Revenues from contracts with customers (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 260,188	$ 350,169
Interest	9,517	8,666
Principal transactions, net	2,364	10,865
Other	(6,041)	3,582
Total other sources of revenue	5,840	23,113
Total revenue	$ 266,028	373,282
Commission From Equity Securities Transactions
Disaggregation of Revenue [Line Items]
Revenue settlement period	2 days
Commissions From Corporate Bond Transactions
Disaggregation of Revenue [Line Items]
Revenue settlement period	1 day
Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 90,002	104,195
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenue settlement period	90 days
Revenues from contracts with customers	$ 8,319	9,276
Advisory fees
Disaggregation of Revenue [Line Items]
Revenue settlement period	90 days
Revenues from contracts with customers	$ 115,766	104,496
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenue settlement period	90 days
Revenues from contracts with customers	$ 16,530	88,579
Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 21,940	35,922
Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenue settlement period	30 days
Revenues from contracts with customers	$ 4,354	4,008
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,277	3,693
Private Client
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	150,736	153,488
Interest	8,147	6,476
Principal transactions, net	(1,933)	630
Other	(6,103)	3,429
Total other sources of revenue	111	10,535
Total revenue	150,847	164,023
Private Client | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	43,355	48,398
Private Client | Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,322	9,198
Private Client | Advisory fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	88,527	80,254
Private Client | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,306	8,510
Private Client | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	35	0
Private Client | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,354	4,008
Private Client | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,837	3,120
Asset Management
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	27,113	24,227
Interest	0	0
Principal transactions, net	0	0
Other	4	3
Total other sources of revenue	4	3
Total revenue	27,117	24,230
Asset Management | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Asset Management | Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Asset Management | Advisory fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	27,113	24,227
Asset Management | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Asset Management | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Asset Management | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Asset Management | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	82,205	172,355
Interest	1,293	2,152
Principal transactions, net	1,516	8,954
Other	37	138
Total other sources of revenue	2,846	11,244
Total revenue	85,051	183,599
Capital markets | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	46,636	55,800
Capital markets | Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	5	2
Capital markets | Advisory fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	117	3
Capital markets | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	13,224	80,069
Capital markets | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	21,905	35,922
Capital markets | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0
Capital markets | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	318	559
Corporate/Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	134	99
Interest	77	38
Principal transactions, net	2,781	1,281
Other	21	12
Total other sources of revenue	2,879	1,331
Total revenue	3,013	1,430
Corporate/Other | Commissions from sales and trading
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	11	(3)
Corporate/Other | Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(8)	76
Corporate/Other | Advisory fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	9	12
Corporate/Other | Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Corporate/Other | Investment banking - advisory
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Corporate/Other | Bank deposit sweep income
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0
Corporate/Other | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 122	$ 14