Revenue from contracts with customers - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 316,640	$ 275,191	$ 903,181	$ 812,084
Interest	38,034	26,430	99,605	78,691
Principal transactions, net	14,364	16,892	42,672	46,635
Other	4,314	(5,846)	11,621	3,126
Total other sources of revenue	56,712	37,476	153,898	128,452
Total revenue	373,352	312,667	1,057,079	940,536
Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,003	42	3,961	198
Interest	1,856	936	5,892	3,077
Principal transactions, net	353	2,484	250	6,292
Other	61	545	186	1,622
Total other sources of revenue	2,270	3,965	6,328	10,991
Total revenue	3,273	4,007	10,289	11,189
Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	189,338	174,814	558,792	525,942
Interest	24,331	21,248	66,153	64,230
Principal transactions, net	977	(612)	3,089	1,509
Other	4,141	(2,196)	12,487	6,239
Total other sources of revenue	29,449	18,440	81,729	71,978
Total revenue	218,787	193,254	640,521	597,920
Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	27,432	25,188	79,632	72,023
Interest	0	0	0	0
Principal transactions, net	0	0	0	0
Other	(170)	(4,358)	(1,617)	(5,036)
Total other sources of revenue	(170)	(4,358)	(1,617)	(5,036)
Total revenue	27,262	20,830	78,015	66,987
Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	98,867	75,147	260,796	213,921
Interest	11,847	4,246	27,560	11,384
Principal transactions, net	13,034	15,020	39,333	38,834
Other	282	163	565	301
Total other sources of revenue	25,163	19,429	67,458	50,519
Total revenue	124,030	94,576	328,254	264,440
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	94,842	75,719	271,765	235,524
Commissions from sales and trading | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	4	14	18
Commissions from sales and trading | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	46,641	36,176	136,337	112,766
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	48,195	39,539	135,414	122,740
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,237	8,214	24,219	23,650
Mutual fund and insurance income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	4	15	12
Mutual fund and insurance income | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,231	8,209	24,201	23,632
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	3	6
Advisory fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	121,631	107,969	353,675	310,214
Advisory fees | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	11	7	31	23
Advisory fees | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	94,188	82,774	274,011	238,168
Advisory fees | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	27,432	25,188	79,633	72,023
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	19,387	19,410	54,863	38,471
Investment banking - capital markets | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	(1)	0
Investment banking - capital markets | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,410	2,115	8,238	5,590
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	16,977	17,295	46,626	32,881
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	32,798	18,001	76,978	56,883
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	32,798	18,001	76,957	56,883
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	34,875	42,304	106,406	135,273
Bank deposit sweep income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	(1)	0
Bank deposit sweep income | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	34,875	42,304	106,407	135,273
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	4,870	3,574	15,275	12,069
Other | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	981	27	3,903	145
Other | Private Client | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,993	3,236	9,577	10,513
Other | Asset Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	(1)	0
Other | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 896	$ 311	$ 1,796	$ 1,411