Leases - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) branch_office	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term	21 years
Weighted average discount rate	3.27%
Operating right-of-use lease assets	$ 17,514	$ 19,669
Lease liabilities	17,868	19,855
Total operating lease expense	$ 2,900
Total operating lease expense		$ 2,600	$ 2,300
Minimum
Lessee, Lease, Description [Line Items]
Option extension period	5 years
Maximum
Lessee, Lease, Description [Line Items]
Option extension period	10 years
Land and Building
Lessee, Lease, Description [Line Items]
Number of branch locations | branch_office	9
Land
Lessee, Lease, Description [Line Items]
Number of branch locations | branch_office	8