Loans, Allowance for Credit Losses - Loans, and Credit Quality - Collateral dependent loans by portfolio segment (Details) $ in Thousands	Jun. 30, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 9,155
Without an Allowance	3,282
With an Allowance	5,873
Allowance Allocation	1,379
Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	4,632
Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	4,523
Retail & other
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Without an Allowance	0
With an Allowance	0
Allowance Allocation	0
Retail & other | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Retail & other | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Commercial portfolio segment | Commercial & industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	3,688
Without an Allowance	0
With an Allowance	3,688
Allowance Allocation	1,231
Commercial portfolio segment | Commercial & industrial | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Commercial portfolio segment | Commercial & industrial | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	3,688
Commercial portfolio segment | PPP loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Without an Allowance	0
With an Allowance	0
Allowance Allocation	0
Commercial portfolio segment | PPP loans | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Commercial portfolio segment | PPP loans | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Commercial portfolio segment | Owner-occupied commercial real estate (“CRE”)
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	2,524
Without an Allowance	339
With an Allowance	2,185
Allowance Allocation	148
Commercial portfolio segment | Owner-occupied commercial real estate (“CRE”) | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	2,524
Commercial portfolio segment | Owner-occupied commercial real estate (“CRE”) | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Commercial portfolio segment | Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,435
Without an Allowance	1,435
With an Allowance	0
Allowance Allocation	0
Commercial portfolio segment | Agricultural | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	600
Commercial portfolio segment | Agricultural | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	835
Commercial real estate portfolio segment | CRE investment
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	975
Without an Allowance	975
With an Allowance	0
Allowance Allocation	0
Commercial real estate portfolio segment | CRE investment | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	975
Commercial real estate portfolio segment | CRE investment | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Commercial real estate portfolio segment | Construction & land development
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	533
Without an Allowance	533
With an Allowance	0
Allowance Allocation	0
Commercial real estate portfolio segment | Construction & land development | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	533
Commercial real estate portfolio segment | Construction & land development | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Residential | Residential construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Without an Allowance	0
With an Allowance	0
Allowance Allocation	0
Residential | Residential construction | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Residential | Residential construction | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Residential | Residential first mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Without an Allowance	0
With an Allowance	0
Allowance Allocation	0
Residential | Residential first mortgage | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Residential | Residential first mortgage | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Residential | Residential junior mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Without an Allowance	0
With an Allowance	0
Allowance Allocation	0
Residential | Residential junior mortgage | Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	0
Residential | Residential junior mortgage | Other Business Assets
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 0