Segment information - Reported Revenue and Profit Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue
Total	$ 312,667	$ 294,111	$ 940,536	$ 797,361
Pre-Tax Income (Loss)
Total pre-tax income (loss)	21,587	7,238	28,938	15,282
Corporate/Other
Revenue
Total	4,007	(320)	11,189	(145)
Pre-Tax Income (Loss)
Total pre-tax income (loss)	$ (33,359)	$ (33,458)	$ (84,744)	$ (89,185)
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
Total	$ 193,254	$ 178,614	$ 597,920	$ 473,932
Pre-Tax Income (Loss)
Total pre-tax income (loss)	$ 65,249	$ 29,973	$ 140,499	$ 92,919
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
Total	$ 20,830	$ 24,870	$ 66,987	$ 76,302
Pre-Tax Income (Loss)
Total pre-tax income (loss)	4,951	8,322	17,965	25,916
Capital markets | Operating Segments
Revenue
Total	94,576	90,947	264,440	247,272
Pre-Tax Income (Loss)
Total pre-tax income (loss)	$ (15,254)	$ 2,401	$ (44,782)	$ (14,368)