Loans (Schedule of Carrying Amount of Loans with Deterioration of Credit Quality) (Details) - USD ($) $ in Thousands	Jun. 30, 2018		Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 2,331,331	[1]	$ 2,154,502	[2]
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	519,749	[1]	488,058	[2]
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	988,993	[1]	929,040	[2]
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	356,517	[1]	337,801	[2]
Residential Mortgage Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	223,886	[1]	179,199	[2]
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	7,776		9,117
Carrying Amount, Net of Allowance	7,739		9,106
Receivables Acquired with Deteriorated Credit Quality | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	783		988
Receivables Acquired with Deteriorated Credit Quality | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	5,174		6,452
Receivables Acquired with Deteriorated Credit Quality | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	951		789
Receivables Acquired with Deteriorated Credit Quality | Residential Mortgage Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, net of deferred income	$ 868		$ 888

[1] Total recorded investment in loans includes $9,486 in accrued interest.

[2] Total recorded investment in loans includes $9,483 in accrued interest.