Allowance for credit losses - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses reserve	$ 18.2
Commercial
Financing Receivable, Modifications [Line Items]
Outstanding commitments to lend additional funds to debtors owing receivables whose terms have been modified	$ 95.0	$ 75.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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