Loans (Schedule of Risk Category of Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	$ 1,457,768	[1]	$ 1,390,802	[2]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	8,361		14,753		11,174
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	380,851	[1]	351,903	[2]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	354		1,981		1,840
Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	584,426	[1]	583,604	[2]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	6,385		10,871		9,037
Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	219,640	[1]	195,171	[2]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	0		0
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	651		3,121
Pass | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	351,250		324,685
Pass | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	545,804		539,533
Pass | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	214,974		192,609
Pass | Total
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	1,112,028		1,056,827
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	1,697		661
Special Mention | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	18,387		15,485
Special Mention | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	23,421		20,168
Special Mention | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	4,211		2,357
Special Mention | Total
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	46,019		38,010
Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	4,391		9,070
Substandard | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	11,214		11,733
Substandard | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	15,201		23,903
Substandard | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	455		205
Substandard | Total
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	26,870		35,841
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	0		0
Doubtful | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	0		0
Doubtful | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	0		0
Doubtful | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	0		0
Doubtful | Total
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	0		0
Total by Risk Category
Financing Receivable, Recorded Investment [Line Items]
Loans Acquired with Deteriorated Credit Quality (Included in the Total Above)	6,739		12,852
Total by Risk Category | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	380,851		351,903
Total by Risk Category | Commercial Real Estate Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	584,426		583,604
Total by Risk Category | Agricultural Loans
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	219,640		195,171
Total by Risk Category | Total
Financing Receivable, Recorded Investment [Line Items]
Total Ending Loans Balance	$ 1,184,917		$ 1,130,678

[1] Total recorded investment in loans includes $5,778 in accrued interest.

[2] Total recorded investment in loans includes $5,590 in accrued interest.