Revenue from contracts with customers - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 370,215	$ 316,640	$ 1,007,769	$ 903,181
Interest	38,859	38,034	113,245	99,605
Principal transactions, net	14,902	14,364	38,409	42,672
Other	462	4,314	6,018	11,621
Total other sources of revenue	54,223	56,712	157,672	153,898
Total revenue	424,438	373,352	1,165,441	1,057,079
Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,419	1,003	4,196	3,961
Interest	1,693	1,856	4,945	5,892
Principal transactions, net	(546)	353	(271)	250
Other	1	61	51	186
Total other sources of revenue	1,148	2,270	4,725	6,328
Total revenue	2,567	3,273	8,921	10,289
Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	235,896	216,770	674,416	638,424
Interest	22,381	24,331	65,808	66,153
Principal transactions, net	1,254	977	2,640	3,089
Other	195	3,971	5,269	10,870
Total other sources of revenue	23,830	29,279	73,717	80,112
Total revenue	259,726	246,049	748,133	718,536
Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	132,900	98,867	329,157	260,796
Interest	14,785	11,847	42,492	27,560
Principal transactions, net	14,194	13,034	36,040	39,333
Other	266	282	698	565
Total other sources of revenue	29,245	25,163	79,230	67,458
Total revenue	162,145	124,030	408,387	328,254
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	112,326	94,842	317,486	271,765
Commissions from sales and trading | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8	6	32	14
Commissions from sales and trading | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	53,511	46,641	149,481	136,337
Commissions from sales and trading | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	58,807	48,195	167,973	135,414
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,358	8,237	24,101	24,219
Mutual fund and insurance income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	5	19	15
Mutual fund and insurance income | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,350	8,231	24,079	24,201
Mutual fund and insurance income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1	1	3	3
Advisory fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	134,404	121,631	388,835	353,675
Advisory fees | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	11	36	31
Advisory fees | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	134,397	121,620	388,799	353,644
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	55,185	19,387	97,891	54,863
Investment banking - capital markets | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	(1)
Investment banking - capital markets | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,042	2,410	8,762	8,238
Investment banking - capital markets | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	52,143	16,977	89,129	46,626
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	22,303	32,798	70,753	76,978
Investment banking - advisory | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
Investment banking - advisory | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	438	0	438	21
Investment banking - advisory | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	21,865	32,798	70,315	76,957
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	28,349	34,875	87,078	106,406
Bank deposit sweep income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	(1)
Bank deposit sweep income | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	28,349	34,875	87,078	106,407
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	9,290	4,870	21,625	15,275
Other | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,397	981	4,109	3,903
Other | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7,809	2,993	15,779	9,576
Other | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 84	$ 896	$ 1,737	$ 1,796