Revenues from contracts with customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 257,496	$ 238,633	$ 536,207	$ 498,819
Interest	27,320	11,789	52,261	21,306
Principal transactions, net	16,253	1,258	29,743	3,622
Other	5,120	(14,458)	9,657	(20,497)
Total other sources of revenue	48,693	(1,411)	91,661	4,431
Total revenue	306,189	237,222	627,868	503,250
Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	41	111	155	244
Interest	808	28	2,141	104
Principal transactions, net	1,771	(3,073)	3,808	(292)
Other	544	96	1,077	119
Total other sources of revenue	3,123	(2,949)	7,026	(69)
Total revenue	3,164	(2,838)	7,181	175
Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	173,220	151,012	351,128	301,747
Interest	22,403	10,369	42,982	18,517
Principal transactions, net	1,072	(2,233)	2,121	(4,166)
Other	4,550	(14,677)	8,435	(20,780)
Total other sources of revenue	28,025	(6,541)	53,538	(6,429)
Total revenue	201,245	144,471	404,666	295,318
Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	22,196	24,311	46,150	51,424
Interest	0	0	0	0
Principal transactions, net	0	0	0	0
Other	2	4	7	8
Total other sources of revenue	2	4	7	8
Total revenue	22,198	24,315	46,157	51,432
Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	62,039	63,199	138,774	145,404
Interest	4,109	1,392	7,138	2,685
Principal transactions, net	13,410	6,564	23,814	8,080
Other	24	119	138	156
Total other sources of revenue	17,543	8,075	31,090	10,921
Total revenue	79,582	71,274	169,864	156,325
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	80,828	86,539	159,805	176,541
Commissions from sales and trading | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8	6	14	17
Commissions from sales and trading | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	37,666	38,108	76,590	81,463
Commissions from sales and trading | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Commissions from sales and trading | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	43,154	48,425	83,201	95,061
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,716	7,839	15,436	16,158
Mutual fund and insurance income | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4	30	8	22
Mutual fund and insurance income | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,711	7,808	15,423	16,130
Mutual fund and insurance income | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Mutual fund and insurance income | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1	1	5	6
Advisory fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	101,015	107,405	201,559	223,171
Advisory fees | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8	9	15	17
Advisory fees | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	78,811	83,085	155,394	171,613
Advisory fees | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	22,196	24,311	46,150	51,424
Advisory fees | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	117
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	9,033	8,369	19,061	24,899
Investment banking - capital markets | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - capital markets | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,688	2,359	3,475	5,665
Investment banking - capital markets | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - capital markets | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,345	6,010	15,586	19,234
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10,945	8,284	38,882	30,224
Investment banking - advisory | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - advisory | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	35
Investment banking - advisory | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Investment banking - advisory | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	10,945	8,284	38,882	30,189
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	44,060	14,845	92,969	19,199
Bank deposit sweep income | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Bank deposit sweep income | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	44,060	14,845	92,969	19,199
Bank deposit sweep income | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Bank deposit sweep income | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,899	5,352	8,495	8,627
Other | Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	21	66	118	188
Other | Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,284	4,807	7,277	7,642
Other | Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	0	0
Other | Capital Markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 594	$ 479	$ 1,100	$ 797