Fair Value of Assets and Liabilities - Valuation Technique (Details) - Level 3	Mar. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($) item
Impaired loans | Appraisal value | Property specific adjustment
Valuation techniques and significant unobservable inputs
Impaired loans	$ 7,139,000	$ 7,325,000
Foreclosed assets | Appraisal value | Property specific adjustment
Valuation techniques and significant unobservable inputs
Foreclosed assets	$ 139,000	$ 63,000
Servicing rights
Valuation techniques and significant unobservable inputs
Servicing Asset, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember	us-gaap:ValuationTechniqueDiscountedCashFlowMember
Servicing rights | Prepayment speed assumptions
Valuation techniques and significant unobservable inputs
Servicing rights	$ 1,952,000	$ 1,987,000
Servicing rights | Prepayment speed assumptions | Minimum
Valuation techniques and significant unobservable inputs
Servicing Asset, Measurement Input | item	175	191
Servicing rights | Prepayment speed assumptions | Maximum
Valuation techniques and significant unobservable inputs
Servicing Asset, Measurement Input | item	298	403
Servicing rights | Prepayment speed assumptions | Weighted average
Valuation techniques and significant unobservable inputs
Servicing Asset, Measurement Input	269	285
Servicing rights | Discount rate
Valuation techniques and significant unobservable inputs
Servicing Asset, Measurement Input	0.090	0.090
Servicing rights | Discount rate | Weighted average
Valuation techniques and significant unobservable inputs
Servicing Asset, Measurement Input	0.090	0.090