Restrictions on cash and due from banks and certain securities (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Restricted Cash and Investments [Abstract]
Average reserve required with federal reserve bank	$ 2,600.0	$ 2,700.0
Restricted cash and cash equivalent	$ 68.0	$ 64.0

- Definition

Amount of cash and cash equivalent restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposit with financial institution, and account with general characteristic of demand deposit. Cash equivalent includes, but is not limited to, short-term, highly liquid investment that is both readily convertible to known amount of cash and so near maturity that it presents insignificant risk of change in value because of change in interest rate.

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