Revenue from contracts with customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 1,047,158	$ 1,318,869
Interest	60,713	36,482	$ 33,477
Principal transactions, net	21,031	23,984	27,874
Other	(17,961)	14,700
Total other sources of revenue	63,783	75,166
Total revenue	1,110,941	1,394,035	1,198,667
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	339,175	364,860
Mutual fund income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	31,207	36,747
Advisory fees
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	425,615	451,197
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	42,833	240,867
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	84,696	195,003
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	104,558	15,557
Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	19,074	14,638
Private Client
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	647,342	618,437
Interest	51,866	29,290
Principal transactions, net	(4,013)	3,195
Other	(19,515)	14,138
Total other sources of revenue	28,338	46,623
Total revenue	675,680	665,060	642,083
Private Client | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	159,441	181,073
Private Client | Mutual fund income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	31,173	36,651
Private Client | Advisory fees
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	326,240	346,559
Private Client | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	9,352	24,965
Private Client | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	127	250
Private Client | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	104,558	15,557
Private Client | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	16,451	13,382
Asset Management
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	99,224	104,584
Interest	0	0
Principal transactions, net	0	0
Other	18	14
Total other sources of revenue	18	14
Total revenue	99,242	104,598	130,274
Asset Management | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Asset Management | Mutual fund income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Asset Management | Advisory fees
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	99,224	104,584
Asset Management | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Asset Management | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Asset Management | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Asset Management | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Capital markets
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	299,982	595,642
Interest	7,453	6,990
Principal transactions, net	29,610	22,598
Other	776	474
Total other sources of revenue	37,839	30,062
Total revenue	337,821	625,704	$ 426,752
Capital markets | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	179,694	183,778
Capital markets | Mutual fund income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	8	8
Capital markets | Advisory fees
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	117	3
Capital markets | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	33,481	215,902
Capital markets | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	84,569	194,753
Capital markets | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Capital markets | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	2,113	1,198
Corporate/Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	610	206
Interest	1,394	202
Principal transactions, net	(4,566)	(1,809)
Other	760	74
Total other sources of revenue	(2,412)	(1,533)
Total revenue	(1,802)	(1,327)
Corporate/Other | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	40	9
Corporate/Other | Mutual fund income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	26	88
Corporate/Other | Advisory fees
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	34	51
Corporate/Other | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Corporate/Other | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Corporate/Other | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	0	0
Corporate/Other | Other
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers	$ 510	$ 58