Loans (Collateral-dependent Loans by Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 3,091,998		$ 3,081,973
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	21,121
Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,018
Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	669
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,687
Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	26,495
Commercial and Industrial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	638,773	$ 534,692	589,758
Commercial and Industrial Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4,943
Commercial and Industrial Loans | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,014
Commercial and Industrial Loans | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	669
Commercial and Industrial Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	154
Commercial and Industrial Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,780
Commercial Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,467,397	1,500,247	1,495,862
Commercial Real Estate Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11,877
Commercial Real Estate Loans | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Commercial Real Estate Loans | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Commercial Real Estate Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,530
Commercial Real Estate Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	13,407
Agricultural Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	376,186	384,654	384,526
Agricultural Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,064
Agricultural Loans | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Agricultural Loans | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Agricultural Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Agricultural Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,064
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	55,664	57,257
Leases | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Leases | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Leases | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Leases | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Leases | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Home Equity Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	219,348	225,790	225,755
Home Equity Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	416
Home Equity Loans | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Home Equity Loans | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Home Equity Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Home Equity Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	416
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	66,717	69,264	81,217
Consumer Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4
Consumer Loans | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	4
Consumer Loans | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Consumer Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3
Consumer Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11
Credit Cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	11,637	11,953
Credit Cards | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Credit Cards | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Credit Cards | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Credit Cards | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Credit Cards | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	256,276	$ 305,002	$ 304,855
Residential Mortgage Loans | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	817
Residential Mortgage Loans | Equipment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Residential Mortgage Loans | Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Residential Mortgage Loans | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	0
Residential Mortgage Loans | Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 817