Fair Value - Assets and liabilities measured at fair value on a nonrecurring basis (Details) - Nonrecurring basis $ in Thousands	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
OREO | Fair Value
Fair Value
Other Real Estate	$ 12,844	$ 11,964	$ 11,297
Non-acquired impaired loans | Fair Value
Fair Value
Other Real Estate	$ 12,264	$ 15,444	$ 1,839
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	us-gaap:MarketApproachValuationTechniqueMember
Long-term Debt, Measurement Input [Extensible List]	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Significant Unobservable Inputs (Level 3) | Impaired loans | Weighted average
Quantitative Information about Level 3 Fair Value Measurements
Discount rate (as a percent)	0.04	0.02	0.03
Significant Unobservable Inputs (Level 3) | OREO
Fair Value
Other Real Estate	$ 12,844	$ 11,964	$ 11,297
Quantitative Information about Level 3 Fair Value Measurements
Long-term Debt, Valuation Technique [Extensible List]	us-gaap:MarketApproachValuationTechniqueMember	us-gaap:MarketApproachValuationTechniqueMember	us-gaap:MarketApproachValuationTechniqueMember
Long-term Debt, Measurement Input [Extensible List]	us-gaap:MeasurementInputCostToSellMember	us-gaap:MeasurementInputCostToSellMember	us-gaap:MeasurementInputCostToSellMember
Significant Unobservable Inputs (Level 3) | OREO | Weighted average
Quantitative Information about Level 3 Fair Value Measurements
Discount rate (as a percent)	0.29	0.31	0.24
Significant Unobservable Inputs (Level 3) | Non-acquired impaired loans
Fair Value
Other Real Estate	$ 12,264	$ 15,444	$ 1,839