Revenue from contracts with customers - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Disaggregation of Revenue [Line Items]
Contract assets (receivables)	$ 72,800	$ 46,200
Deferred revenue (payables)	2,132	930
Capitalized contract costs	$ 2,100	$ 2,000
Commission From Equity Securities Transactions
Disaggregation of Revenue [Line Items]
Revenue settlement period (in days)	1 day
Mutual fund and insurance income
Disaggregation of Revenue [Line Items]
Revenue settlement period (in days)	90 days
Advisory fees
Disaggregation of Revenue [Line Items]
Revenue settlement period (in days)	90 days
Investment banking - capital markets
Disaggregation of Revenue [Line Items]
Revenue settlement period (in days)	90 days
Bank Deposit Sweep Income
Disaggregation of Revenue [Line Items]
Revenue settlement period (in days)	30 days