tax Income (Loss)
Pre-Tax Income (Loss)	$ (30,501)	$ (33,359)	$ (88,720)	$ (84,744)
Private Client
Pre-Tax Income (Loss)
Asset management fees (as a percent)	90.00%	90.00%	90.00%	90.00%
Private Client | Operating Segments
Revenue
Revenue	$ 218,787	$ 193,254	$ 640,521	$ 597,920
Pre-Tax Income (Loss)
Pre-Tax Income (Loss)	$ 62,894	$ 65,249	$ 186,582	$ 140,499
Asset Management
Pre-Tax Income (Loss)
Asset management fees (as a percent)	10.00%	10.00%	10.00%	10.00%
Asset Management | Operating Segments
Revenue
Revenue	$ 27,262	$ 20,830	$ 78,015	$ 66,987
Pre-Tax Income (Loss)
Pre-Tax Income (Loss)	9,121	4,951	25,449	17,965
Capital markets | Operating Segments
Revenue
Revenue	124,030	94,576	328,254	264,440
Pre-Tax Income (Loss)
Pre-Tax Income (Loss)	$ (6,144)	$ (15,254)	$ (34,621)	$ (44,782)