Loans (Schedule of Carrying Amount of Loans with Deterioration of Credit Quality) (Details) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 2,098,726	[1]	$ 2,001,415	[2]
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	476,167	[1]	458,538	[2]
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	900,937	[1]	858,030	[2]
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	331,482	[1]	306,946	[2]
Consumer Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	63,816	[1]	60,099	[2]
Residential Mortgage Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	179,931	[1]	183,770	[2]
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	9,099		11,048
Carrying Amount, Net of Allowance	9,088		10,943
Receivables Acquired with Deteriorated Credit Quality | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	945		1,656
Receivables Acquired with Deteriorated Credit Quality | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	6,492		7,688
Receivables Acquired with Deteriorated Credit Quality | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	768		706
Receivables Acquired with Deteriorated Credit Quality | Consumer Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	0		53
Receivables Acquired with Deteriorated Credit Quality | Residential Mortgage Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 894		$ 945

[1] Total recorded investment in loans includes $9,013 in accrued interest.

[2] Total recorded investment in loans includes $8,011 in accrued interest.