Revenue from contracts with customers - Schedule of Receivables and Deferred Revenue Balances from Contracts with Customers (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	$ 50,121	$ 72,794
Deferred revenue (payables)	2,442	2,132
Investment Banking fees
Capitalized Contract Cost [Line Items]
Deferred revenue (payables)	1,153	286
Software license fees
Capitalized Contract Cost [Line Items]
Deferred revenue (payables)	1,289	1,846
Commission
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	7,618	5,011
Mutual fund and insurance income
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	6,199	6,106
Advisory fees
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	4,873	24,166
Bank deposit sweep income
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	4,192	3,876
Investment Banking fees
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	21,544	25,414
Other
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	$ 5,695	$ 8,221