Revenue from contracts with customers - Schedule of Receivables and Deferred Revenue Balances from Contracts with Customers (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	$ 52,324	$ 72,794
Deferred revenue (payables)	5,207	2,132
Investment banking fees
Capitalized Contract Cost [Line Items]
Deferred revenue (payables)	1,440	286
Software license fees
Capitalized Contract Cost [Line Items]
Deferred revenue (payables)	2,395	1,846
IRA fees
Capitalized Contract Cost [Line Items]
Deferred revenue (payables)	1,372	0
Commission
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	9,538	5,011
Mutual fund and insurance income
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	6,125	6,106
Advisory fees
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	4,555	24,166
Bank deposit sweep income
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	3,704	3,876
Investment banking fees
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	23,256	25,414
Other
Capitalized Contract Cost [Line Items]
Contract assets (receivables)	$ 5,146	$ 8,221