Loans (Components of Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 3,225,232			$ 3,081,973
Less: Unearned Income	(4,105)			(4,882)
Allowance for credit losses	(46,768)	$ (42,431)	$ (31,931)	(16,278)	$ (15,869)	$ (16,239)	$ (15,823)
Loans, Net	3,174,359			3,060,813
Commercial and Industrial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	781,547		534,692	589,758
Allowance for credit losses	(7,700)	(8,787)		(4,799)
Commercial Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,453,280		1,500,247	1,495,862
Allowance for credit losses	(28,382)	(22,369)		(4,692)	(4,300)	(5,841)	(5,291)
Agricultural Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	376,215		384,654	384,526
Allowance for credit losses	(6,715)	(7,030)		(5,315)	(5,352)	(5,725)	(5,776)
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	57,475		57,257
Allowance for credit losses	(206)	(202)		0
Home Equity Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	218,640		225,790	225,755
Allowance for credit losses	(995)	(1,062)		(200)	(194)	(258)	(229)
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	64,919		69,264	81,217
Allowance for credit losses	(492)	(496)		(434)	(418)	(422)	(420)
Credit Cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	10,717		11,953
Allowance for credit losses	(137)	(125)		0
Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	262,439		$ 305,002	304,855
Allowance for credit losses	(2,141)	$ (2,360)		(333)	$ (362)	$ (349)	$ (472)
Commercial | Commercial and Industrial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	781,547			532,501
Commercial | Commercial Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,453,280			1,495,862
Commercial | Agricultural Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	376,215			384,526
Commercial | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	57,475			57,257
Retail | Home Equity Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	218,640			225,755
Retail | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	64,919			69,264
Retail | Credit Cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	10,717			11,953
Retail | Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 262,439			$ 304,855