Revenue from contracts with customers - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 399,372	$ 324,149
Interest	37,531	36,369
Principal transactions, net	10,787	8,975
Other	(2,595)	(1,668)
Total other sources of revenue	45,723	43,676
Total revenue	445,095	367,825
Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,261	1,342
Interest	1,250	1,430
Principal transactions, net	(221)	(233)
Other	3	39
Total other sources of revenue	1,032	1,236
Total revenue	2,293	2,578
Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	236,604	223,089
Interest	20,863	21,485
Principal transactions, net	(897)	(587)
Other	(2,890)	(2,001)
Total other sources of revenue	17,076	18,897
Total revenue	253,680	241,986
Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	161,507	99,718
Interest	15,418	13,454
Principal transactions, net	11,905	9,795
Other	292	294
Total other sources of revenue	27,615	23,543
Total revenue	189,122	123,261
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	119,522	102,727
Commissions from sales and trading | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	14	12
Commissions from sales and trading | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	51,567	48,767
Commissions from sales and trading | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67,941	53,948
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,819	8,151
Mutual fund and insurance income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	6
Mutual fund and insurance income | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,811	8,144
Mutual fund and insurance income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1	1
Advisory fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	141,718	128,803
Advisory fees | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	24	11
Advisory fees | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	141,694	128,792
Advisory fees | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	34,456	21,661
Investment banking - capital markets | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Investment banking - capital markets | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,935	2,962
Investment banking - capital markets | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	30,521	18,699
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	63,264	25,962
Investment banking - advisory | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Investment banking - advisory | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	268	0
Investment banking - advisory | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	62,996	25,962
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26,118	30,075
Bank deposit sweep income | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Bank deposit sweep income | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26,118	30,075
Bank deposit sweep income | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,475	6,770
Other | Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,216	1,313
Other | Wealth Management | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,211	4,349
Other | Capital Markets | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 48	$ 1,108