Operating lease commitments and contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)
Operating leases
Options to renew	true
Renewal term	5 years
Weighted average remaining lease term	19 years 4 months 24 days	17 years 1 month 6 days
Weighted-average discount rate	3.61%	3.00%
Right-of-use assets	$ 10,600	$ 8,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant and Equipment, Net	Property, Plant and Equipment, Net
Lease liabilities for operating leases	$ 10,960	$ 8,300
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities	Other Liabilities
Number of operating lease added | item	2	0
Number of operating lease not renewed | item	1
Rent expense	$ 1,000	$ 1,000	$ 760
Minimum
Operating leases
Remaining renewal terms	5 years
Discount rate	1.60%	1.60%
Maximum
Operating leases
Remaining renewal terms	30 years
Discount rate	5.25%	3.85%