Fair Value - Assets and liabilities measured at fair value on a nonrecurring basis (Details) - Nonrecurring basis $ in Thousands	Jun. 30, 2019 USD ($) item	Dec. 31, 2018 USD ($) item	Jun. 30, 2018 USD ($) item
OREO | Fair Value
Fair Value
Other Real Estate	$ 14,506	$ 11,410	$ 17,222
Non-acquired impaired loans | Fair Value
Fair Value
Other Real Estate	$ 4,946	$ 13,164	$ 5,909
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) | item	0.03	0.03	0.03
Significant Unobservable Inputs (Level 3) | OREO
Fair Value
Other Real Estate	$ 14,506	$ 11,410	$ 17,222
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) | item	0.22	0.23	0.17
Significant Unobservable Inputs (Level 3) | Non-acquired impaired loans
Fair Value
Other Real Estate	$ 4,946	$ 13,164	$ 5,909