Allowance for credit losses - loans held-in-portfolio - Additional Information (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Commercial Loan Portfolio
Financing Receivable, Modified [Line Items]
Outstanding commitments to lend additional funds to debtors	$ 85.6	$ 159.1

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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