Employee benefit plans - Salaries and Employee Benefits Expense - ESOP (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Peoples Security Bank and Trust ESOP
Peoples Security Bank and Trust ESOP
Contribution to ESOP	$ 0.0	$ 0.2	$ 0.3

This item represents the amount of cash contributions during the period made by the entity to the Employee Stock Ownership Plan (ESOP).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480489/718-40-50-1

Name:	us-gaap_EmployeeStockOwnershipPlanESOPCashContributionsToESOP
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration