Revenue from contracts with customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	$ 302,635	$ 278,711
Interest	26,766	24,941
Principal transactions, net	18,234	13,490
Other	5,503	4,537
Total other sources of revenue	50,503	42,968
Total revenue	353,138	321,679
Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	1,001	114
Interest	2,267	1,333
Principal transactions, net	(235)	2,037
Other	61	533
Total other sources of revenue	2,093	3,903
Total revenue	3,094	4,017
Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	184,813	177,908
Interest	20,196	20,579
Principal transactions, net	1,736	1,049
Other	6,288	3,885
Total other sources of revenue	28,220	25,513
Total revenue	213,033	203,421
Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	25,960	23,954
Interest	0	0
Principal transactions, net	0	0
Other	(1,032)	5
Total other sources of revenue	(1,032)	5
Total revenue	24,928	23,959
Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	90,861	76,735
Interest	4,303	3,029
Principal transactions, net	16,733	10,404
Other	186	114
Total other sources of revenue	21,222	13,547
Total revenue	112,083	90,282
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	87,980	78,977
Commissions from sales and trading | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	5	6
Commissions from sales and trading | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	44,930	38,924
Commissions from sales and trading | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Commissions from sales and trading | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	43,045	40,047
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	7,870	7,720
Mutual fund and insurance income | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	5	4
Mutual fund and insurance income | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	7,864	7,712
Mutual fund and insurance income | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Mutual fund and insurance income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	1	4
Advisory fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	114,847	100,544
Advisory fees | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	11	7
Advisory fees | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	88,876	76,583
Advisory fees | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	25,960	23,954
Advisory fees | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	18,648	10,028
Investment banking - capital markets | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Investment banking - capital markets | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	3,021	1,787
Investment banking - capital markets | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Investment banking - capital markets | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	15,627	8,241
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	31,889	27,937
Investment banking - advisory | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Investment banking - advisory | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	21	0
Investment banking - advisory | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Investment banking - advisory | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	31,868	27,937
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	36,685	48,909
Bank deposit sweep income | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Bank deposit sweep income | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	36,685	48,909
Bank deposit sweep income | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Bank deposit sweep income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	4,716	4,596
Other | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	980	97
Other | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	3,416	3,993
Other | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	0	0
Other | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers:	$ 320	$ 506