Revenue from contracts with customers - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	$ 46,187	$ 39,861
Contract with Customer, Liability	930	1,118
Investment banking fees
Contracts with Customers Assets and Liabilities [Line Items]
Contract with Customer, Liability	28	1,118
Software license fees
Contracts with Customers Assets and Liabilities [Line Items]
Contract with Customer, Liability	902	0
Commission
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	4,408	4,554
Mutual fund and insurance income
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	5,838	5,365
Advisory fees
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	11,271	5,746
Bank deposit sweep income
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	4,748	5,223
Investment banking fees
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	14,798	12,847
Other
Contracts with Customers Assets and Liabilities [Line Items]
Total receivables	$ 5,124	$ 6,126