Revenue from contracts with customers - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 283,906	$ 257,496	$ 586,541	$ 536,207
Interest	34,805	27,320	61,571	52,261
Principal transactions, net	10,074	16,253	28,308	29,743
Other	1,804	5,120	7,307	9,657
Total other sources of revenue	46,683	48,693	97,186	91,661
Total revenue	330,589	306,189	683,727	627,868
Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,957	41	2,958	155
Interest	1,769	808	4,036	2,141
Principal transactions, net	132	1,771	(103)	3,808
Other	64	544	125	1,077
Total other sources of revenue	1,965	3,123	4,058	7,026
Total revenue	3,922	3,164	7,016	7,181
Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	184,641	173,220	369,454	351,128
Interest	21,626	22,403	41,822	42,982
Principal transactions, net	376	1,072	2,112	2,121
Other	2,058	4,550	8,346	8,435
Total other sources of revenue	24,060	28,025	52,280	53,538
Total revenue	208,701	201,245	421,734	404,666
Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26,240	22,196	52,200	46,150
Interest	0	0	0	0
Principal transactions, net	0	0	0	0
Other	(415)	2	(1,447)	7
Total other sources of revenue	(415)	2	(1,447)	7
Total revenue	25,825	22,198	50,753	46,157
Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	71,068	62,039	161,929	138,774
Interest	11,410	4,109	15,713	7,138
Principal transactions, net	9,566	13,410	26,299	23,814
Other	97	24	283	138
Total other sources of revenue	21,073	17,543	42,295	31,090
Total revenue	92,141	79,582	204,224	169,864
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	88,943	80,828	176,923	159,805
Commissions from sales and trading | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3	8	8	14
Commissions from sales and trading | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	44,766	37,666	89,696	76,590
Commissions from sales and trading | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Commissions from sales and trading | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	44,174	43,154	87,219	83,201
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,112	7,716	15,982	15,436
Mutual fund and insurance income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	4	10	8
Mutual fund and insurance income | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,106	7,711	15,970	15,423
Mutual fund and insurance income | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Mutual fund and insurance income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1	1	2	5
Advisory fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	117,197	101,015	232,044	201,559
Advisory fees | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	9	8	20	15
Advisory fees | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	90,947	78,811	179,823	155,394
Advisory fees | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26,241	22,196	52,201	46,150
Advisory fees | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	16,828	9,033	35,476	19,061
Investment banking - capital markets | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	(1)	0	(1)	0
Investment banking - capital markets | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,807	1,688	5,828	3,475
Investment banking - capital markets | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Investment banking - capital markets | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	14,022	7,345	29,649	15,586
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	12,291	10,945	44,180	38,882
Investment banking - advisory | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Investment banking - advisory | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	21	0
Investment banking - advisory | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Investment banking - advisory | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	12,291	10,945	44,159	38,882
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	34,846	44,060	71,531	92,969
Bank deposit sweep income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	(1)	0	(1)	0
Bank deposit sweep income | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	34,847	44,060	71,532	92,969
Bank deposit sweep income | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Bank deposit sweep income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,689	3,899	10,405	8,495
Other | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,942	21	2,922	118
Other | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,168	3,284	6,584	7,277
Other | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	(1)	0	(1)	0
Other | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 580	$ 594	$ 900	$ 1,100