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Summary of Significant Accounting Policies (Impact of ASC 326 in Balance Sheet as January 1, 2020) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	$ 3,091,998		$ 3,081,973
Allowance for Credit Losses	(46,859)	$ (31,931)	(16,278)	$ (15,823)	$ (15,694)
Allowance for Credit Losses on Unfunded Loan Commitments		(173)
Commercial and Industrial Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	638,773	534,692	589,758
Allowance for Credit Losses	(6,445)		(4,799)
Commercial Real Estate Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	1,467,397	1,500,247	1,495,862
Allowance for Credit Losses	(29,878)		(4,692)	(5,291)	(4,591)
Agricultural Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	376,186	384,654	384,526
Allowance for Credit Losses	(6,756)		(5,315)	(5,776)	(4,894)
Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	55,664	57,257
Allowance for Credit Losses	(200)		0
Home Equity Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	219,348	225,790	225,755
Allowance for Credit Losses	(996)		(200)	(229)	(330)
Consumer Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	66,717	69,264	81,217
Allowance for Credit Losses	(490)		(434)	(420)	(298)
Credit Cards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	11,637	11,953
Allowance for Credit Losses	(150)		0
Residential Mortgage Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans	256,276	305,002	304,855
Allowance for Credit Losses	$ (1,944)		(333)	$ (472)	$ (343)
Adjusted Balance
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			3,081,973
Allowance for Credit Losses			(16,278)
Allowance for Credit Losses on Unfunded Loan Commitments			0
Adjusted Balance \| Commercial and Industrial Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			532,501
Adjusted Balance \| Commercial Real Estate Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			1,495,862
Adjusted Balance \| Agricultural Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			384,526
Adjusted Balance \| Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			57,257
Adjusted Balance \| Home Equity Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			225,755
Adjusted Balance \| Consumer Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			69,264
Adjusted Balance \| Credit Cards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			11,953
Adjusted Balance \| Residential Mortgage Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			304,855
Impact of ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans			0
Allowance for Credit Losses		(15,653)
Allowance for Credit Losses on Unfunded Loan Commitments		(173)
Impact of ASC 326 Adoption \| Commercial and Industrial Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		2,191	(57,257)
Impact of ASC 326 Adoption \| Commercial Real Estate Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		4,385
Impact of ASC 326 Adoption \| Agricultural Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		128
Impact of ASC 326 Adoption \| Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		0	57,257
Impact of ASC 326 Adoption \| Home Equity Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		35
Impact of ASC 326 Adoption \| Consumer Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		0	(11,953)
Impact of ASC 326 Adoption \| Credit Cards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		0	$ 11,953
Impact of ASC 326 Adoption \| Residential Mortgage Loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loans		$ 147