Fair Value - Assets and liabilities measured at fair value on a nonrecurring basis (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Fair Value
OREO	$ 3,687	$ 11,914
Impaired loans	88,383	95,188
Nonrecurring basis | Fair Value
Fair Value
OREO	3,687	11,914
Bank property held for sale	15,076	36,006
Impaired loans	18,225	17,609
Nonrecurring basis | Significant Unobservable Inputs (Level 3)
Fair Value
OREO	3,687	11,914
Bank property held for sale	15,076	36,006
Impaired loans	$ 18,225	$ 17,609
Nonrecurring basis | Significant Unobservable Inputs (Level 3) | Impaired loans
Quantitative Information about Level 3 Fair Value Measurements
Long-term Debt, Valuation Technique [Extensible List]	us-gaap:MarketApproachValuationTechniqueMember	us-gaap:MarketApproachValuationTechniqueMember
Long-term Debt, Measurement Input [Extensible List]	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Nonrecurring basis | Significant Unobservable Inputs (Level 3) | Impaired loans | Weighted average
Quantitative Information about Level 3 Fair Value Measurements
Discount rate (as a percent)	5	5
Nonrecurring basis | Significant Unobservable Inputs (Level 3) | OREO
Quantitative Information about Level 3 Fair Value Measurements
Long-term Debt, Valuation Technique [Extensible List]	us-gaap:MarketApproachValuationTechniqueMember	us-gaap:MarketApproachValuationTechniqueMember
Long-term Debt, Measurement Input [Extensible List]	us-gaap:MeasurementInputCostToSellMember	us-gaap:MeasurementInputCostToSellMember
Nonrecurring basis | Significant Unobservable Inputs (Level 3) | OREO | Weighted average
Quantitative Information about Level 3 Fair Value Measurements
Discount rate (as a percent)	26	14